• 설비공학논문집
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• 제6권4호
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• pp.354-364
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• 1994

Experiments have carried out to investigate the effects of parameters, such as mass ratio of R141b-to-water, stirrer speed, brine inlet temperature, brine flowrate, and additives, on the performance of the cool storage system using R141b clathrate. The cool storage system in this experiment was composed of storage tank, refrigerator, and heater. The results show that the mass ratio of R141b-to-water, 1 : 3~1 : 3.5 gives the best performance and the stirring speed has optimum point as 600rpm. At this speed impeller Reynolds number is $1.01{\times}10^5$. The lower the inlet brine temperature and the highter the brine flowrate, the better performance. The addition of metal powder turned out to reduce the degree of supercooling. The supercooling reduction was proportional to the amount of the metal power. However when metal powder was added more than 0.1 wt%, there was no additional supercooling reduction. The surfactants shortened the time consumed for cool storage to the half of no surfactant added case.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.215-218
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• 2004

The electrokinetically enhanced soil flushing had a great potential to improve the removal efficiency of polycyclic aromatic hydrocarbons (PAHs) from low permeable soils. A semi-pilot study of surfactant-enhanced electrokinetic process was investigated for the removal of phenanthrene from kaolinite. A nonionic surfactant, Tergitol 15-S-12 at 10 g/L was introduced as a flushing agent and 0.001M of sodium chloride was used as an electrolyte. When the constant voltage of 100 V was applied to the system for 25 days, only 0.66 kWh of electric power was consumed and the amount of electroosmotic flow was 6.9 L. The removal efficiency of phenanthrene was about 40 % and it can be improved by increasing the ion concentration of the flushing solution or the applied voltage.

• 대한기계학회논문집
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• 제13권1호
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• pp.87-95
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• 1989

본 연구에서는 국내산 비규칙성 짧은 섬유로 강회된 SMC 복합재료의 피로파괴 특성에 대한 기초자료로서 피로균열의 진전특성을 나타내는데 기존파괴 역학의 적용여부를 살펴보며, 서로 다른 피로모드 상태 하에서 하중크기의 상태에 따른 피로균열진전의 특성을 나타내었으며, 또한 주사형 전자현미경(scanning electron microscope)을 사용한 파단면 관찰을 통해 파괴 메카니즘을 살펴보았다.

• 한국통신학회논문지
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• 제35권11B호
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• pp.1631-1639
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• 2010

본 논문은 멀티프로세서 임베디드 시스템에서 사용하는 어플리케이션을 구성하는 태스크를 수행하는데 필요한 전력과 태스크간의 의존성에 의해서 발생하는 통신 비용을 감소시킬 수 있는 스케줄링 알고리듬을 제안한다. 제안된 알고리듬은 기존 알고리듬에서는 통신비용은 고려하였으나 스케줄링 단계에서는 동적 전력 관리 결과를 고려하지 않는 점을 보완하여 스케줄링 단계에서 여유시간(Laxity) 사용을 예측하여 동적 전압 관리의 효율을 높이는 방법을 사용한다. 이를 통해 복잡한 멀티미디어 어플리케이션에 동적 전력 관리를 적용하여 수행 시 에너지 효율을 높였다. 실험 결과 멀티미디어 어플리케이션인 HD MPEG4, MotionJPEG codec, MP3, Wavelet 프로그램을 멀티프로세서 환경에서 제안된 알고리듬을 이용하여 저전력 스케줄링 결과 기존 방식에 비해 평균 11.2%의 에너지 감소를 얻었다.

• 설비공학논문집
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• 제26권10호
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• pp.467-473
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• 2014

Since the operating conditions of HVAC systems are different from those for which they are designed, on-going commissioning is required to optimize the energy consumed and the environment in the building. This study presents a methodology to analyze operational data and its applications. A predicted operation model is to be produced through a statistical data analysis using multiple regressions in SPSS. In this model, the dependent variable is the pre-cooling time, and the independent variables include the power output of the supply air inverter during pre-cooling, the supply air set temperature during pre-cooling, the indoor temperature-indoor set temperature just before pre-cooling, supply heat capacity, and the lowest outdoor air temperature during non-cooling/non-heating hours. The correlation coefficient R2 of the multiple regression model between the pre-cooling hour and the internal/external factors is of 0.612, and this could be used to provide information related to energy conservation and operating guidance.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.356-361
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• 2005

