• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.220-226
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• 2002

A general solution method is presented to obtain the unbalance response orbit from the finite element based equations of motion of a gear-coupled two-shaft rotor-bearing system. Particularly, are proposed the analytical solutions of major and minor axis radii of the orbit. The method has been applied to analyze the unbalance response of a 800 refrigeration-ton turbo-chiller rotor-bearing system, having a bull-pinion speed increasing gear. The bumps of unbalance responses have been observed at the first torsional natural frequency due to the coupling of lateral and torsional dynamics by the gear meshing. Further, the proposed analytical solutions have been validated with results obtained by a full numerical approach.

• Laser Solutions
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• v.2 no.2
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• pp.42-51
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• 1999

This study has been performed to investigate into some effects of the output power and traverse speed of laser beam on the microstructures, hardness and fatigue resistance of the ductile iron surface-hardened by $CO_2$ laser defocussed beam. Optical micrographs have shown that with increasing the output power and decreasing the traverse speed, the martensite was coarsened and some retained austenite were appeared in ductile iron. The microstructures of hardening zone were composed of bull's eye and some nodular graphite dissolved structures by the effect of self quenching. Fatigue fracture characteristics of ductile iron have appeared in the high stress and low stress ranges. The fracture initiated at nodular graphites in the surface hardened layer due to the stress concentration caused by a notch effect. The interior graphite nodules were broken away or popped out during crack propagation. Fatigue test has shown that values of fatigue strength considerably increased with increasing output power at a given traverse speed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.121-124
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• 2006

본 논문에서는 영상 압축에 있어서 사용되는 새로운 고속 움직임 추정 기법에 대해 소개한다. 전역 탐색 블록 정합 알고리즘(FSBMA)은 최상의 PSNR을 갖는 화질로 움직임 벡터를 추정할 수 있지만 높은 계산량으로 인하여 실시간 구현에 부적합하다는 단점을 가지고 있다. 그러므로 계산량을 낮추면서 유사한 화질을 유지할 수 있는 많은 고속 탐색 기법들이 제안되어 왔다. 본 논문에서는 기존의 잘 알려진 고속 블록 정합 알고리즘을 수정 보완한 새로운 알고리즘을 제안한다. 제안한 방법에서는 움직임 추정에서의 고속 블록 정합 알고리즘에 있어 변형된 다이아몬드(Diamond) 탐색 기법을 이용하여 영상이 갖는 서로 다른 움직임 패턴에 대해 움직임의 방향성에 따라 적응적으로 탐색 방향과 패턴을 달리하면서 움직임을 예측하여 다이아몬드(Diamond)탐색 알고리즘과 유사한 화질을 유지하면서 보다 적은 계산량을 가지고 움직임 벡터를 추정학 수 있다. 또한 이를 PMVFAST(Predictive Motion Vector Field Adaptive Search Technique)와 결합함으로서 보다 좋은 화질을 가질 수 있다.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3201-3211
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• 2010

Previous work on the phase-shifted version of the multichannel quantum-defect theory (MQDT) for a system involving 2 closed and many open channels (Lee, C.-W. Bull. Korean Chem. Soc. 2010, 31, 1669) was extended to obtain the formulae of the spectral shape parameters with the structure of a pole extracted explicitly for general cases only limited by 2 non-degenerate closed channels. The theory was applied to the narrow $6p_{1/2,3/2}np$ J = 1 autoionizing Rydberg series in barium perturbed by the $6p_{3/2}nf$ states obtained by de Graaff et al.

• Kyungpook Mathematical Journal
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• v.58 no.3
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• pp.519-531
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• 2018

In this paper, we investigate the uniqueness problem of entire functions sharing two polynomials with their k-th derivatives. We look into the conjecture given by $L{\ddot{u}}$, Li and Yang [Bull. Korean Math. Soc., 51(2014), 1281-1289] for the case $F=f^nP(f)$, where f is a transcendental entire function and $P(z)=a_mz^m+a_{m-1}z^{m-1}+{\ldots}+a_1z+a_0({\not{\equiv}}0)$, m is a nonnegative integer, $a_m,a_{m-1},{\ldots},a_1,a_0$ are complex constants and obtain a result which improves and generalizes many previous results. We also provide some examples to show that the conditions taken in our result are best possible.

• Korean Journal of Agricultural Science
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• v.28 no.1
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• pp.59-64
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• 2001

This study is on the method of direct transaction with farmers, a farmers' group and consumers through internet. Approximately the method in this study could be divided into 4 sections: 1) full information display about agricultural products of farmers, farmers' group, 2) consumers' choice about the best stuff, 3) direct transaction system by using tele-banking and 4) a delivery system in conveying method or an interview type electronic commerce system that carry out the direct visit These methods are to make the merits of the existing traditional type commerce system's to be maximized to make bull use of electronic commerce system.

