• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.65-68
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• 2006

Experiments were performed to investigate the effects of mud-flap width on the aeroacoustic noise generation inside high-speed trains. The open-circuit type wind tunnel was used. The measurement setup was custom-built to simulate intercoach spacing. From the measurements, the characteristics of the turbulent flow after the intercoach spacing and consequent generation of aeroacoustic noise inside the cabin was investigated. Especially the effects of mud flap length on the characteristics of the characteristics of the turbulent flow were identified. The mechanism of noise generation by analyzed interactions with structure vibration characteristics and generation characteristics of blocked pressure was investigated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.243-244
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• 2009

The $TiO_2$ nanofiber doped $TiO_2$ electrode area applied to dye-sensitized solar cells(DSSCs). The mixtures of $TiO_2$ nanofiber to $TiO_2$ photoelectrode has larger surface area than $TiO_2$ photoelectrode. In this research added 2.5, 5 and 10wt% $TiO_2$ nanofibers and the optimum condition of 5 wt% $TiO_2$ nanofiber's high surface area contributing the improvement of short-circuit photocurrent. The open-circuit voltage was 0.7V and solar energy conversion efficiency was 5.4%.

• 대한전기학회논문지:전력기술부문A
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• 제49권1호
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• pp.26-30
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• 2000

Switching of the transmission lines(T/L) is one of the methods for wuppressing the short circuit capacity. This paper presents the T/L switching operation by using the Hopfield neural network(HNN). The switching of T/L can make the line powers and the bus voltages deteriorated, as well as the fault current decreased. Such an insecure state should be avoided when the T/L is operated to be open. In this studies, the inequality constraints are formulated into the objective function to be incorporated with the HNN. Test results show that the convergence characteristics of HNN lead to the adequate solution of T/L switching.

• 한국전기전자재료학회논문지
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• 제23권3호
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• pp.250-259
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• 2010

The ability for energy harvesting via the piezoelectric effect was studied for a unimorph element such as piezo buzzer. A simple equivalent circuit was proposed to predict the energy generated based on the internal stress. Unimorphs with a metal-cavity were used as a driving device of the generation panel. Both the AC open voltage and DC output voltage as a function of pressure period and number of element were measured. For the unimorph generation circuit, DC output voltage varies with pressure period, reaching a maximum value at $470{\mu}F$. The maximum output voltage a according to load resistance was measured at $1M{\Omega}$. Data analysis of the DC output voltage and time constant indicated that number of piezoelectric element of optimum was 60~80. It was found that piezoelectric unimorph has the possibility to be used as the driving element of the electric generation.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.289-290
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• 2006

We report a study of Zn(S)Se/GaAs heterojunction solar cells grown by molecular beam epitaxy (MBE). Zn(S)Se/GaAs heterostructures prepared under different conditions were characterized in-situ by reflection high-energy electron diffraction (RHEED). Structural and electrical properties were investigated with double crystal X-ray diffraction and current-voltage characteristics, respectively. The fabricated $n-ZnS_{0.07}Se_{0.93}/p-GaAs$ solar cell (SC #2) exhibited open circuit voltage($V_{oc}$) of 0.37 V, short circuit current($I_{sc}$) of $1.7{\times}10^{-2}$ mA, fill factor of 0.62 and conversion efficiency of 7.8 % under 38.5 $mW/cm^2$ illumination.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.181-184
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• 2001

A coplanar waveguide(CPW) on a dielectric substrate consists of a center strip conductor with semi-infinite ground planes on either side. This type of waveguide offers several advantages over microstrip line. It facilitates easy shunt as well as series mounting of active and passive devices. It eliminates the need for wraparound and via holes, and it has a low radiation loss. These, as well as several other advantages, make CPW ideally suited for microwave integrated circuit applications. However, very little information is available in the literature on models for CPW discontinuities. This lack of sufficient discontinuity models for CPW has limited the application of CPW in microwave circuit design. We presented for the characteristics of coplanar waveguide open end capacitance and series gap capacitance. Measurements by utilizing the resonance method were made and the experimental data confirmed the validity of theories. The relationships between the CPW capacitances and the physical dimensions were studied.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.441-441
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• 2014

The characteristics of hybrid conductive films based on multilayer graphene and silver grid have been investigated for the high-performance and flexible organic solar cells. The hybrid conductive films have been prepared on glass and polyethylene terephthalate (PET) substrates using conventional photolithography process and transfer process of graphene. The optical and electrical properties of prepared conductive films show transmittance of 87% at 550nm and sheet resistance of $28{\Omega}/square$. The electromechanical properties were also investigated in detail to confirm the flexibility of the hybrid films. OSCs have been fabricated on the hybrid conductive films based on graphene and silver grid on glass substrate. The power conversion efficiency of 2.38%, a fill factor of 51%, an open circuit voltage of 0.58V and a short circuit current of $8.05mA/cm^2$ were obtained from the device on glass substrate. The PCE was enhanced 11% compared with OSCs on the MLG films without silver grid.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.324-328
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• 2001

This paper presents parallel operation and control loop design of ZVT(Zero Voltage Transition) Full Bridge DC/DC Converter. At parallel operation of ZVT Full Bridge Converter, dynamic current shared inductor devides the same current of unit converter and ZVT circuit and aids to high efficiency in the system. Base on the modeling of ZVT. Full Bridge Converter, the control loop is designed using a simple two-pole, one-zero compensation circuit. To show the validity of the design procedures, the small signal analysis of the closed loop system and open loop system is carried out and the superiority of the dynamic characteristics is verified through the experiment with a 2kW, 50kHz prototype converter.

• 한국항해항만학회지
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• 제30권7호
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• pp.607-610
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• 2006

A new compact microstrip low-pass filter and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

• 대한안전경영과학회지
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• 제4권2호
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• pp.199-207
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• 2002

The polycrystalline CdS of large scale were grown by chemical pyrolysis deposition for $Cu_2$S/CdS heterojunction solar cells. For high quality CdS polycrystalline thin films, the chemical solution was deposited on indium tin oxide(ITO) glasses at the temperature of 50$0^{\circ}C$ for 15 second and annealed at 35$0^{\circ}C$ for 20 minute or 50$0^{\circ}C$ for 30 second. To fabricate high efficiency solar cells, optical and electrical properties, morphology by SEM and x-ray diffraction on polycrystalline CdS thin films were investigated. From the I-V characteristics of $Cu_2$S/CdS heterojunction, the open circuit voltage, $V_{oc}$ was 0.7 V and the short circuit current, $I_{sc}$ was 4.2 mA. We found that the fill factor(FF) was 0.5 and the efficiency was 2.5%.