• Journal of Aerospace System Engineering
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• v.12 no.4
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• pp.9-17
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• 2018

With an aim of considering the warping restraint effect, the results of the comparative study for several cases on the correction of the warping functions for the theoretical analysis of composite thin-walled beams with chord wise asymmetric closed cross-sections are presented in this study. To solve this problem, it is necessary to correct the warping function so as to satisfy the warping equilibrium condition like 1) without moving the position of the pole, 2) with only modifying the shape function using the existing pole, and 3) with moving the position of the pole. The cross-sectional characteristics of the cases were compared with each other. Finally, the cases were compared in order to correct the warping functions. The case 2) was observed to be more speedy and simple in computation compared to others.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.485-491
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• 2012

The wall interference effects around the wind-turbine airfoil are experimentally investigated at low Reynolds numbers in a closed test-section wind tunnel. The test is performed at free-stream velocities from 10 to 31 m/s, which correspond to Reynolds numbers ranging from $1.5{\times}10^5$ to $4.6{\times}10^5$ based on chord of the airfoil. The blockage-area ratios, which is the ratio of the chord to the test-section width, are 27.8%, 38.5%, 41.7%, 45.5%, and 55.6%. The test results for the airfoil show that the transition point on the airfoil surface tends to move backward due to wall interference. The wall pressures for an adequate interference correction by a measured-boundary-condition method are desirable more than three times region of the chord before and after around the reference center.

• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.51-59
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• 2019

Subsequently, Part I [1], which was about the single-cell model, a composite thin-walled beam with a multi-cell of chord-wise asymmetric cross-section, was selected in this study. Moreover, the theoretical dynamic characteristics of the model were analyzed. For this analysis, mathematical modeling was performed by considering the warping restraint effects, transverse shear effects, taper ratio and cross-section ratio. Similar to part I, the mass, stiffness coefficients and Eigen frequencies of the multi-cell section considered were investigated. In particular, the comparison between the multi-cell and single-cell sections and the effects of the cross-section ratio and taper ratio of the model on the Eigen frequencies were analyzed. However, the results compared when the asymmetry of the section was considered and warping function were not corrected.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.36-41
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• 2005

The aerodynamic characteristics of the oscillating airfoil(NACA0012) were measured by experimental methods by using the airfoil oscillating test rig installed at KARI 1m wind tunnel. The chord of the airfoil is 0.2m and the span is 0.75m. The lift and pitching moments were calculated by integrating the surface pressure measured by strain-gage type pressure sensors. The test condition is like this : the reduced oscillating frequency(k) < 0.1, Re ~ 820,000, Mach < 0.25. The test results were compared with the reference data published by other facilities.

• Korean Security Journal
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• no.4
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• pp.169-187
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• 2001

NGOs occupy so high international position that it is said the age of NGOs or Renaissance of NGOs has came. Recently, they continuously succeeded in hindering and blocking large-scale international events through their violent struggles. This paper studied the concept of NGO, examples of NGO struggles during recent international events and stated anticipated struggles during ASEM III and their trend. Thereafter, with future prospect of NGO activities, some measures for successful 2002 World Cup and 2005 APEC were provided in this paper. The contents of this paper is as follows ; Chapter I : Introduction Chapter II : The concept of NGO and aspects of their struggles during recent international events Chapter III : Struggles during the 3rd ASEM, Seoul and their trend Chapter IV : Future prospect of NGO activities Chapter V : Conclusion

• Journal of Korean Medical classics
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• v.18 no.3 s.30
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• pp.126-135
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• 2005

통과분석(通過分析)${\ulcorner}$금궤요약심전${\lrcorner}$경병조문중우재경적주석(痙病條文中尤在痙的註釋), 득출여하결론(得出如下結論) 1. 경병적원인유이(痙病的原因有二) : 외인시태양풍한중감한습(外因是太陽風寒重感寒濕); 내인시혈기음양적손상(內因是血氣陰陽的損傷), 단진액부족시기공통지처(但津液不足是其共通之處). 2. 경병기본속우표병(痙病基本屬于表病), 출현심맥시인감수습사소치(出現沈脈是因感受濕邪所致). 3. 경병(痙病), 출현강직시인감수풍사(出現强直是因感受風邪). 4. 강경유오한증상(剛痙有惡寒症狀), 단유가능인위표실증무오한증상(但有可能認爲表實證無惡寒症狀), 고장원문중적'반'자직접인용과래설명(故將原文中的反字直接引用過來說明). 5. '기맥여고'화'폭복장대'시풍사거이습사잔존적시후출현적('其脈如故’和‘暴腹腸大'是風邪去而濕邪殘存存的時侯出現的). 6. 경병적양명어열증가사용대승기탕(痙病的陽明瘀熱證可使用大承氣湯), 기병불시위료거제조실(其幷不是爲了去除燥實), 이시위료하양명어열(而是爲了下陽明瘀熱), 고실제상사용대승기탕적시후요소심근신(故實際上使用大承氣湯的時候要小心謹愼).

