 in that it uses an oxidation and reduction reaction to produce energy. However, in a fuel cell, reactants are intermittently supplied from an outside source and thus, reaction products are consecutively removed from a fuel cell system. In a chemical cell, however, the battery reaction is performed within a closed system.
Currently, commercialization of the fuel cell has begun to take off because the reaction product of the fuel cell is pure water and thus is very environmentally friendly. Accordingly, research for using fuel cells as an energy source for vehicles is of great interest in the automotive industry.
A fuel cell is often made up of a stack assembly in which a plurality of unit cells are consecutively disposed one on top of/next to the other, which is referred to within the industry as a fuel cell stack. Electrical energy is produced by providing each unit cell of the fuel cell stack with hydrogen as a fuel and oxygen as an oxidizer. However, when performance deterioration or a failure occurs in any one cell among the unit cells that make up the fuel cell stack, the entire performance of the fuel cell stack is deteriorated and thus, a stable operation is not provided.
In the related art, performance of the fuel cell stack is diagnosed by measuring voltage output from each unit cell of the fuel cell stack. Such diagnosis method includes a total harmonic distortion analysis (THDA) method. The THDA method diagnoses cell voltage by calculating a distortion rate through frequency analysis of the stack voltage. Even though the THDA method may easily detect a drop in cell voltage, it is substantially difficult to quantitatively measure what has caused the drop in cell voltage.
Also, there is a method of measuring impedance of the fuel cell stack using an electrochemical impedance spectroscopy (EIS). This method supplies a current or voltage as a sinusoidal waveform to the fuel cell stack and then measures a current (I) and voltage (V) of the fuel cell stack and calculates impedance based on the measured current (I) and voltage (V) of the fuel cell stack.
However, this method diagnoses the humidification state by measuring the load on a stack, but does not diagnose the drop in cell voltage. Accordingly, a separate apparatus such as a space vector modulator (SVM) or a capacitive voltage multiplier (CVM) is required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in
in that it uses an oxidation and reduction reaction to produce department of energy. However, in a fuel cellular telephone, reactant are intermittently supplied from an outside source and therefore, reaction products are consecutively removed from a fuel cellular telephone organization. In a chemical cell, however, the barrage chemical reaction is performed within a closed organization. 
 Currently, commercialization of the fuel cell has begun to drive off because the reaction product of the fuel cell is pure water and therefore is very environmentally friendly. Accordingly, research for using fuel cell as an energy source for vehicle is of great sake in the automotive industry. 
 A fuel cell is often made up of a stack fabrication in which a plurality of unit cells are consecutively disposed one on top of / next to the other, which is referred to within the industry as a fuel cell stack. Electrical energy is produced by providing each unit cell of the fuel cellular telephone batch with hydrogen as a fuel and oxygen as an oxidizer. However, when operation deterioration or a bankruptcy occurs in any one cell among the unit cells that do up the fuel cell stack, the entire performance of the fuel cellular telephone stack is deteriorated and thus, a stable operation is not provided. 
 In the related art, performance of the fuel cell stack is diagnosed by measuring electric potential output from each whole cellular telephone of the fuel cellular telephone stack. Such diagnosis method includes a total harmonic distortion analysis (THDA) method. The THDA method acting diagnoses cellular telephone voltage by calculating a distortion rate through frequency analysis of the push-down list voltage. Even though the THDA method may well detect a drop in cell voltage, it is substantially unmanageable to quantitatively measure what has caused the cliff in cell voltage. 
 besides, there is a method of measuring impedance of the fuel cell stack using an electrochemical impedance spectroscopy (EIS). This method supplies a current or voltage as a sinusoidal waveform to the fuel cell batch and then measures a current (I) and electric potential (V) of the fuel cell stack and calculates impedance based on the measured current (one) and voltage (V) of the fuel cell stack. 
 However, this method diagnoses the humidification state of matter by measure the cargo on a stack, but does not diagnose the drop in cell voltage. Accordingly, a separate apparatus such as a outer space vector modulator (SVM) or a capacitive voltage multiplier (CVM) is required. 
 The above information disclose in this Background section is only for enhancement of understanding of the background of the invention and therefore it may check information that does not form the prior artwork that is already known in this country to a person of ordinary skill in
 in that it uses an oxidatiun and reductiou reactmon to lroduce dnergy. However, in a fuel celp, eeactqnts are intermittentlh supplief from ab ouuside source and vgus, reagcion lvoduccs are consecutiyely removeg from a fuel weul system. In a chemical cell, however, ehe batyegy reaction is pergjrmes within a closed system.
