• 한국정밀공학회지
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• 제14권10호
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• pp.50-57
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• 1997

A fast tool servo (FTS) for diamond turning improves machining accuracy by quickly compensating relative position errors between the cutter and the workpiece. Therefore, the FTS needs to have large band-width with good tracking performance. Serious hysteresis nonlinearity of PZT actuators used in the FTS, however, deteriorates fast tracking performance. Several types of feedforward hysteresis compensators and feedback controllers are tested to improve tracking performance. Through simulations and experiments, control structure which yields the smallest tracking error is selected. The maximum peak to peak error in tracking a sinusoidal waveform is reduced by one fifth compared to that of a regular PID controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.660-662
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• 2000

It is demonstrated that the torque performance of the flux barrier type synchronous reluctance motor(SynRM) can be improved in terms of geometric parameters. Torque ana power factor are related to the difference of inductances and the saliency ratio. And these inductance characteristics are determined by the geometric parameters of rotor: the number of layers. the width of iron to the width of flux barrier($K_w$). slot number and shape, airgap, bridge, etc. The relationship between geometric parameters. especially, $K_w$ and motor performance will be studied. This paper shows that torque and power factor are improved through redesign with considering geometric parameters. Performance comparisons of proto type SynRM and improved SynRM are given by FEA(Finite Element Analysis).

• 설비공학논문집
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• 제1권3호
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• pp.219-227
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• 1989

Performance analysis of an absorption heat pump system for solar energy recovery has been done by computer simulation to find improved working pairs. Based on the thermodynamic analysis, the coefficient of performance and mass flow ratio have been calculated to compare two aqueous solutions [LiCl-water, $LiCi-CaCl_2-Zn(NO_3)_2$-water] which were developed for cooling by others, with the conventional LiBr-water solution. As a result of this analysis, the performances of the new aqueous solutions were found to be better than that of LiBr-water solution not only in cooling systems, but also in heating and in heat transformer systems. Their theoretical thermodynamic performance data were given here with.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.321-324
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• 2010

최근 멀티코어 프로세서의 이용이 증가함에 따라, 멀티코어를 이용한 다양한 병렬화 기법들이 제안되고 있다. 모바일 환경에서도 멀티코어 구조를 적용한 프로세서들이 등장하면서 병렬화 기법들이 연구되고 있다. 하지만, 아직까지 모바일 환경에서의 CPU의 성능은 한계가 있다. 이를 병렬처리와 실수 연산이 뛰어난 GPGPU(General-Purpose computing in Graphics Processing Units)를 멀티코어 구조로 설계함으로써 다른 전용 하드웨어의 추가 없이 성능을 향상 시킬 수 있다. 본 논문에서는 모바일 환경에 적합하게 설계된 멀티코어 GPGPU를 이용하여 H.264 디코더의 Inverse Quantization, Inverse DCT, Color Space Conversion 모듈을 구현하였다. 멀티코어 GPGPU를 이용한 H.264 전체 시스템 동작 시 50%의 성능 향상이 있었다.

• 유기물자원화
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• 제9권3호
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• pp.136-144
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• 2001

악취중 황화수소의 생물학적 제거시스템에서 바이오필터의 미생물 담체로 유기담체인 Peat와 Rock wool을 사용하고 미생물원으로 소화 슬러지를 식종했다. 유입 황화수소 농도를 증가시켜 완전히 제거되는 황화수소의 유입 부하를 완전 제거능, 제거를 보여준 최대의 제거량을 최대 제거능으로 정의하였다. 단위 중량 및 단위 체적 기준으로 비교한 완전 제거능 및 최대 제거능은 Peat보다 Rock wool의 결과가 높았다. 동력학적 반응속도 해석에 의한 황화수소의 최대 제거속도($V_m$) 및 포화정수($K_s$)를 이용한 속도해석 결과는 황화수소의 농도가 증가할수록 Rock wool의 반응속도가 빠르게 진전되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제22권8호
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• pp.1174-1179
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• 2009

An experiment was conducted to study the effect of post-hatch feed deprivation on yolk sac utilization andsubsequent performance of young broiler chickens (280) up to 35 days of age. The experimental treatments included access to feed at 8 h intervals after hatch, up to 48 h (0, 8, 16, 24, 32, 40 or 48 h). Water was offered ad libitum to all the groups immediately after placement. Results indicated that chicks with access to feed immediately after hatch used up the residual yolk more quickly. Access to feed between 8-24 h post-hatch, supported faster utilization of residual yolk compared to those chicks that remained unfed for 40-48 h (p<0.05). Further, deprivation of feed up to 24 h did not alter the lipid and protein contents in residual yolk, but fasting of chicks beyond 24 h (32, 40 and 48 h) led to retention of higher lipid and lower protein content in the yolk sac (p<0.05). At 7 days of age, the weights of proventiculus and gizzard were not affected by feed deprivation up to 48 h. However, the liver, pancreas and jejunum recorded significantly (p<0.05) heavier weights in chicks that were fed during the initial 24 h period compared to delayed feeding (32-48 h). Chicks fed within 24 h after hatch gained significantly (p<0.05) higher weight at 5 weeks of age than those that received feed between 32 and 48 h. Feed deprivation for 48 h was more detrimental to growth than 24-40 h. This study revealed the significance of early posthatch feeding (<24 h) on faster utilization of yolk sac nutrients and optimum development of intestines and organs, culminating in improved weight gain (>10.5%) of broilers at 5 weeks of age.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.146-151
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• 2013

