• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1094-1097
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• 1999

This paper presents a new PID control scheme based on the feedback of averaged derivatives to realize a noise-free differential control. The PID(Proportional, Integral and Differential) control is still one of the control methods in most wide use. In the paper, the conventional PID control adopting filtering technique is analyzed with new interpretation of filtering function. In order to overcome the drawbacks of the conventional PID control, this paper introduces the feedback of averaged derivatives in the noisy environment, and suggests a new PID control scheme using delay components to realize a noise-free differential control. The proposed PID control yields good performance much similar to the original system response in case of no noises. The proposed control scheme has been tested for the load frequency control of power systems.

• 대한기계학회논문집A
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• 제20권10호
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• pp.3160-3172
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• 1996

A search algorithm for the collision free, time optimal transport path of overhead cranes has been proposed in this paper. The map for the working environment of overhead cranes was constructed in the form of three dimensional grid. The obstacle occupied region and unoccupied region of the map has been represented using the octree model. The best-first search method with a suitable estimation function was applied to select the knot points on the collision free transport path to the octree model. The optimization technique, minimizing the travel time required for transporting objects to the goal while subjected to the dynamic constraints of the crane system, was developed to find the smooth time optimal path in the form of cubic spline functions which interpolate the selected knot points. Several simulation results showed that the selected estimation function worked effectively insearching the knot points on the collision free transport path and that the resulting transport path was time optimal path while satisfying the dynamic constraints of the crane system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.519-522
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• 1997

In this study, the collision free path planning method of the articulated manipulator using sequential search is proposed. This method is to find the joint path of the manipulator with many degrees of freedom from the distal joint to the proximal one. To do this, the initial work space of the gantry manipulator, which is a remote maintenance equipment of the radioactive environment, is defined from the condition that the distal joint configuration is determined by the posture of maintenance. Then, 2-dimensional configuration space with the obstacle area is represented and the collision free path of manipulator is searched in the configuration space. And, this method is verified using the graphic simulation in virtual workcell for the spent fuel disassembling processes. The result of this study can be effectively used in implementing the maintenance processes for the hot cell equipment and enhance the reliability of the spent fuel management.

• 한국환경교육학회지:환경교육
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• 제22권4호
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• pp.53-65
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• 2009

Saemangeum is the largest reclaimed land in Korea. Saemangeum is the large scale project responding to the economic demand of globalization, and a government initiated new development business with a vision of global Free Economic Zone(FEZ). Jeollabuk-province conducted a international competition to establish a global-scale, creative development plan and grow the Saemangeum as an international destination of economy, and a world-wide brand. SGFEZ has much to offer in terms of tourists attractions and breathtaking scenery. And tourism is one of the important industry in SGFEZ. Many tourist facilities will be construct in SGFEZ. Environment is the important issue in many field of study. Recent days, green growth come into the spotlight in Korea. But even as SGFEZ prepares for its future global tourists attraction, so much of the tourism policy directions remains unconsidered. The objective of this study was to suggest tourism policy direction, especially concentrated on ecology tourism policy direction of Saemangeum Gunsan Free Economic Zone(SGFEZ).

• Nuclear Engineering and Technology
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• 제3권1호
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• pp.21-31
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• 1971

금속의 소성변형에 필요한 일의 일부는 전표면자유에너지 (Total Surface Free Energy)의 변화에 소모된다. 전표면자유에너지 변화는 비표면 자유에너지 (Specific Surface Free Energy)에 의해 변화하며 비표면자유에너지는 분위기에 따라 달라 진다. 열역학적규명, 체적불변율과 흡착으로 인한 두 개의 판이하게 다른 강화 혹은 약화를 초래하는 전위(Dislocation) 상호작용기구를 기반으로 금속의 소성변형으로 인한 가공경화, 응력 및 에너지에 미치는 분위기의 영향을 이론식으로 도출했다. 이론식은 진공중금속표면장력 (${\gamma}$$_{s}$), 개면장력 (${\gamma}$$_{se}$ ), 포면전위밀도($\rho$$_{s}$), 내부전위 밀도($\rho$$_{i}$)와 표면노출율(f)의 함수로 표시할 수 있었다. 이론식을 이용하여 각기 다른 분위기내에서의 금속의 기계특성을 예측 비교해봤다.다.다.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.244-248
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• 2018

We propose a method for improving the reliability of a solar cell by applying a fluorinated surface coating to protect the cell from the outdoor environment using an atmospheric pressure plasma (APP) treatment. An APP source is operated by radio frequency (RF) power, Ar gas, and $O_2gas$. APP treatment can remove organic contaminants from the surface and improve other surface properties such as the surface free energy. We determined the optimal APP parameters to maximize the surface free energy by using the dyne pen test. Then we used the scratch test in order to confirm the correlation between the APP parameters and the surface properties by measuring the surface free energy and adhesive characteristics of the coating. Consequently, an increase in the surface free energy of the cover glass caused an improvement in the adhesion between the coating layer and the cover glass. After treatment, adhesion between the coating and cover glass was improved by 35%.