• Journal of Korean Medical classics
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• v.18 no.3 s.30
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• pp.36-54
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• 2005

소통과팔회혈적고찰(素通過八會穴的考察), 득도료여하적결론(得到了如下的結論). 기일시(其一是), ${\lceil}$령추(靈樞) 사해(四海)${\rfloor}$ 편적사해(篇的四海), 유관여(有關與) ${\lceil}$난경(難經)${\rfloor}$적팔회(的八會), 사해가분위팔회(四海可分爲八會), 양자적관계가이인위여하(兩者的關係可以認爲如下). 수곡지해부회(水穀之海府會) 장회(藏會), 혈해(血海)-혈회(血會) 맥회(脈會), 수해(髓海)-수회(髓會) 골회(骨會) 근회(筋會), 기해(氣海)-기회(氣會). 기이시(其二是), 기해여기회(氣海與氣會), 내경여난경동작단중, 이차기병증역유공통점(而且其病症亦有共通點). 기삼시(其三是), 혈회여맥회시혈해분출적(血會與脈會是血海分出的). 격유혈취시혈회, 기혈속우배유혈(其穴屬于背兪穴), 여심간비폐유관(與心肝脾肺有關). 태연혈취시맥회(太淵穴就是脈會), 기부위시촌구맥(其部位是寸口脈), 소이유관여혈(所以有關與血), 기사시(其四是), 부회중완혈시위적모혈(府會中脘穴是胃的募穴), 장회장문혈시비적모혈(藏會章門穴是脾的募穴), 소이근수곡지해적위유관. 기오시(其五是), 관찰수해적병증(觀察髓海的病症), 가이추론수해분수회골회근회(可以推論髓海分髓會骨會筋會). 관어수회적혈(關於髓會的穴), 의서불일치(醫書不一致), 단옥침혈시여뇌부위상근(但玉枕穴是與腦部位相近), 기주치증야유사(其主治證也有似), 소이이옥침혈인위수회(所以以玉枕穴認爲髓會). 관어골회혈역유양개주장(關於骨會穴亦有兩個主張), 수요갱다적연구(需要更多的硏究).

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.13-16
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• 2012

본 논문에서는 항공기의 제어 안정성(Control Stability)과 조종성(Controllability), 그리고 기계 하중을 줄여 구조와 공기역학적인 안정성을 향상시키기 위해 고양력장치(High-lift Device)인 플랩에 탭이 추가된 익형을 설계하였다. 이 과정에서 한정된 해석자원 때문에 많은 설계조건을 해석하는데 어려움이 있었다. 이를 해결 하기위해 얇은 익형 해석(Thin Airfoil Theory)을 이용하여 지정된 설계구속조건을 통해 시위선을 지정하고 이를 바탕으로 두께를 부여하여 최종적인 익형을 설계하였다. EDISON CFD 2.0 Solver를 이용해 최종 설계한 익형의 성능을 해석하였다. 이를 바탕으로 플랩만 존재하는 익형에 비해 양력손실률이 15%이하로 감소하고, 힌지 모멘트가 최소인 공기역학적 익형을 산출하였다.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.21-24
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• 2012

본 논문은 HPA(Human Powered Aircraft) 제작 계획서를 작성하기 위해 프로펠러에 사용하는 에어포일을 작년에 접하게 된 EDISON-CFD 분석을 이용하여 기존에 X-foil로 얻어진 날개 익형에 대한 양력계수와 항력계수, 양항비와 비교하였다. 프로펠러 허브로부터 거리에 따른 단면에 해당하는 레이놀즈 수, 마하수, 받음각, 시위길이를 고려하여 에어포일을 분석해 보았다. 그 결과를 통해 프로펠러 에어포일을 선정하는데 많은 도움이 되었다. EDISON-CFD 분석에 대해 좀 더 공부하는 계기가 되어 우리 팀이 앞으로 졸업논문을 쓰는데 많은 도움이 될 것이다.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.121-124
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• 2012

비정상 유동 해석을 수행하는데 있어서 비정상 Navier-Stokes 방정식을 적용한 결과와 정상 N-S 지배 방정식을 적용한 결과의 차이를 비교하려한다. 적용하고자 하는 비정상 유동은 대칭형 에어포일 NACA0012 에어포일 주위 유동으로 정하였으며, 이 때 에어포일 시위(chord) 길이와 자유류(free stream) 속도 기준으로 Re=100,000에 해당한다. 계산결과 비정상 지배 방정식을 적용한 경우 비정상 유동박리(flow separation)를 모사 할 수 있었으며, 평균 양력계수($C_L$)와 항력계수($C_D$)는 실험치와 비교적 잘 일치하였다. 하지만 정상 N-S 방정식을 적용했을 경우 비정상 유동을 모사하기 어려웠으며 평균양력, 항력계수도 실험치와 차이를 보였다. 이러한 결과는 비정상 유동 해석시 시간에 따라 변화하는 유동의 특성을 고려해 비정상 N-S 지배 방정식을 적용해야한다는 사실을 보이고 있다.