• Proceedings of the KIEE Conference
• /
• 2007.11b
• /
• pp.84-86
• /
• 2007

통신 및 디지털 연산 기술의 비약적인 발전은 변전소 내부의 정보를 공유 및 통합시켜 변전소 자동화 시스템을 등장할 수 있는 계기가 되었다. 그러나 변전소에 적용된 자동화 시스템은 152 종류의 서로 다른 프로토콜이 사용되어 IED(Intelligent Electronic Device)간 통신이 어려움에 직면하게 되었다. 따라서 이종 IED간 원활한 정보 공유가 가능하도록 변전소에 표준화된 통신 아키텍쳐로서 IEC 61850 통신 프로토콜이 규정되었다. 이 논문은 변전소 내부에 IEC 61850 통신 프로토콜을 이용한 IED간 통신 클라이언트 모듈을 개발한 사례를 소개하고자 한다.

• Applied Chemistry for Engineering
• /
• v.9 no.3
• /
• pp.372-376
• /
• 1998

Supported Pd($Pd/AlF_3$, $Pd/{\gamma}-Al_2O_3$) catalysts and solid-acid catalysts(${\gamma}-Al_2O_3$, ${\alpha}-Al_2O_3$, $AlF_3$) were used to perform dechlorination of HCFC-142b(1-chloro-1,1-difluoroethane) in the presence of excess hydrogen. In the reactions the effects of reaction temperature, the mole ratio(r) of $H_2$ to HCFC-142b and the amount of supported Pd on dechlorination of HCFC-142b into HFC-143a(1,1,1-trifluoroethane) or HFC-152a(1,1-difluoroethane) were investigated. The experimental results showed that the conversion of HCFC-142b to product gases were 60% and 92%, respectively, and the selectivity to HFC-143a in the product gases were 58% and 64% for $Pd/AlF_3$ and $Pd/{\gamma}-Al_2O_3$ catalysts, respectively. On these catalysts an optimum reaction condition was found at $200^{\circ}C$ with the space time of reactant gases as 1.05 second and the mole ratio of $H_2$ to HCFC-142b as 3. Solid-acid catalysts were also tested at the same reaction condition. The results showed that the conversions of HCFC-142b to product gases were 12%, 8% and 7%, and the selectivities to HFC-152a were 94%, 92% and 90% for ${\gamma}-Al_2O_3$, ${\alpha}-Al_2O_3$ and $AlF_3$ catalysts, respectively.

• Journal of the Korean Solar Energy Society
• /
• v.31 no.6
• /
• pp.49-56
• /
• 2011

In this study a novel cogeneration system driven by low-temperature sources at a temperature level below $190^{\circ}C$ is investigated by first and second laws of thermodynamics. The system consists of Organic Rankine Cycle(ORC) and an additional heat generation as a parallel circuit. Seven working fluids of R143a, R22, R134a, R152a, $iC_4H_{10}$(isobutane), $C_4H_{10}$(butane), and R123a are considered in this work. Maximum mass flow rate of a working fluid relative to that of the source fluid and optimum turbine inlet pressure are considered to extract maximum power from the source. Results show that due to a combined heat and power generation, both the efficiencies by first and second laws can be significantly increased in comparison to a power generation, however, the second law efficiency is more resonable in the investigation of cogeneration systems. Results also show that the working fluid for the maximum system efficiency depends on the source temperature.

• Proceedings of the Technology Innovation Conference
• /
• 2004.02a
• /
• pp.152-166
• /
• 2004

The importance of maritime sector in Korea has been increasingly recognized in recent days. As the country enters the $\ulcorner$new ocean era$\lrcorner$, the oceans are often regarded as holding the keys to solve the problems of modern industry associated with changing environment as well as changing societies and national politics. This paper attempts to address the national maritime R&D policies and their relative importances. In the methodology, Saaty's analytic hierarchy process model is used to evaluate and rank the selected maritime R&D projects which have a wide range of characteristics and policy implications. The criteria used for policy evaluation relates specifically to the Korea's evaluation needs and culture, and those criteria are weighted according to their relative importance as perceived by the maritime R&D specialists.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.21 no.2
• /
• pp.109-117
• /
• 2009

In this study, thermodynamic performance of R430A is examined both numerically and experimentally in an effort to replace HFC134a used in the refrigeration system of domestic water purifiers. Even though HFC134a is used predominantly in such a system these days, it needs to be phased out in the near future in Europe and most of the developed countries due to its high global warming potential. To solve this problem, cycle simulation and experimental measurements are carried out with a new refrigerant mixture of 76%R152a124% R600a using actual domestic water purifiers. This mixture is numbered and listed as R430A by ASHRAE recently. Test results show that the system performance with R430A is greatly influenced by the amount of charge due to the small internal volume of the refrigeration system of the domestic water purifiers. With the optimum amount of charge of 21 to 22 grams, about 50% of HFC134a, the energy consumption of R430A is 13.4% lower than that of HFC 134a. The compressor dome and discharge temperatures and condenser center temperature of R430A are very similar to those of HFC134a at the optimum charge. Overall, R430A, a new long term environmentally safe refrigerant, is a good alternative for HFC134a requiring little change in the refrigeration system of the domestic water purifiers.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.11 no.4
• /
• pp.152-157
• /
• 2006

