• 베이커리
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• no.6 s.455
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• pp.54-55
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• 2006

오는 5월 27일 개최되는 제6회 전국크림치즈제품실기경연대회 본선에 앞서 지난 4월 25일 (사)대한제과협회 전국 11개 지회에서는 본선에 진출하는 총 50작품을 가려내기 위해 치열한 예선전이 펼쳐졌다. 올해 처음으로 실시된 지역별 예선의 뜨거웠던 현장을 취재했다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.4
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• pp.415-423
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• 2003

The hydrodynamic instability of the three-dimensional boundary-layer over a rotating disk has been numerically investigated for these flows; Ro = -1, -0.5, and 0, using linear stability theory. Detailed numerical values of the disturbance wave number. wave frequency. azimuth angle. radius (Reynolds number, Re) and other characteristics have been calculated for the pre-swirl flows. On the basis of Ekman and Karman boundary layer theory, the instability of the pre-swirl flows have been investigated for the unstable criteria. The disturbance will be relatively fast amplified at small fe and within wide bands of wave number compared with previously known Karman boundary-layer results. The flow (Ro =-0.5) is found to be always stable for a disturbance whose dimensionless wave number is greater than 0.9. It has a larger range of unstable interval than Karman boundary layer and can be unstable at smaller Re.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.112-113
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• 2018

스트레스는 스트레스 요인에 반응하는 신체와 정신의 변화과정으로, 외부의 자극을 받으면 혈압, 심박동수, 호흡수가 증가하게 된다. 이러한 생체신호로 인간의 스트레스 요인을 측정할 수 있다. 본 연구에서는 선박조종시뮬레이션을 이용해 예비(견습)도선사가 도선접안 중 체감하는 스트레스의 정도와 특성을 생체신호 변화를 활용하여 실증적으로 분석하였다. 선박조종시뮬레이션에서 추출한 엔진 사용량, 타각 사용량, 속력 및 예선 사용량과 스트레스 분석을 위해 Heart BPM, SDNN, RMSSD의 3가지 심박변이도 파리미터의 상관관계를 분석하였다. 분석결과, 6회 중 4회의 시뮬레이션에서 Heart BPM은 지속적으로 상승하고 SDNN은 하강하여 시간에 따라 스트레스가 상승하는 것으로 분석되었다. 특히 예선 사용시점에서 변화의 폭이 큰 것을 확인하였다. RMSSD는 단기주기(1분간격) 측정 파라메터로 실험자가 느끼는 순간의 위험에 따라 그래프 변화폭이 심한 것으로 분석되었다. 전체적으로 엔진, 타각, 예선의 사용시점에 따라 큰 변화를 보였으며, 실험자들의 선박운용 행위에 따라 생체신호 변화를 보였다고 사료된다. 분석결과를 바탕으로 도선사에게 스트레스를 미치는 요소를 판별하여 도선접안 중 스트레스가 높아지는 순간에 인적사고를 예방할 수 있는 시스템적 보완을 마련하고자 한다.

• The KSFM Journal of Fluid Machinery
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• v.5 no.3 s.16
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• pp.46-53
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• 2002

This paper reports an experimental investigation on a centrifugal compressor with the adjustable inlet guide vane. The compression system is composed of a radial impeller, a vaneless diffuser, and an IGV. The results have shown that surge line on the performance map is affected by the amount of prewhirl and the prewhirl has an effect on transient region between rotating stall and surge. The surge lines have been shifted toward the lower flow region with the increased positive prewhirl and the higher flow region with the increased negative prewhirl. During the unsteady performance test, it was also found that the transient region was reduced with the increased negative prewhirl, and weak signals of rotating stall were detected just before surge as the positive prewhirl was increased.