Earth brush for electrical multiple units(EMUs) is a device through which the current of the EMU load's consumed power fed from the DC 1,500V overhead line (or from the AC 25.000V catenary) flows via axle to the rail(ground) and which prevents the electric corrosion of the axle bearings by preventing the current flow to the axle bearings caused by electric potential from the magnetic field when the bearings rotate together with the earthing function when a thunderbolt falls or a surge comes. The earth brush wear rates among cars, however, shows quite differences when the earth brushes after being separated from the holders are measured with vernier callipers every 6 months of maintenance period. Main causes of the earth brush wear are divided as mechanical, electric arc and electrical one, and the factors can be running speed, current, harmonics, connection state. spring tension, earth brush material, lubricant and so on. but only the earth brushes of the motor(M1) car show the highest wear rate and moreover maintenance difficulty occurs because of the wear rate differences among e earth brushes in one holder. The reason for these preponderant wear comes from the design concept of making preponderant current flow to some particular earth brushes and moreover the heat generated by the harmonics when the inverter starts to operate accelerate the wear. By defining these causes through experiments. I hope that the found results would be helpful for the future EMU design, safety, economy and maintenance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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• pp.101-102
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• 2006

We investigated the characteristics of flux-lock type superconducting fault current limiter (SFCL) by the fault cycles. Since the recovery characteristics of a superconducting element in the flux-lock type SFCL were dependent on the winding' direction between two coils, the analysis for the recovery characteristics of this type SFCL together with the current limiting characteristic is necessary to apply it to power system. As the fault cycles was increased from 1 cycle to 5 cycles, the initial limiting current ($I_{ini}$) and quench characteristic were mostly same. As the fault period increases, the recovery time of the superconducting element increases. The consumed energy and recovery characteristics in a superconducting element show the same tendency.

• 한국정밀공학회지
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• 제17권1호
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• pp.216-223
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• 2000

A robot arm with free joints has some advantages over conventional ones. A light weight and low power consumed arm can be made by a reduction of the number of joint actuators. And this arm can easily overcomes actuator failure due to unexpected accident. In general such underactuated arm does not have controllability because of the lack of joint actuators. The two-link arm with a free joint introduced in this paper is also uncontrollable in the sense of linear system theory. However, the linearized system sometimes can not represent the inherent dynamic behavior of the nonlinear system. In this paper the dynamic characteristics of the two-link arm with a free joint in view of global motion including damping and friction effect of the joints is investigated. In the case of considering only the damping effect, the controllable goal positions are confined to a specific trajectories. But in the case of considering the friction effect, the system can be controlled to arbitrary positions using the friction of the free joint as a holding brake. Also numerical example of position control is presented.

• 공업화학
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• 제27권2호
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• pp.217-220
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• 2016

식물성 에스트로겐은 내분비계에서 생성되지 않고 식물성 에스트로겐 식물을 먹음으로써 소비되는 유사에스트로겐이다. "식이 에스트로겐"으로도 불리는 식물성 에스트로겐은 자연적으로 발생하는 다양한 식물성 화합물 그룹이며, 에스트로겐과 구조적인 유사성 때문에 갱년기 증상을 감소시킴으로써 건강 증진에 기여할 수 있을 것이다. 본 연구에서는 다양한 식물성 에스트로겐을 고삼, 석류, 칡으로부터 초음파공정을 이용하여 추출하였다. 다양한 초음파세기와 추출시간에서 식물성 에스트로겐의 추출 양을 비교하였다. 이로부터 얻은 결과는 천연물과 관련된 생화학적 연구에 기본적인 정보를 제공할 수 있을 것이다.

• 한국정보통신학회논문지
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• 제11권9호
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• pp.1799-1805
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• 2007

무선 Ad-hoc 네트워크에서의 배터리 고갈에 의해 발생하는 노드 실패는 네트워크 전체의 성능에도 큰 영향을 미치므로 에너지소비를 고려한 라우팅 알고리즘은 매우 중요하다. 본 논문에는 전송 시 노드에 의한 에너지 소비뿐만 아니라 노드의 잔여 에너지와 경로 재설정 시 소요되는 지연까지도 고려한 라우팅 (DEAR; Delay and Energy-Aware Routing) 알고리즘을 제안하였다. 성능분석 결과 DEAR알고리즘은 충분한 잔여 에너지를 보유한 노드로 경로를 설정함으로써 에너지 비율에 따라 균형 있게 에너지를 소비할 수 있었다.