Samples of Meretrix lusoria were collected monthly from the tidal flat of Simpo, Puan-gun, Chollabuk-do, west coast of Korea from April 2004 to March 2005. Age of M. lusoria was determined from the rings on the shell. The relationship between shell length and ring radius in each ring group was expressed as a regression line. Therefore, there is a correspondence in each ring formation. Based on the monthly variations in the marginal index (MI') of the shell, it is assumed that the ring of this species was formed once a year during the period of February to April. The relationship between shell length (SL) and shell height (SH; mm) was highly correlated with shell height as the following equation: SH = 0.8103 SL + 0.5145 $(r^2=0.991)$. The shell length (SL) - shell width (SW) relation was also expressed by the following equation: SW = 0.4897 SL + 0.0315 $(r^2=0.976)$. Shell length (SL; mm) and total weight (TW; g) was expressed by the following equation: $TW=2.9195\times10^{-4}\;SL^{2.9547}\;(R^2=0.991)$. Shell length (SL) and shell height (SH; mm) was highly correlated with shell height as the following equation: $SH=0.8103\;SL+0.5145\;(R^2=0.991)$ The shell length (SL) - shell width (SW) relation was also expressed by the following equation: $SW=0.4897\;SL+0.0315\;(R^2=0.976)$. Growth curves for shell length and total weight fitted to the von Bertalanffy's growth curve were expressed respectively as: $SL_t=104.9[l-e^{-0.2235(t+0.7677)}],\;TW_t=280.8[l-e^{-0.2235(t+0.7677)}]^{2.9547}$.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.4 no.2
• /
• pp.152-161
• /
• 2009

Insider threat is becoming a very serious issue in most organizations and management is responsible for security implementation. This study is to develop a personnel security management indicators in the areas of Personnel Assurance, Personnel Competence, and Security Environment and protection against insider threats. In this study, the information security management system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.5
• /
• pp.403-410
• /
• 2007

In this study, natural refrigerants and their mixtures that can supplement and replace R12 and R134a in automobile air-conditioners are studied. R134a is currently used as the refrigerant in new motor vehicle air conditioners, replacing the ozone depleting refrigerant R12. Although R134a has no ozone depletion potential, it has a relatively large global warming potential, approximately 1300 times that of $CO_2$ over a 100 year time horizon. For this reason, performance of natural refrigerants and their mixtures containing R152a, RE170 (Dimethylether, DME) and R600a (Isobutane) are measured under 2 different temperature conditions. They were tested in a refrigerating bench tester with an open type compressor. The test bench provided about 4 kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. Test results show that the coefficient of performance (COP) of these refrigerants is up to 21.55% higher than that of R12 in all temperature conditions. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for automobile air-conditioners.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.151-152
• /
• 2000

For excimer laser crystallization (ELC), energy density, number of pulses, beam uniformity, and condition of initial amorphous Si (a-Si) films are significant factors contributing the final microstructure and the performance of low-temperature polycrystalline Si TFTs. The process and equipment have been achieved a significant improvement, but still, environmental factors associated with initial amorphous Si (a-Si) films and process conditions need to be optimized.

• Journal of Korean Academic Society of Home Health Care Nursing
• /
• v.26 no.1
• /
• pp.64-71
• /
• 2019

Purpose: This study investigated the factors affecting spirituality in nursing students. Method: A total of 152 nursing students participated in the study. Data collection was conducted from October to November 2018. The data were analyzed using descriptive statistics, t-tests, analysis of variance, Pearson's correlation coefficient, and multiple stepwise regression via SPSS WIN 25.0. Results: The mean scores for empathy, gratitude, positive affect, negative affect, and spirituality were all average. However, there were significant differences in mean scores for spirituality according to satisfaction with major (F=5.88, p=.003), study grade (F=10.17, p<.001). Spirituality was found to be correlated with fantasy (r=.17, p<.001), empathic concern (r=.41, p<.001), perspective taking (r=.42, p<.001), personal distress (r=-.31, p<.001), gratitude (r=.65, p<.001), positive affect (r=.52, p<.001), and negative affect (r=-.30, p<.001). Significant predictors of spirituality included gratitude (${\beta}=.38$, p<.001), study grade (${\beta}=.34$, p=.009), positive affect (${\beta}=.29$, p<.001), and perspective taking (${\beta}=.16$, p=0.37), one of the sub-dimensions of empathy. Conclusion: To improve spirituality among nursing students, nursing educators should develop educational intervention programs to promote gratitude, study grades, positive affect, and perspective taking.