• The KSFM Journal of Fluid Machinery
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• v.7 no.3 s.24
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• pp.23-31
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• 2004

An experimental study on the performance and instability development characteristics of a centrifugal compressor equipped with an adjustable inlet guide vane has been performed with varying guide vane angles. The test was conducted at the design speed of 20,800 rpm for 6 guide vane angles : $-30^{\circ},\;-20^{\circ},\;10^{\circ},\;0^{\circ},\;10^{\circ},\;20^{\circ},\;30^{\circ}$. Unsteady pressures were measured using high-frequency pressure transducers at the inducer to investigate the instability phenomena such as rotating stall and surge inside the compressor. From the unsteady measurements, it is found that the transient process from rotating stall to surge was mainly affected by inlet guide vane angles. The results of the present study can be applied to the instability control of the centrifugal compressors using a adjustable inlet guide vane.

• Aerospace Industry
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• s.105
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• pp.34-37
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• 2009

국내 무인항공기 기술기반 구축을 위해 2002년부터 개최되었던 로봇항공기대회가 지식경제부 주최로 9월 26일 한서대학교 태안비행장(충남 태안 소재)에서 해외선발팀 1팀과 예선을 통과한 국내 6팀 등 총 7팀이 참가한 가운데 국제대회로 개최되었다.

• 베이커리
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• no.6 s.455
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• pp.142-143
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• 2006

푸드앤호텔아시아 2006 현장에서 아시아 최초로 아시아페이스트리컵이 개최돼 큰 화제를 모았다. 월드페이스트리컵의 아시아 지역예선으로 치러진 이번 대외에서 싱가포르와 말레이시아, 호주 등 모구 7개국이 참가해 열띤 경연을 펼쳐다. 아시아는 이제 내년 1월 프랑스 리옹에서 열리는 제 10회 월드 페이스트리컵을 향헤 뜻 깊은 한 걸음을 내딛었다.

• Journal of the Korean earth science society
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• v.26 no.6
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• pp.511-523
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• 2005

The purpose of this study is to analyze the 1st and 2nd Korea Earth Science Olympiad (KESO) items, in order to find informations to enhance item quality. To do this, internal and external item classification frameworks are developed. Item difficulty (P), discrimination index (DI), correlation, and reliability are estimated by using classical test theory. Generalizability is also estimated by applying the generalizability theory. The results of item classification are as follows: (1) ‘Geology’, ‘astronomy’ and ‘data analysis and interpretation’ are dominant in content and inquiry process domain, respectively. Nearly every item has textbook context. (2) There is no difference between the preliminary and final tests in terms of their thinking skills sections. (3) As a whole, the ratio of items with pictures is high in item representation. However, multiple-choice and short answer items are more common in preliminary competition, and essay type items are found more often in final competition. The ratio of simple items is high in middle school section and preliminary competition, but composite items are dominant in high school section and final competition. The findings of item analysis are as follows: (1) In the middle school section, P is low and DI is moderate. But in the high school section, there is a considerable differences between science high schools and other high schools in general. (2) The highest correlation is reported between the scores of meteorology domain and total score in middle school, whereas in high school astronomy domain and total score show the highest correlation. (3) General high school section show the highest Cronbach $\alpha$ and generalizability. (4) General high school section show acceptable generalizability coefficient (> 0.80), but middle and science high school section should increase the number of items to reach acceptable generalizability level.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.99-106
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• 2005

In this study, the electromagnetic characteristics of a flat-type two-dimensional proportional solenoid were analyzed by the magnetic reluctance method. The equivalent magnetic circuit equation for the solenoid was derived by modeling the reluctance of air gaps and magnetic structural components such as pole core, armature and yoke. It was solved iteratively because of the nonlinear magnetization properties of the iron parts. The solutions showed good agreement with experimental data. Based on the equivalent magnetic circuit equation, the influence of design parameters on the force-to-armature displacement curves was mathematically derived and experimentally verified. In this way, dominant design parameters could be analytically determined.

• Journal of Aerospace System Engineering
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• v.8 no.1
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• pp.1-6
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• 2014

The conventional hydraulic circuits for electro-hydrostatic actuators equipped with a single-rod cylinder can oscillate under overrunning load conditions. In this paper the oscillation problem encountered in the conventional hydraulic circuits for EHAs is analyzed and it is shown by simulation results that this problem can be solved by employing a counter balance valve instead of a pilot-operated check valve generally used in the conventional hydraulic circuits.