• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.6
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• pp.607-613
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• 2010

A seawater distiller, in which the waste heat from a portable electric generator was used, with a multiple-effect diffusion still was designed. The waste gas from small generators commonly used in islands has not yet been used because it has less thermal energy; however, this waste gas can be used as a heat source for small-capacity distillers and as an additional heat source for solar stills. The proposed distiller comprises a series of closely spaced parallel partitions that are placed in contact with saline-soaked wicks. In the distiller, evaporation and condensation processes are repeated to recycle the thermal energy for increasing the distillate productivity. Experimental results show that the proposed distiller with only one-effect still can produce at least 6.7 kg/day of distilled water; the proposed distiller with a ten-effect still is expected to produce 43 kg/day of distilled water. This amount of distillate is approximately four times the maximum daily productivity of the solar stills, as determined in outdoor experiments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.15-20
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• 2015

The objective of this study was to examine numerically the heat transfer and flow characteristics of the heat pipe with a wick using the simplified heat transfer model to enhance the cooling effects of high heat flux devices and minimizing the energy consumption for electric vehicles. The heat pipe with a wick was analyzed using commercial software with COMSOL and water was used as the working fluid. The velocity and temperature characteristics of the heat pipe were simulated numerically along the heat pipe and the local and average Nusselt numbers were calculated. As a result, the driving force occurred because of the temperature difference between the hot side and the cold side. The heat transfer of the heat pipe occurred from the hot side to the cold side and increased toward the center position. In addition, the average Nusselt numbers were 1.88 for the hot side and 0.1 for the cold side, and the maximum Nusselt number was 4.47 for the hot side and 0.7 for the cold side.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.653-658
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• 2004

Failures in optical networks that have huge transmission capability provoke service discontinuitH and thus large economical damage. Even though many algorithms are proposed for protection and restoration on a single failure, there are few algorithms for multiple failures. Eulerian tour is known to be effective to protect and restore a single failure in the literature. This paper proposes an algorithm that can perform efficient protection and restoration for multiple failures based on combined Eulerian tours. The proposed one is very effective on protection and restoration in general cases with two failures, and the comprehensive computer simulation shows that the restoration rate increases up to about 90%.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.4
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• pp.485-492
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• 2006

This paper deals with implementation of network for distributed control system of a humanoid robot ISHURO(Inha Semyung Humanoid Robot). A humanoid robot needs much degree of freedom structurally and much data for having flexible movement. To realize such a humanoid robot, distributed control method is preferred to the centralized one since it gives a compactness, modularity and flexibility for the controllers. For organizing distributed control system of a humanoid robot, a control processor on a board is needed to individually control the joint motor and communication technology between the processors is required to transmit its information within control time. The processor is DSP-based processor and includes CAN network on a chip. It shares the computational load such as monitoring the sensor information and controlling the actuator between each of modules. In this paper, the communication architecture is suggested and its message protocol are discussed including message structure, time consumption for transmission, and controller structure at the view of distributed control for a humanoid robot. All of the sequence are simulated with Matlab and then verified with real walking experiment by ISHURO.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.479-482
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• 2006

The most the electronic industry has recently accelerated the modularization, the miniaturization and the high integrated trend of electronics fields such as electronics components, appliances and etc., the most increasingly the heat generation problem rises. Even though the conventional cooling technologies are widely used in order to reduce the heat loads, the technologies are not easy to meet the present trends due to the fact that most of many conventional methods are relative to external form environments such as size, design and so on. With regardless of those environments, however, a heat pipe is one of the most efficient systems to improve the heat transfer performance. And then the performance of the heat pipe depends on a wick structure. Of various wick structures, sintered metal wick is known so that it has some advantages such as smaller pore size, increasing porosity as well as high reliability. In this study sintered metal wicks, thickness 0.7 mm, 0.8 mm and 0.9 mm, were manufactured as of $100{\mu}m$ copper powder to obtain the manufacturing technology of heat pipes mounted with a sintered metal wick. Furthermore, experiments for the operational performance factors such as capillary limit, thermal resistance were not only performed but also compared with a theoretical model simultaneously. Experimental results agreed with the theoretical model, and then it seems to be required to study various development processes of sintered metal wicks for the high performance of a heat pipe system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.7
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• pp.599-607
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• 2015

In this study, we theoretically investigate the thermal performances of heat pipes that have different nano-fluid properties. Two different types of nano-particles have been used: $Al_2O_3$ and CuO. The thermal performances of the heat pipes are observed for varying nano-particle aggregations and volume fractions. Both the viscosity and the conductivity increase as the volume fraction and the aggregation increase, respectively. Increasing the volume fraction helps increase the capillary limit in the well-dispersed condition. Whereas, the capillary limit is decreased under the aggregate condition, when the volume fraction increases. The dependence of the heat pipe thermal resistance on the volume fraction, aggregation, and conductivity of the nano-particles is analyzed. The maximum thermal transfer of the heat pipe is highly dependent on the volume fraction because of the high permeability of the heat pipe. For the proposed heat pipe, the optimum volume fraction of the nano-particle can be seen through 3D graphics.