• The Korean Journal of Mycology
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• v.1 no.1
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• pp.35-43
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• 1973

저자(著者)는 우리나라산(産) 균심류의 정체(正體)를 구명(究明)하고자 1946년(年)부터 금일(今日)에 이르는 동안 서울시내(市內), 광릉(光陵), 수원(水原), 양양(襄陽), 속초(束草), 설악산(雪嶽山), 목포(木浦), 나주(羅州), 울산반도등지(蔚山半島等地)의 산야(山野) 인가(人家) 노변(路邊)에서 야생균심(野生)을 채집정리(採集整理)하여 기(旣)히 조사발표(調査發表)된 종(種)을 종합(綜合)하여 2문(門), 2강(綱), 3목(目), 12아목(亞目), 22과(科)7아과(亞料), 274종(種)을 보고(報告)하는 바이다. 저자(著者)가 금일(今日)까지 미기록종(未記錄種)으로 사정(査定)한 종(種)은 하기(下記)와 같다. 1. Polysticus flabelliformis (Klotzsch.) Cke. 2. Thelephora palmata (Scopoli) Fr. 3. Russula nigricans (Bull.) Fr. 4. Omphalia sp. 5. Peziza repanda Pers. 6. Wynnea gigantea Berk. et Curt. 7. Helvella crispa (Scop.) Fr. 8. Helvella epipploides Imai 9. Cordyceps militaris (L.) Link

• The Korean Journal of Mycology
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• v.37 no.2
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• pp.189-194
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• 2009

Author has carried out to survey on the fungal diversity from Yongnup swamp land, Yanggu-gun, Kangwon-do during the fruiting season over five years. During this survey 45 species and 3 varieties were recorded. Among them, Hygrocybe turunda (Peck) Bon var. sphagnophila (Peck) Bon was confirmed as an unknown species and Hygrocybe cruenta (Hongo) Hongo, Hydropus floccipes (Fr.) Sing. and Rhodophyllus setuliforme Kim Y. S. & Seok, S. J. were also found as rare species in Korea based on the examination of sporocarps and through previous literatures. Additional three species and two variety in Myxomycota, Hemitricha serpular (Scop.) Rostaf., H. clavata var. calyculata (Speg.) Y. Yamam, Badhamia affinis var. affinis Rostaf., Acyria cinerea (Bull.) Pers. and Metatricha vesparium (Batsch) Nann.-Bremk were also listed.

• Journal of the Korean Society for Railway
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• v.2 no.4
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• pp.5-16
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• 1999

1830년에는 영국의 Clarence가 16.4 kg/m의 압연레일을 제작하였다. 이것은 그후 영국에서 널리 사용되었던 우두(牛頭)레일(bull-head rail)이라 부르는 형의 원조라고도 한다. 1837년에는 영국의 J. Locke가 그림 9와 같은 쌍두(雙頭)레일(double head rail)을 고안하였다. 쌍두레일은 두부와 저부가 같은 단면으로 하여 레일 교환시에 상하를 전도하여 다시 사용할 목적이 있었다. 그러나, 목적에 반하여 경년(經年)과 함께 레일 하부의 레일을 지지하는 체어(chair)부에 접하는 개소가 손상하기 때문에 저부를 주행면으로 사용하기에는 지장이 생기기 쉽고, 이때문에 영국에서는 1844년에 고안된 우두레일로 바뀌었다. 이것은 두부와 저부의 단면이 대칭적이지 않고 두부가 약간 크다. 이 레일은 제조상 비교적 압연이 용이하고 냉각이 보다 빠르기 때문에 똑바른 레일을 얻기가 쉽지만, 레일의 횡방향 안정성 등에 문제가 있다. (중략)

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.174-180
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• 2002

A virtual reality technology for multipurpose numerical simulation is developed to reproduce and investigate a variety of ocean environmental problems in a 3D-Numerical Wave Tank. The governing equations for solving incompressible fluid motion are Navier-Stokes equation and continuity equation, and the Marker-Density function technique is adopted to implement the fully-nonlinear free-surface kinematic condition. The marine environmental situations, i.e. waves, currents, wind, etc., are reproduced by use of multi-segmented wavemaker on the basis of the so-called "snake-principle". In this paper, some numerical reproduction techniques for regular and irregular waves, multi-directional waves, Bull's-eye wave, wave-current, and solitary wave are presented, and a model test in motion with large amplitude of roll angle is conducted in the developed 3D-NWT, using a overlaid grid system.