• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.99-101
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• 2005

This paper presents an adaptive overcurrent relay applied to interconnecting wind generators in distribution networks. When a fault occurs in the case of the decreasing the wind power generator output, the conventional overcurrent relay can't detect the fault. The suggested adaptive overcurrent relay can detect. An adaptive overcurrent relay improves reliability and security of the power system protection with distributed generator APSCAD/EMTDC simulation results have shown effectiveness of the proposed method.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.530-537
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• 2020

This study investigates the effect of an included angle and heat flux on heat transfer of V-shape tube array having a horizontal upper tube. The test uses two stainless steel tubes with a smooth surface submerged under the water at atmospheric pressure. The angle varies from 2° to 24°. The heat transfer coefficient gets decreasing in consequence as the angle increases. The enhancement due to the lower tube is distinct as the heat flux is lower than 60 kW/㎡, where the effect of the convective flow is dominant. The present study and the published results show a similar tendency. Although the heat transfer coefficient for the present study is smaller than the symmetry case, enhanced heat transfer is observed compared to the tube array having a lower horizontal tube as the included angle is less than 10°.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.599-602
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• 2005

In this research, the characteristics of the strength development and chloride attack resistance on the concrete using high early strength cement by steam curing temperature condition were studied. As a result, It is observed that the early strength(16hr) is increasing and the strength of 28 days is decreasing, according as the rising of the steam curing temperature without the kinds of base cement(OPC and high early strength cement). On the other hand, it is observed that the more the contents of the unit binder(base cement + GGBF) is abundant, the more the steam curing temperature can be reduced in case of the high early strength. Also, the chloride attack resistance is improved according as the amount of GGBF is increased with the kinds of base cement(OPC and high early strength cement).

• KIEAE Journal
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• 제9권2호
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• pp.53-58
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• 2009

There are increasing developments and uses of functional building materials are recently developed and introduced to the test method for the materials. Especially, moisture problem has a major role are also being established in indoor air quality problems. The purpose of this study is to evaluate the water vapour adsorption/desorption property of a ceiling material. The variation of the temperature and moisture were measured with the application materials by mock up test based on JIS 1470-1. The result shows that water vapour adsorption/desorption property of ceiling material is appeared in changes of moisture adsorption and desorption in comparison with that of a general ceiling material. Therefore, in case of decreasing and increasing in humidity, these materials can be used as an finishing material to sustain comfort condition.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.247-249
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• 2011

Pre-foaming, one of the manufacturing way of foamed concrete, is influenced by foaming agent. When the foaming agent diluted with water, surface tension and viscosity are varied. Therefore, this study is reviewing the surface tension, viscosity and unit weight of foam by experimental factor such as foaming agent types(AES, AOS, VS FP) and foam agent dilution concentration (1, 3, 5%) and temperature of materials (5, 10, 20℃). As an expeimental result, the surface tension and viscosity slightly increased with increasing concentrations. Meanwhile, when increasing temperature, the viscosity has decreased. FP produce relatively stable foams only in case 3% or more, which produce unstable foams containing large amount of water content by decreasing only insignificant surface tension when diluted at concentration of 1%.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.125-126
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• 2011

Construction projects are being more complicated in proportion to the economic development. Process management is a critical issue in the construction that decides success of a project. Especially, a TACT method which divides and manages resources to repeat each activity is more important. Although becoming an issue dealing with the delay at winter season, it is not property developed. This paper suggests 'activity priority method' and 'TACT unit method' through case study. We validate necessity and efficiency of the TACT method through simulations and a survey. We expect cost reduction by decreasing unnecessary spending.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2674-2677
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• 1999

Resonant converters have several salient features such as high efficiency and low noise. Therefore, ZVS-PWM controlled series resonant converter with active-clamp technique is presented. The combination of an active-clamp technique and resonant circuit makes it possible to control the output voltage of the resonant converter with PWM. This new resonant converter was implemented and has achieved a good controllability. In this paper, the normal load characteristics and abnormal voltage increase in the case of the light load are analyzed. As a result, it is clarified that the stray capacitance of the transformer is a cause of the abnormal voltage increase. Then, it is confirmed that the abnormal voltage increase is suppressed by decreasing the duty ratio. ZVS condition is analyzed. The maximum efficiency of 89% is obtained for the output of 10V and 5A.

• 한국환경과학회지
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• 제26권2호
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• pp.265-268
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• 2017

The objective of this study was to evaluate the characteristics of duck litter in ducks fed diets containing Houttuynia cordata powder. One-day-old ducklings (Pekin) were randomly divided into two groups and fed a control or 1% H. cordata powder-containing diet for an experimental period of three weeks. The results showed that pH for 1-2 weeks and total nitrogen for 1-3 weeks in duck litter were affected by dietary treatments with 1% H. cordata powder (P < 0.05). For Volatile Fatty Acids (VFAs), there was no significant difference (P > 0.05) between ducks fed 1% H. cordata and control diets, as shown in the results for acetic acid and propionic acid in duck litter over three weeks; but, this was not the case for propionic acid at 3 weeks. The inclusion of 1% H. cordata powder in the diet had a the positive effect on increasing the total nitrogen and decreasing pH and VFAs in duck litter.

• 수산경영론집
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• 제28권1호
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• pp.71-83
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• 1997

This paper tries to suggest one kind of estimation method of compensation for restriction in licenced fisheries caused by a large scale coastal reclamation under Code 62 of the Fisheries Act. To do so, the paper focuses on estimating the restriction rate of licenced fisheries through introducing several new factors for calculating the amount value of compensation, such as the restriction rate of fishing area, the decreasing rate of fishing time and the variation rate of fishing cost. Finally, the paper tries to apply the method to the case of compensation fer fisheries damage at the Incheon coastal area caused by the construction of the base of LNG of 1992.

• 치과방사선
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• 제5권1호
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• pp.33-37
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• 1975

The author has observed 64 films from M. P. D. syndrome cases taken in Dept. of Radiology, the Infirmary of Dental College, Seoul National University in 1974, and obtained the following results: 1. In M. P. D. syndrome, the ratio between the female and the male were 2:l. 2. The prevalenting age were aged 20, 30, 10, and 40 in decreasing order. 3. The incidence was 21.8% in the left side, 29% in the right, and 21% was bilaterally, which show the right most frequent. 4. The roentgenograms revealed variable findings in each case, but there were not recognized any significant differences.