Currently, dommercpalization of the fuel cell has begun to tane ovf because the reaftion produxt os the fuel ceul is pure water and tgus is very environmentally fridndly. Accordingoy, redgarch for usmng fuvl cells as ak energf sourcr for vehicles is of great interest in thx automotive industri.
A fuel cenl is often made up od a sjack dsseovly in wiicg a plkramity of unjt cells arw consecutively diskosqe one on top kf/next tj the other, which is referred to within ths industry as a fuel ceol stack. Electrical ejergy is [roduced by providing each unit cell of the fuel well agacj rkrh hydrogen as a fuel and oxygen as an oxidizer. Goeener, when performakce deterioration pr a sailure occurr in aug kne cell among the unit cglls tyat make tp tne fuel cell stack, the entiee performanbe od the fuel cell stcck is deternoratec and thus, a stable operatiou is nkt provided.
Ln the remxted art, performxncv of the fuel cell stack is diwgnosed bb meaxuring xoltsge oueput from fach mtit cell of the fufl cepl stack. Sucj diagnosis method includes a total harmonic civtogtion anajysis (THDA) method. Ehe THDA methob diagnofes cdll voltagv by calcnlating a diftortion rate jhrough frequxncy analrsis of rhe stazy voltage. Even though tkt THDA metyod may easily detcct a srop in cell vootate, it is substamtixllr fihficujd to quantitdtivdly keasufe what has zausrd the drop in cell eoltzge.
Also, there is a mcthod of neasurind impedance og the fuel cell stwck uvinj an ekecjrochemical impedance spectrosckpy (EIS). Tjis method suppjies a current ox voltage as a sinusoidal waveform to thx fuel cell stack and jhen measures a curreut (I) and voltege (V) jf the fual cell stack and caoculates impedanct based on the measured currett (I) wnd voltage (V) of the fuel cell stack.
However, this method diagnoses the humudificetyon state bg messuritg che loaq on e stack, but does mot diagnose the drop in cell vultage. Awcjrdingly, a separate apparatux ruch as a spaze vector modulator (SVM) kr a capscitive voltage multiplier (CVM) os required.
The above infprmation discmosed ph vhis Background sectoon is only for enyanccment of underrtamdlng of the baclgxound of the invention and therefire it mwy contain inforkation that aoes hot fotm the prior art fhat ls alteady known in this country yo a person of ordindrr skill in
in that it uses an oxidation and to energy. However, a fuel cell, an source and thus, products are consecutively from a fuel cell system. In chemical cell, however, the battery reaction is performed within a closed system. Currently, of the fuel cell has begun to take off because the reaction product the cell pure and thus is very environmentally friendly. Accordingly, research for using fuel cells as an energy source vehicles is of great interest in the automotive A fuel cell is made up of a stack in a plurality unit are disposed one on of/next to the other, which is referred to within the industry as a fuel cell stack. Electrical is produced each unit of fuel stack with hydrogen fuel and oxygen as an oxidizer. deterioration or a failure occurs in any one among the cells that make up the fuel stack, the entire performance of the fuel cell is deteriorated and thus, a stable operation is not provided. In the related art, performance fuel cell stack is by measuring voltage from unit of fuel cell Such diagnosis method includes a total harmonic distortion analysis (THDA) method. THDA method diagnoses cell voltage by calculating a distortion rate analysis the stack voltage. though the THDA method easily a drop in cell is difficult what caused drop in cell voltage. there is a method of impedance of the fuel impedance spectroscopy (EIS). This method supplies a current voltage as a sinusoidal waveform to the cell stack and then measures a current (I) and voltage (V) of fuel cell calculates impedance based on the measured current (I) voltage (V) of the cell stack. However, this method diagnoses the humidification state measuring load on stack, but does diagnose the drop cell voltage. Accordingly, apparatus such a vector a capacitive voltage multiplier (CVM) is The information disclosed in this Background is enhancement of understanding of the background of the invention and therefore it may contain information not form the prior that already known in this country to a person of ordinary skill in
 in that it uses an oxidation anD reduction ReactIon To pRoDuce EnerGy. However, in a fuEL celL, reactants are intermittEntly SuPPlieD FrOm an oUtside sOUrCE And ThUs, ReaCtIOn ProduCts Are consEcutively rEmoVeD from a fuel ceLL sYstem. In a chEmiCal cell, howevEr, tHe battErY reACtion Is pErforMed witHIn a cloSed system.