• 대한금속재료학회지
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• 제46권2호
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• pp.80-87
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• 2008

Many researches related to the reliability of Pb-free solder joints with PCB (printed circuit board) surface finish under thermal or vibration stresses are in progress, because the electronics is operating in hash environment. Therefore, it is necessary to assess Pb-free solder joints life with PCB surface finish under thermal and mechanical stresses. We have investigated 4-points bending fatigue lifetime of Pb-free solder joints with OSP (organic solderability preservative) and ENIG (electroless nickel and immersion gold) surface finish. To predict the bending fatigue life of Sn-3.0Ag-0.5Cu solder joints, we use the test coupons mounted 192 BGA (ball grid array) package to be added the thermal stress by conducting thermal shock test, 500, 1,000, 1,500 and 2,000 cycles, respectively. An 4-point bending test is performed in force controlling mode. It is considered that as a failure when the resistance of daisy-chain circuit of test coupons reaches more than $1,000{\Omega}$. Finally, we obtained the solder joints fatigue life with OSP and ENIG surface finish using by Weibull probability distribution.

• 자동차안전학회지
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• 제14권2호
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• pp.90-95
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• 2022

Composite material is widely used in the automotive industries because it has excellent mechanical properties and is possible to reduce weight due to the low density. However, there is a new obstacle to meet environment regulation like Cu less or Cu free regulation for the friction material. Although it is strongly demanded, there are few research results about that unfortunately. Unless this problem is not solved properly, it is impossible to apply composite brake system to vehicle. In this paper, a new eco-friendly friction material for composite brake system is represented to respond these regulations. To do this, friction characteristics between existing low steel friction material and new eco-friendly friction material are verified to secure performances for brake system such as effect characteristic, fade characteristic and wear characteristic. And composite brake gets the equivalent or better performance compared to a low steel friction material. Finally, this result contributes to the study of major principles for the development of eco-friendly friction material in the future.

• Journal of Platform Technology
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• 제10권4호
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• pp.70-81
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• 2022

본 논문에서는 클라우드 자원의 무중단 수직 확장 서비스 제공을 위한 VMP(Virtual Machine Placement) 방안을 제시하였다. 수직확장을 위해서는 물리 서버의 여유 공간을 사전에 확보해야 하기 때문에, 이를 위한 FirstFit 배치 전략 기반의 가상 서버 할당율을 가변적으로 조정하는 "일반-혼합-수직의 모드 전환" 알고리즘을 제시하였으며, 수직 확장 비율, 가상화율, 여유자원율 등을 파라미터로 하여 시뮬레이션을 수행하였다. 시뮬레이션 결과, 수직 확장 비율이 50% 일 경우에 여유 공간을 고려하면 전체적으로 150%의 자원의 필요하나, 제안한 알고리즘의 시뮬레이션 결과로는 최대 125%의 여유 공간만을 필요로 하는 것으로 나타났다.

• 한국환경보건학회지
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• 제41권2호
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• pp.126-132
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• 2015

Objectives: The Korean government implemented a smoke-free regulation for pubs with a net indoor area of ${\geq}100m^2$ on January 1, 2014. The purpose of this study was to determine the indoor levels of concentrations of particulate matter smaller than $2.5{\mu}m$ ($PM_{2.5}$) in implemented and non-implemented pubs in Seoul and Changwon. Methods: $PM_{2.5}$ concentrations in fifty-two $100-150m^2$ (implemented) and fifty-seven < $100m^2$ (non-implemented) pubs were measured. A real-time aerosol monitor was used to measure $PM_{2.5}$ concentrations. Field technicians recorded characteristics of the pubs including net indoor area, indoor volume and presence of smoking rooms and counted the number of burning cigarettes, patrons and vents. Results: Differences between indoor and outdoor $PM_{2.5}$ concentrations in $100-150m^2$ and < $100m^2$ pubs were not significantly different in each city. Smoking was observed in 33% of $100-150m^2$ pubs and 51% of < $100m^2$ pubs. Average differences between indoor and outdoor $PM_{2.5}$ concentrations in the $100-150m^2$ and < $100m^2$ pubs were $79.2{\mu}g/m^3$ and $155.6{\mu}g/m^3$, respectively. When smokers were not observed, differences between indoor and outdoor $PM_{2.5}$ concentrations ware $12.4{\mu}g/m^3$ in $100-150m^2$ pubs and $24.5{\mu}g/m^3$ in < $100m^2$ pubs. Conclusion: Although the regulation was implemented only in ${\geq}100m^2$ pubs, a higher difference between indoor and outdoor $PM_{2.5}$ concentrations was observed in implemented and non-implemented pubs with smokers. Strict implementation of the regulation in all pubs is needed for better indoor air quality.