• 한국소음진동공학회논문집
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• 제14권8호
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• pp.675-683
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• 2004

The motor current signature provides an important source of the information for the faults diagnosis of three-phase induction motor. The theoretical principles behind the generation of unique signal characteristics, which are indicative of failure mechanisms, are Presented. The fault detection techniques that can be used to diagnose mechanical Problems, stator and rotor winding failure mechanisms, and air-gap eccentricity are described. A theoretical analysis is presented which predicts the presence of unique signature patterns in the current that are only characteristics of the fault. The predictions are verified by experimental results from a special fault Producing test rig and on-site tests in a steel company. And this study have made new diagnostic algorithm for the operating induction motors with the test results. These developments are including the use of monitoring and analysis of electric current to diagnose mechanical and electrical problems and gave the precise test results automatically.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권1호
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• pp.31-44
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• 2013

Recently, due to the high rise of energy costs and environmental problem issues, much attention has been paid to wood pellets. Wood pellets are produced by compressing woody biomass into cylindrical form. Wood pellets are suitable for use at various scales in industrial furnaces for heat production to replace conventional fossil fuel energy sources since the use of wood pellet that is carbon neutral can alleviate global warming. This study presents the result of developing two industrial wood pellet boilers with high safety having capacities of 290kW and 440kW. Efficiency has been improved by using a rotating screw bar grate burner. Special attention has been paid to the improvement of the safety of the wood pellet boilers from backfire by adopting a triple protecting system composed of a rotary feeder, an air curtain, and a backfire protecting DC-fan.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.511-516
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• 2005

This study is to investigate the pressure wave characteristics and the maximum pressure rise generated by instantaneous valve closure at the end of the straightening polybutylene double piping system with header. Experiments were conducted under the following conditions: initial pressure $1{\sim}5$ bar, flow velocity $0.5{\sim}3.0$ m/s and water temperature $25^{\circ}C$.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.163-170
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• 2008

Auxiliary port which had been known to be used to reduce the expansion loss of a refrigeration system was applied to a R134a reciprocating compressor in a household refrigerator cycle with an intention of improving the compressor performance. Effects of the auxiliary port on the compressor performance was investigated by a computer simulation program. When a simple hole was made on the side wall of the cylinder as an auxiliary port and surrounding gas inside the compressor shell was assumed to be drawn into the cylinder through the hole, maximum COP improvement of 1.66% was obtained. With auxiliary port equipped with a plate type of check valve, maximum COP was raised to be 1.99%. COP improvement was more distinctive with decreasing the discharge pressure; COP improvement was 5% with discharge pressure of 7 bar.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.235-240
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• 1997

The purpose of this experiment is to verify processing crack direction and state by the corrosion of electrifying re-bar in the salt water. The result of this experiment is the fact that the first crack appear on the surface of water-because of supplying of oxygen and water. The crack processing is on a surface to be contacted by air and to bottom as mainly the vertical direction from a surface of water. The crack by corrosion of steel reinforcing is emerged by the inside of concrete rather than surface concrete.

• Coupled systems mechanics
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• 제9권3호
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• pp.281-287
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• 2020

Nanotechnology is an upcoming technology that can provide solution for combating pollution by controlling shape and size of materials at the nanoscale. This review provides comprehensive information regarding the role of nanotechnology in pollution control at concrete structures. Titanium dioxide (TiO2) nanoparticles are a good item for concrete structures for diminishing the air polluting affect by gasses of exhaust. In this article, the mixture rule is presented for the effect of nanoparticles in environmental pollution reduction in concrete structures. The compressive strength, elastic modulus and reduction of steel bars in the concrete structures are studied. The Results show that TiO2 nanoparticles have significant effect on the reduction of environmental pollution and increase of stiffness in the concrete structures. In addition, the nanoparticles can reduce the use of steel bars in the concrete structure.

• 한국환경보건학회지
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• 제34권4호
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• pp.333-341
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• 2008

In this study, the possibility and the optimal conditions for treating slurry type piggery wastewater using supercritical water oxidation were tested in the laboratory. The results could be summarized as follows; The slurry type piggery wastewater, which was diluted 50 times, was treated most effectively at the pressure of 300 bar, the temperature of $550^{\circ}C$ and the residence time of 10 minutes. The air saturated water was injected, as an oxidizing agent, and the removal efficiencies of $COD_{Cr}$, T-N, $NH_4^+$-N and T-Pattheoptimal conditions were 92, 40, 59 and 100%, respectively. Therefore, analte rnativemea suremu stbetaken to improve theremo valefficiency of the nitrogen compounds.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2067-2073
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• 2018

This paper will present the design of a novel-type velocity-controllable electromagnetic coil launcher (EMCL). By studying the influence of initial capacitor voltage on the velocity of an EMCL, the launcher voltage can be set to precisely adjust the velocity of projectile launching. The simulation of voltage and velocity in relation to time is obtained by Maxwell software. The experimental data show that for the launch accuracy to be achievable, the actual precision is 2%. Because of the excellent performance of Velocity-controllable EMCL, it can replace the air gun and applied to split Hopkinson pressure bar (SHPB).

• 한국산학기술학회논문지
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• 제3권1호
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• pp.20-26
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• 2002

콘크리트의 품질관리에 활용하기 위하여 콘크리트의 시멘트-물비와 압축강도의 상관식을 시험을 통하여 구하였다. 그리고 콘크리트의 공기량, 슬림프 및 강도 시험결과를 데이터 베이스화 하고 X-R 관리도와 X-Rs 관리도를 작성하는 기능 그리고 사용재료에 대한 각종 시험결과를 정리할 수 있는 데이터 시트 기능을 가진 품질관리 프로그램을 개발하였다. 또한 이 프로그램 속에는 콘크리트 시험 비비기를 할 때의 배합계산 및 콘크리트 관련 용어사전 기능을 포함시켰다.

• 전기의세계
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• 제19권6호
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• pp.18-25
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• 1970

The object of this project is to manifest the mechanism of deterioration phenomena for dielectrics causing corona discharge and applies it for determine the standard corona detection technique. As the results, we observed that corona discharges may occur more strongly around cylindrical shape electrode in air than hemisphere shape electrode in vacuum, so that it depends on effects such as shape of the electrode, moisture, surface coditions, etc. According to observed the deterioration of dielectrics takes place in following stages. At first the attacked surface by an electron avalanche is uniformly eroded; then pits are formed; after that sharp channels are formed which lead to break-down as a treeing. The test are accelerated with higher frequencies by the cylindrical bar shape electrode in the pulse stright detection method more sensitive than Lissajous patterns. Lissajous patterns detection method is simple but usually insensitive and has disadvantage that the magnitude of the individual discharge is not measured.