• Korean Journal of Ichthyology
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• v.34 no.3
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• pp.218-222
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• 2022

Based on a single specimen (207.0 mm SL) collected from the southern coastal waters of Jejudo Island, morphological characteristics of Antennarius commerson were described as the first reliable record from Korea. The species is characterized by having a globose body covered with small bifurcated spinules, three dorsal spines including a naked illicium and attached pectoral lobe, 13 dorsal fin soft rays, 8 anal fin rays, and 11 pectoral fin rays. We adopted a tentative Korean name previously suggested, "Keun-ssin-being-i", for the species.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.2
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• pp.140-148
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• 2002

Anisotropic elastic constants of Zr-2.5Nb pressure tube materials were determined by a high temperature resonant ultrasound spectroscopy (RUS). The resonant frequencies were measured using alumina wave-guides and wide band ultrasonic transducers in a small furnace. The rectangular parallelepiped specimens were fabricated along with the axial, radial and circumferential direction of the pressure tube. A nine elastic stiffness tensor for orthotropic symmetry was determined in the range of room temperature ${\sim}500^{\circ}C$. As the temperature increases, the elastic constant tensor, cij gradually decreases. Higher elastic constants along the transverse direction compared to those along the axial or radial direction are similar to the case of Young's modulus or shear modulus. A crossing of shear elastic constants along axial direction and radial direction was observed near $150^{\circ}C$. This fact corresponds to the crossing of c44 and c66 of single crystal zirconium.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1079-1085
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• 2010

A steady-state analytical model was presented for a loop heat pipe (LHP) with an evaporator that has a flat geometry. On the basis of a series of reviews of the relevant literature, a sequence of calculations was proposed to predict the temperatures and pressures at each important part of the LHP: the evaporator, liquid reservoir (compensation chamber), liquid line, vapor line, and condenser. The analysis of the evaporator, which is the only part in the LHP that has a capillary structure, was emphasized. Thin-film theory is applied to account for the pressure and temperature in the region adjacent to the liquid-vapor interface in the evaporator. The present study introduced a unique method to estimate the liquid temperature at the interface. Relative freedom was assumed in the configuration of a condenser with a simplified liquid-vapor interface. Our steady-state model was validated by experimental results available in the literature. The relative error was within 3% on the absolute temperature scale, and reasonable agreement was obtained.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.748-749
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• 2008

대용량 전동기에는 역률보상용 콘덴서와 리액터를 설치하여 부하역률을 개선하고 있다. 역률보상용 콘덴서의 기동리액터 전.후단 설치지점에 따른 특성변화를 해석한 결과 콘덴서를 기동 리액터 전단에 설치한 경우 기동시의 순간적인 콘덴서 돌입전류로 상용주파수 부근의 고조파(1,3,5차) 공진이 발생하여 이로 인한 과전압이 콘덴서와 직렬리액터에 반복적으로 인가되어 수명이 단축됨을 확인할 수 있었다. 기동초기에 발생하는 과전압을 저감하기 위해서 콘덴서 회로의 연결점을 기동리액터 후단에 설치한 결과 인가전압과 전류가 감소됨을 알 수 있었다.

• Economic and Environmental Geology
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• v.10 no.4
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• pp.177-184
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• 1977

This study is focused on the geological structure of Igog-Jangam folded zone in the vicinity of Goesan town where Ogcheon group distributes. The geology is composed of Gyemyungsan formation, Daehyangsan quartzite, Munjuri formation and Hwanggangri formation of Ogcheon group unknown age in descending order, and porphyritic biotite granite and dyke rocks that intruded into the Ogcheon group. The study revealed that Igog-Jangam folded zone is a plunged synclinal fold based on the following evidences; 1) Some pebbles in Hwanggangri formation at Minaemi-gol (a name of village) consists of phyllite of Munjuri formation. 2) The pebble bearing phyllitic bed in this area, Hwanggangri formation was recognized as the uppermost member in Ogcheon group instead of the basal one of the group. 3) A crest of anticlinal fold has been appeared near the Goegang bridge as a structural counter-part of that of the present area. 4) The study of lineation of minor fold in Munjuri formation also suggests that Igog-Jangam folded zone manifests to be a synclinal structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.379-382
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• 2003