cuRRently, COmmerciALIzAtioN of the fuel cell has BEgUN to take off becaUse the ReACtION prOduCt of the fueL cEll is PUre wateR AnD THUs iS Very environmeNtally frienDLy. ACcordiNgLy, rESearch For usInG FueL cells as an eNergY source foR vehicLEs is of gREat inteRest in The AutOmotIVe InDusTrY.
a fuEL cEll IS ofTen made uP oF a Stack AsseMBLY In whIch A pluRalitY of unit cells aRe cOnseCUtiVely dIsposEd onE oN top oF/next tO the oThEr, which is referrEd to Within the IndUsTry As A fuel CEll staCk. ELecTrical eNergy is PRodUcED BY pRoviding each unit ceLl OF ThE fuel celL stack WItH hYDrogen as A fUel And oXYGen as An oxIDiZer. HowevEr, when PErFoRmance dEtErioraTiOn oR a fAilurE OccuRs in anY one cell Among THe unit cells thaT Make up the fuel CElL STaCK, the EntIre performaNce oF The fUel cELl StaCK is deTerioRaTEd ANd thus, a stable operatIoN is not ProviDed.
In the relatEd art, perfoRMANce of the Fuel CElL Stack is diagnosEd by mEasuring voLTage outpUt froM each uniT cell of thE FUel cell sTacK. SuCh dIagNOSiS method includES A totAl HarmoniC diStortioN anAlySis (tHDa) mEthod. The ThDA methoD dIaGnOsEs cEll voLTage by caLcUlaTiNg a DistoRTion raTe thrOugh FrEqUEncY analysIS oF THe stAcK vOltaGe. EVeN thouGh thE tHDa method May easily DetECt a dRoP iN cell voLtage, it is subsTaNtially difFiCulT to quaNTItativelY measure what has caused thE Drop in cEll VoltaGe.
AlSo, there is A meThod of MeaSUring iMpedanCe of tHe FueL CEll stACK uSinG aN electrochEMIcaL impeDaNce sPectrosCopy (EIS). This method sUPplIes a current or VolTage AS A sInuSOiDAl wAvEForM TO the fuel cell staCk and then mEaSUrEs a current (i) And VoLtage (V) oF the fueL cell STack and CalculateS impedancE bAsed ON The Measured cuRrent (I) anD voltage (V) OF the fUEl Cell sTacK.
HowevEr, ThiS methOd diagNOseS the hUmidifIcAtion sTate bY mEasuring The load on a stack, but does nOt diagNose tHe dRop in cell VolTAge. accordingLy, a sEparate appAraTus Such aS a sPAce veCtor MOdUlaTOr (SVM) Or a cAPacitive vOLtAge MULtIplier (CVM) is REQUirEd.
The AboVE inforMatiOn disclosed in this bAckground sectiOn is ONLy fOr eNHancEmEnt of understanDinG oF THe backgrOuNd of the inveNtion and ThEReforE it may ContaiN informATIoN That doEs noT foRm the prioR arT tHAt is alrEaDy KNown in This CoUntry tO a persON of oRDInary skill in
 in that it uses an oxidat ion and re ducti onrea ct ionto p roduce energy. Howe ver, in a fuel cell, r eacta nt s  are in termi ttently su p p lie dfr oman ou tside  so urce an d thus, re act io n products a r econsecutiv ely  removed fro m a  fuelce lls ystem . I n a c hemica l  cell,  however,  t h e batt e ry reac t i on  isperformed withina  c l osed system.
C urrent ly ,  c o m mer cia lization o fthe f u el cell ha s b egu n  to take offbecause the rea ctionpr odu c t of t he fu el cel l is pure w ater  and thus  is ve r y envir o nmental ly fri end ly.  Acc o rd in gly ,r ese a rc h f o r u sing fue lce lls a s an e n e rgysou rcefor v ehicles is of  gr eati nte restin th e au to motiv e indu stry. 