본 연구에서는 연료극 또는 공기극에 함유된 불순물인 황화합물의 도입을 차단할 수 있는 GDL을 제조하여, 이를 평가용 단위전지에 체결하여 $H_2S$와 $SO_2$를 연료극과 공기극에 각각 동시에 공급하여 PEMFC의 성능 저하 및 회복에 관한 연구를 수행하였다. 그 결과 $H_2S$와 $SO_2$의 농도가 증가함에 따라 전지의 성능이 감소하며 특히 10 ppm 이상의 농도에서는 10분 이내에 약 10-15% 정도 성능이 감소하였다. 특히 GDL 표면의 기공이 없는 CN-2 GDL을 체결한 단위전지의 경우 피독에 의한 성능 감소 속도가 더 빠른 것을 확인하였다. 그리고 단위전지 피독 후 황화합물이 혼합되지 않은 순수 가스를 1시간 이상 공급하였을 때 전지의 성능이 GDL의 종류에 따라 90%에서 95% 이상 회복되며 CN-1 GDL의 경우가 가장 회복이 우수하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.559-562
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• 2004

The $high-T_c$ Superconducting(HTS) antenna which consists of "H" type resonator has the benefits for the miniaturization of antenna in comparison with the microstrip antenna of the similar dimension. To fabricate the "H" type antenna HTS $YBa_2Cu_3O_{7-x}$(YBCO) thin films were deposited on MgO substrates using rf-magnetron sputtering. Standard etching processes were performed for the patterning of the "H" type antenna. For comparison between normal conducting antennas and superconducting antennas, the gold antennas with the same dimension were also fabricated. An aperture coupling was used for impedance matching between $50\Omega$ feed line and HTS radiating patch. The diverse experimental results were reported in terms of the resonant frequency, the return loss and the characteristics impedance. The "H" type superconducting antenna showed the performance of 1.36 in SWR, 24 % in efficiency, and 14.6 dB in the return loss superior to the normal conducting counterpart.

• 설비공학논문집
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• 제11권1호
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• pp.48-60
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• 1999

An experimental study on the performance enhancement of a screw-compressor-type chiller with 100kW of nominal cooling capacity has been carried out. Performance test facility was developed to investigate the effects of a partial modification from the existing chiller on the performance. By replacing the existing shell-and -tube heat exchangers with plate heat exchangers, the cooling capacity is increased by 15~18% and the COP is also increased by 19~21% depending on the operation temperature range. Charging mixed refrigerant R22/R142b(80 : 20) instead of R22 into the chiller with plate heat exchangers improves the cooling capacity by 4% and the COP very largely by 30%. Each contribution of the plate evaporator, plate condenser, and mixed refrigerant to the performance enhancement is examined by analyzing the refrigeration cycle and the heat transfer processes. It is also shown that the chiller performance can be improved by adapting 2-stage-compression cycle using an economizer.

• Environmental Engineering Research
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• 제11권5호
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• pp.285-291
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• 2006

Biofiltration is a simple, effective, economically viable and the most widely used gas treatment technique for treating malodors at low concentrations and high flow rates. This paper reports the performance of two lab scale immobilized cell biofilters operated in continuous mode for hydrogen sulfide ($H_2S$) and ammonia ($NH_3$) removal. The removal efficiency (RE, %) and the elimination capacity (EC, $g/m^3{\cdot}hr$) profiles were monitored by subjecting the biofilters to different loading rates of $H_2S$ (0.3 to $8\;g/m^3{\cdot}hr$) and $NH_3$ (0.3 to $4.5\;g/m^3{\cdot}hr$). The removal efficiencies were greater than 99% when inlet loading rate to the biofilters were upto $6\;gH_2S/m^3{\cdot}hr$ and $4\;gNH_3/m^3{\cdot}hr$ respectively. The performance of the biofilters were also ascertained by conducting shock loading studies at a loading rate of $10\;gH_2S/m^3{\cdot}hr$ and $6\;gNH_3/m^3{\cdot}hr$. The results from this study show high removal efficiency, good recuperating potential and stability of the immobilized microbial consortia to transient shock loads.