천공요소는 자동차의 배기 소음기, 공조기의 소음기 등을 포함하는 다양한 소음계에 널리 사용된다. 일반적으로 천공요소 들은 평균 유동과 소음원이 동시에 존재하는 환경에서 사용되며, 평균 유동 및 관 내부의 음압 레벨의 변화가 천공 부근에서의 임피던스에 큰 영향을 미치게 된다. 천공요소의 임피던스의 변화는 소음기의 음향학적 특성에 영향을 미치게 되므로, 유동이나 음압 조건이 임피던스에 미치는 영향에 대한 연구가 중요하다. 본 연구에서는 정밀 계측 및 전산유체역학적 모형을 이용해 천공요소의 임피던스에 영향을 미치는 주요 세 가지 인자 - 스치는 유동, 통과하는 유동, 음압 레벨 - 들을 고려하여 임피던스를 분석하고, 그 상관관계를 밝혔다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.6
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• pp.56-62
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• 1994

유동대전 현상을 밝히기 위해 간단한 유순환 장치에 설치된 프레스보드관(pressboard pipe)을 통하여 변압기 유를 순환시키면서 기초적인 실험을 행하였다. 특히, 측정 전극에 교류전계를 인가할 때 이것이 유동대전에 미치는 영향에 대하여 고찰하였다. 측정값은 절연유내에 분포된 전하의 분리와 완화에 기초를 둔 이론적 개념으로부터 유도된 공식에 의하여 검토되었다. 유동 대전은 외부에 교류전계를 인가하는 것에 의하여 증가하는 경향을 나타냈으며, 이는 교류전계의 전기력이 계면부근의 절연유내에 분포되어 있는 과잉전하에 영향을 준 결과로 나타난 현상임을 알 수 있었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.162-162
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• 2011

고강도 저가형 탄소 섬유 제작에 마이크로파 장비를 이용하는데 있어 공정 제어를 위한 온도 측정이 중요하다. 석영관 내부에 들어 있는 섬유의 표면 온도를 측정하기 어려우므로 직접 삽입한 K타입 열전대를 이용하여 입력 전력에 따른 섬유 다발 표면의 온도를 측정 하였다. 그 결과 안정화에 필요한 $300^{\circ}C$ 부근의 온도는 쉽게 얻을 수 있었으나 마이크로파가 방사되는 영역의 온도만 빠른 상승을 보여서 불균일도 해결을 위한 노력이 필요하다. 탄화 처리를 위한 고온 가열을 위해서 투입 전력을 648 W까지 증가시켰을 때 $727^{\circ}C$까지는 쉽게 상승하였으나 $2000^{\circ}C$ 이상을 획득하기 위해서는 고온 복사 손실을 줄 일 수 있는 전략이 필요하다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.942-944
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• 2005

In this study, eddy current signals from various anomalous defects in the heat exchanger tube are predicted af their signal slope characteristics no analyzed. The signal changes due to frequency increase are also observed. Based in the accumulated knowledge, the analysis of superimposed signal is attempted which includes the effects of support plate. Both differential and absolute bobbin probe signals are analyzed. For the prediction of signals, axisymmetric finite element modeling is used and this leads us to the utilization of slope angle analysis of the signal. Results show that differential signals are useful to locate the position of defect under the support plate and absolute signals no easy to predict and analyze even though they no superimposed signals. Combined use of these two types of signals will accomplish a reliable inspection.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.149-155
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• 2013

In this study, factors that affect the air entrainment within a closed conduit by air drawn in through an air vent are investigated using a hydraulic scale model, which represents a gated circular conduit system connected to the intake tower of an irrigation reservoir. In addition, using data obtained during the hydraulic experiments, experimental equations are developed to estimate the amount of air drawn in through the air vent. In case of pressurized flow conditions downstream of hydraulic jumps, the relationships between $\frac{Q_a}{Q_w}$ and $Fr_g-1$ of the data form a experimental equation, $\frac{Q_a}{Q_w}=0.0304(Fr_g-1)^{1.0622}$; in case of free surface flow conditions, $\frac{Q_a}{Q_w}=0.0271(Fr_g-1)^{1.8205}$. Comparing two data sets observed under the two flow regimes with the results of previous researchers, patterns of the data sets are similar to the results estimated using the equations presented previously, and this indicates that the quality of the data obtained during the hydraulic experiments is ensured. In addition, it is revealed that air entrainment phenomena in the regions close to air vents are affected by the characteristics of supercritical flows downstream of gates. Finally, it is concluded that the equation developed for pressurized flow conditions can be applied to design of air vents.