• Composites Research
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• v.30 no.1
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• pp.52-58
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• 2017

This paper presents the optimum design methodology for composite wing structure which automatically calculates the safety margin using optimization framework integrating failure modes. Particularly, its framework is possible to optimize sizing procedure to prevent failure mode which has the greatest effect on reducing the sizing time of composite structure. The main failure mode was set as the first ply failure, buckling failure mode, and bolted joint stress field, and the margin was calculated to minimize the weight. The design variable is a laminate sequence database and the responses are strain, buckling, bolted joint stress field. The objective function is the mass of the wing structure. The results of buckling analysis were compared using the finite element model to verify the robustness and reliability of Composite Optimizer.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.1
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• pp.73-80
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• 1991

인류가 산업발전 등으로 인해 석유등 화석연료를 사용함에 따라 대기오염은 날로 악화되어 1952년 런던스모그 같은 참사를 맞이하였고 이에 각국은 이러한 대기 오염물질을 저감하기 위하여 노력한 결과 대기 오염물질은 낮아지고 있으나 이에 반해 이산화탄소 배출량 증가에 따른 지구 온난화 현상과 오존층 파괴는 지역적인 환경문제에서 번세계적인 환경문제로 확산 전개되고 있다. 특히 산업혁명후 화석연료의 급격한 사용증가로 인한 이산화탄소 배출량 증가는 지구를 온나화시키고 수십년 후에는 환경에 심각한 영향을 주게 되는 것은 의심할 여지가 없는 것으로 이는 지구환경문제 중에서 금회 최대의 과제로 대두되게 되었다. 이에 따라 1985년 UNEP 관리 이사회를 필두로 "지구환경보전에 관한 동경회의", "대기오염 및 기후변동에 관한 노드윅 회의", "백악관회의", "휴스톤 Summit" 등에서 이 문제가 거론되기 시작하여 '90. 8월에는 스웨덴에서 온난화에 대한 과학적 인식과 대책의 메카니즘을 정하기 위한 IPCC 4차 회의가 각국 대표들이 참석한 가운데 정치, 경제, 과학의 문제로 등장하여 우리생활의 근본을 좌우할 다각적인 논의가 진행된 바 있다. 또한 미국, 영국, 일본 등 선진국들의 정상이 모이는 G7 회담 등에서 논의되고 있는 것들 중 정치적인 문제를 제외하고는 환경문제를 가장 많이 다룬다는 외신보도를 우리는 여러번 접한바 있다. 현재 국제적 환경문제로 가장 관심이 집중되고 있는 문제 중 몇가지를 소개하면 우선 <몬트리올의 정서에 의한 오존층 보호>를 들 수 있겠고, 최근 국제 협약 제정을 추진하고 있는 "지구온난화 방지에 관한 기후협약" 그리고 유해폐기물의 국제교역에 관한 "바젤협약"과 함께 새로이 제기된 "생물학적 다양성 협약"등이 거론되고 있으며, 이에 덧붙여 미국의 "자동차배출가스 규제"도 우리나라 산업에 큰 영향을 미칠 것으로 판단된다. 본 논문은 이중 대기와 관련된 오존층 보호와 지구온난화 대책에 대한 국제회의 등에서 현재까지 논의되었거나 토의될 내용에 대하여 기술하고 특히 금년부터 집중적으로 국제협상이 진행될 지구온난화 문제에 대한 최근의 국제동향 우리나라의 입장을 기술하고자 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.7
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• pp.528-534
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• 2011

In this paper, thermal characteristics of cylindrical grooved wick heat pipes with water-based MWCNT nanofluids as working medium are experimentally investigated. Volume fractions of nanoparticles are varied with 0.1% to 0.5%. Transient hot wire method developed in house is used to measure the thermal conductivity of nanofluids. It is enhanced by up to 29% compared to that of DI water. The thermal resistances and temperature distributions at the surface of the heat pipes are measured at the same evaporation temperature. The experimental results show that the thermal resistance of the heat pipes with water-based MWCNT nanofluids as working fluid is reduced up to 35.2% compared with that of heat pipe using DI water. The reduction rate of thermal resistance is greater than the enhancement rate of thermal conductivity. Finally, based on the experimental results, we present the reduction of the thermal resistances of the heat pipes compared with conventional heat pipes cannot be explained by only the thermal conductivity of water-based MWCNT nanofluids.

• Solar Energy
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• v.15 no.2
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• pp.3-11
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• 1995

This paper reports the performance of solar domestic hot water systems manufactured with heat pipes. A series of tests were conducted on a number of systems to elicit the most suitable configuration of the system for possible commercialization in Korea. The heat pipe is made with a copper tube and the respective length of the evaporator, adiabatic, and condenser sections are 1700mm, 100mm and 200mm. The evaportor section is finned with a copper plate to increase solar input for its proper operation as a heat pipe. Results show quite an interesting performance data stemming from the difference in working fluids, presence of wick, and other various design parameters associated with the collection and utilization of solar energy.