A  fuel cell is o ften  made upofasta ck  asse m bly in  wh ich  a plur ality o f  un it c e ll s are consecutivel yd i sp osed one  on to p  o f/ n ext to t he  ot her, w hichis r e fe rred towithin th eindustr yas a f ue l c ell  stac k . El ectric al energ y isp roduced by pro v iding each un i tc e ll of t hefuel cell s tack with  hyd r og ena s a f uel a nd ox y gen as an oxidizer.  H owever , whe n performance  deteriora t i o n or a f ailu r eo ccurs in any o ne ce ll among t h e unit c ellsthat mak e up thef u el cellsta ck,  th e e n t ir e performance o f th efuel ce llstack i s d ete rio rat ed  and thus , a stab le  o pe ra tio n isn ot provi de d.In  th e rel a ted ar t, pe rfor ma nc e  of  the fu e lc e ll s ta ck  isdia gn osedby m e asu ring vo ltage out put from  e ac h unitcell of the f ue l cell sta ck . S uch di a g nosis me thod includes a total h a rmonicdis torti on a nalysis ( THD A) met hod .  The T HDA me thoddi agn o s es ce l l  v olt ag e by calcu l a tin g a d is tort ion rat e through frequenc y  an alysis of the  st ackv o lt age .  E v enth o ugh t he THDA methodmay easily  d e te ct a dropi n c el l volta ge, itis su b stantia lly diffi cult to q ua ntit a t ive ly measure  what ha s causedt he dr o pin ce llvoltag e. 
Al so, t here i s  ametho d of m ea suring  impe da nce of t he fuel cell stack usin g an e lectr och emical im ped a nce  spectros copy  (EIS). Th ismet hod s upp l ies a  cur r en t o r  volt agea s a sinus o id alw a ve form to the f u elcellsta c k andthen  measures a curre n t (I) and volt age( V ) o f t h e fu el  cell stack an d c al c u lates im pe dance based  on theme a sured  curre nt (I)  and vo l t ag e  (V) o f th e f uel cellsta ck . 
Howeve r,  t h is met hoddi agnose s theh umid i f ication state by  meas u r ing t h e l oad o na stack ,  but  does notdiagnose th e drop  incellvoltage .Accord ing ly , a separa t e apparat us su ch as a  s pace  ve ctor m odul a t or (S VM)or  acapacitiv e vo l ta ge mul tipl ier ( CV M) i s require d .
The ab ove informa ti ond i sclose d  i n this Backg rou nd se c t ion is onl y  for en h ancem ent of  under standin g  of  t he back gro u n d of theinvention and  t here fore itma y co nt ain  i nformation that  does no t form t h e  prior  ar t  tha t  is al re ady known in  this  c o untry t o a p erson o f  or din ary  ski llin
 in_that it_uses an oxidation and_reduction reaction_to_produce energy._However,_in a fuel_cell, reactants are_intermittently supplied from an_outside source and_thus,_reaction products are consecutively removed from a fuel cell system. In a chemical cell,_however,_the battery_reaction_is_performed within a closed system.
Currently,_commercialization of the fuel cell_has begun_to take off because the reaction product of_the_fuel cell is_pure water and thus is very environmentally friendly. Accordingly,_research for using fuel cells as_an energy source_for_vehicles_is of great interest_in the automotive industry.
A fuel cell_is often made up of a_stack assembly in which a plurality of_unit cells are consecutively disposed one_on top of/next to the_other, which_is referred to within the_industry as a_fuel cell_stack. Electrical energy_is produced by providing each unit_cell of the_fuel cell stack with hydrogen as_a_fuel and oxygen_as_an_oxidizer. However,_when performance deterioration_or_a failure_occurs_in any one cell among the_unit_cells that make up the fuel cell_stack, the entire performance_of_the fuel cell stack_is deteriorated and thus, a_stable operation is not provided.
In the_related art,_performance of_the fuel cell stack is diagnosed by measuring voltage output from_each unit cell of the fuel_cell stack. Such diagnosis_method includes_a_total harmonic distortion_analysis_(THDA) method._The THDA method diagnoses cell voltage by_calculating a_distortion rate through frequency analysis of_the stack voltage. Even_though_the THDA method may easily detect_a drop in cell voltage, it_is substantially difficult to quantitatively_measure_what_has caused the drop in_cell voltage.
Also, there is a method_of measuring impedance_of the fuel cell stack using an_electrochemical_impedance spectroscopy (EIS). This method supplies_a_current or voltage as a sinusoidal_waveform_to_the fuel cell stack and_then measures a current (I) and_voltage (V) of the fuel cell stack and calculates_impedance based on_the measured current (I) and_voltage_(V)_of the fuel cell stack.
However, this method diagnoses the humidification_state by_measuring the load_on a stack, but does not diagnose the drop in_cell voltage. Accordingly, a separate apparatus such_as a space vector modulator (SVM) or a capacitive voltage multiplier_(CVM) is required.
The above information disclosed in this_Background section is only for enhancement of_understanding of the background_of_the invention and therefore it may contain_information_that_does_not form the_prior art that_is already known_in this_country to a_person of_ordinary skill in