• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.644-648
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• 2004

In the present study were examined numerically and experimentally the off-design performance characteristics on an axisymmetric plug nozzle with variable throat area. In this nozzle concept, its throat area can be changed by translating the plug into the axial direction. First, a mixed-expansion plug nozzle, in which two expansion parts are arranged both inside and outside, was designed by means of the method of characteristics. Second, the CFD analysis was verified by the cold-flow wind tunnel test. Third, its performance characteristics were evaluated over a wide range of pressure ratio from half to double throat area through the design point, using the CFD code verified by the wind tunnel tests. It was made clear from the study that not so critical thrust efficiency losses were found and the maximum thrust efficiency loss was at most approximately 5 % under off-design conditions without external flow. This result shows that a plug nozzle can give the altitude compensation even under off-design geometry operations. However, shock waves were observed in the inner expansion part under the doubled throat area operation and thus some thermal problems may be caused on the plug surface. Furthermore, collapse of cell structure on the plug surface was observed with external flow (around Mach number 2.0) as it became lower pressure ratio below the design point and the fact may result in big efficiency loss regardless of geometrical configuration.

• Animal Systematics, Evolution and Diversity
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• 제36권2호
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• pp.167-174
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• 2020

A halacarid species of the genus Copidognathus is newly reported from Korea: C. daguilarensis Bartsch, 1997, which was described from Hong Kong. It is redescribed herein with detailed illustrations. Korean specimens coincide well with the original description, however, they showed two minor morphological discrepancies from it: quite shorter second palpal segment than the fourth and a modified dorsal seta on the second palpal segment. Korean specimens were rather smaller than the type specimens from Hong Kong, however, they did not show significant differences in the length to width ratios of important body parts. The number of perigenital setae was more variable in the Korean males, ranged 24-29 setae, versus 25-26 in Hong Kong's. Copidognathus daguilarensis is reported for the first time outside the type locality, and joins as the second member of the gibbus group in the northwest Pacific.

• 대한설비공학회지:설비저널
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• 제35권12호
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• pp.41-48
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• 2006

For the Designing a Dedicated Outdoor Air System with Ceiling Radiant Cooling Panels the concept of a dedicated outdoor air system(DOAS) with parallel sensible cooling was born from the decoupled system concept, which can be summarized as decoupling of ventilation and air-conditioning functions, or decoupling of sensible and latent load functions. First , remove the latent loads from the outside air(OA) intake and generated in spaces using a 100% OA ventilation system(i.e., DOAS). Second, remove the space sensible loads using a parallel mechanical cooling system, such as fan coil units, conventional variable air volume , and ceiling radiant cooling panel(CRCP) independent of the ventilation system.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.379-383
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• 2020

The novel voltammetry using a semi-circular potential wave for quasi-reversible charge transfer system on electrode is theoretically investigated. Compared with conventional voltammetry based on linear sweep such as linear sweep voltammetry (LSV), semi-circular potential sweep voltammetry (SCV) may decrease the charging current outside the center of potential range and increase the faradaic current at the midpoint due to variable scan rate. In this paper, we investigate the system based on macroelectrode where simple 1 dimensional (1 D) diffusion system is valid with various charge transfer rate constant (k₀). In order to observe the amplification at midpoint, voltammetric response with different midpoint ranging from -200 mV to 200 mV are studied. SCVs shows both the shift of peak potential and the amplification of peak current for quasi-reversible electrode reaction while only higher peak current is observed for reversible reaction. Moreover, the higher current at midpoint enable the amplification of current at low overpotential region which may assist the determination of onset potential as a figure-of-merit in electrocatalyst.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1063-1064
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• 2008

Bimodal tram has a carbody made of polymer composite material which is good electrical insulator. As an series hybrid type, Alternating voltage generated from generator coupled with CNG engine are rectified and transformed to variable voltage ranges which are applied to electrical apparatus and ECUs equipped inside of the tram. The failures of electrical insulation between high voltage($400V{\sim}800V$) and low voltage(24V) or between different kind of voltages such as AC and DC may cause some electrical interferences to prevent from operating rightly and other safety problem. This paper have investigated about the degradation factors of the electrical insulation and the earthing method available to bimodal tram, which is effective for preventing the electromagnetic interference coming from the inside or outside of tram but need some detecting measurements of earth leakage through electrical systems.

• 대한기계학회논문집
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• 제19권7호
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• pp.1657-1664
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• 1995

For dynamic analysis of flexible structures, classical linear modeling has been widely used due to its several good aspects. However, it was found that the modeling often lost its accuracy. So, it is important to know the valid range of the modeling before it is used. more complicated modelings are needed to obtain reliable results only outside the valid range of the classical linear modeling. In this study, some rigid body motions of flexible structures which lead to the failure of the classical linear modeling are investigated. Hybrid deformation variable modeling, which is proved to be accurate in previous studies, is used to figure out the valid range of the classical linear modeling through numerical examples.

• 대한기계학회논문집A
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• 제32권12호
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• pp.1146-1152
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• 2008

In the initial stage of guided missile launching, the dynamic stability of a missile is highly influenced by disturbances from the outside and interferences among the launching system parts. This research develops a program for guided missile launching system analysis. Random variables are used to analyze quantitatively the missile characteristic response. An example of results with the program applied into a specific System is presented to demonstrate the effectiveness of the propose method.

• 아동학회지
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• 제21권2호
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• pp.119-133
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• 2000

This research examined factors that differentiate the child-rearing practices of 495 Japanese fathers living in Tokyo and 526 Korean fathers living in Seoul. All subjects were fathers of school-age children, Findings were that the sense of devotion/reward in life is the decisive variable behind affection in the child-rearing practices of fathers of both nations, In the Japanese sample, the less they felt financial burdens and psychological constraints, the more affection shown in their child-rearing practices. In the Korean sample, more affection was noted among fathers whose primary views on child-rearing were centered on the continuity of the family line. Such socio-demographic variables as fathers working long hours and/or mothers working outside the home had a negligible influence of affection driven child-rearing practices of both groups.

• 아동학회지
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• 제27권3호
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• pp.301-317
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• 2006

This study investigated parenting stress and requests for parent education by fathers with infants and preschool children. Subjects were 220 fathers. Data were analyzed by factor analysis and ANOVA. Results showed that middle class fathers whose wife had a job outside the home experienced more stress. Sex of child was a significant variable. : fathers with daughters expressed more requests for a father education program for a father education program, from highest to lowest, were for methods of childcare, the development of a child, guidance for discipline in daily life, relationship with their partner, and the fathers' role.

• Animal Systematics, Evolution and Diversity
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• 제18권1호
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• pp.23-33
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• 2002

살갗살이과(Lichomolgidae)에 속하며 원기재 이후 그 기록이 매우 드물었던 요각류 2종 Lichomolgus inflatus Tanaka와 Philoconcha paphiae Yamaguti가 남해도에서 떡조개 (Dosinorbis japonicus)로부터 발견되어 재기재하였다. Lichomolgus inflatus는 L. chamarum Humes와 매우 유사하나 이마돌기와 생식이중절의 특징으로 서로를 구별할 수 있다. Philoconcha paphiae는 매우 변이가 심한 다리 강모식을 가지는 것이 발견되었다. 이 두 종에 대한 본 기록은 일본 외의 지역에서는 처음이다.