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양순신(Soon Shin Yang),강연철(Yeon Chul Kang),손재연(Jae Yeon Son),오민환(Min Hwan Oh),김정호(Jeong Ho Kim),조진연(Jin Yeon Cho) 한국항공우주학회 2014 韓國航空宇宙學會誌 Vol.42 No.4
성공적으로 달 탐사를 수행하기 위해서는 달착륙선의 안전한 착륙이 보장되어야 한다. 그러므로 안전한 착륙을 저해하는 착륙 시 충격하중을 감소시키기 위해서는 효율적인 달착륙선 충격흡수장치를 설계해야 한다. 또한 더욱 현실적인 달착륙선 설계를 위해서는 달토양의 특성을 고려하는 것이 중요하다. 이에 본 논문에서는 달 토양의 특성을 반영한 달착륙선 착륙 해석 모델을 구축하고, 효율적인 충격력 감소를 위해 달착륙선의 충격흡수장치에 대한 최적설계를 수행하였다. 최적설계는 메타모델 기반의 순차적 근사 최적설계기법을 이용하여 수행하였으며, 최적설계 결과로 부터 본 연구에서 사용된 최적화 방법을 통해 달착륙선에 가해지는 충격력을 효과적으로 저감시킬 수 있음을 확인하였다. To successfully explore the moon by lunar lander, it is essential to guarantee the safe landing of lunar lander. Therefore, efficient shock absorption system of lunar lander should be designed in order to reduce landing impact force. Also, for more practical design of lunar lander, it is important to consider the effect of lunar regolith. In the line of thought, finite element model of lunar lander considering the effect of lunar regolith is developed. To reduce landing impact force, optimization of shock absorption system for lunar lander has been carried out. In optimization, sequential approximate optimization method based on meta-model is used. Through the result of optimization, it is verified that landing impact force on lunar lander can be efficiently reduced by the present optimization procedure.
손황진(Hwang-Jin Son),양순철(Soon-Chul Yang),김태규(Tae-Gyu Kim),김수태(Soo-Tae Kim),정윤교(Yoon-Gyo Jung) 한국기계가공학회 2008 한국기계가공학회 춘추계학술대회 논문집 Vol.2008 No.-
Drilling is important machining process occupied over 30% in manufacturing industry. But, drilling process have many problems, such as decreasing of machining accuracy, quality of surface roughness and roundness, etc. Therefore many studies are carried out to solve these problems. In this study, three multi facet drills(MFD) which are improved chisel point shape of standard drill(STD) are developed. Performance of multi facet drills(MFD) which is developed in this study is discussed viewpoint of surface roughness, drilling force, roundness of machined hole and chip shapes. From obtained results, it is confirmed that performance of rough flute drill(RFLD) type is most excellent among used multi facet drills.
손황진(Hwang-Jin Son),양순철(Soon-Chul Yang),황종대(Jong-Dae Hwang),정윤교(Yoon-Gyo Jung) 한국기계가공학회 2009 한국기계가공학회지 Vol.8 No.2
Drilling operation is such an important machining process, which has been wildly applied to the industry, occupied over 30% of whole industry. However, there are many aspects of drilling process should be improved, such as increases of thrust force, surface roughness, and roundness, ect. In this study, we are aiming to reduce the thrust force, surface roughness, and roundness in drilling process. For this purpose, multi facet drills (MFD) of three types that are modified from standard drill (STD) are developed. The first type is multi stair drill (MSD) with shape of stair on relief plane. The second type is rough facet drill (RFD) with shape of round on relief plane. The third type is rough flute drill (RFLD) with shape of round on flute plane. For three types of MFD, we were carried out performance evaluation from the perspective of thrust force, surface roughness and roundness of machined hole. From obtained result, we could confirmed that performance of rough flute drill (RFLD) type is most excellent.
LPCVD P₂O5 - SiO₂ 집적광학박막의 제작 및 특성연구(2) : TMPate와 PH₃의 비교
정환재(Hwan Jae Jung),이형종(Hyung Jong Lee),이용태(Yong Tai Lee),전은숙(Eun Suk Jeon),김순창(Soon Chul Yang),양순철(Soon Chang Kim) 한국광학회 1995 한국광학회지 Vol.6 No.3
Low Pressure Chemical Vapor Deposition으로 TEOS, TMPate, PH₃을 이용하여 Si을 기판으로한 집적광학용 P₂O_5-SiO₂(PSG)박막을 만들었으며 P 첨가제인 TMPate와 PH₃의 사용에 따른 증착률, 굴절률, 균일도 등의 특성을 조사 및 비교하였다. TMPate에 의한 PSG 박막은 증착률이 55Å/min으로 PH₃에 의한 PSG 박막의 값인 90Å/min 보다 작았으며, 상대적으로 TMPate-PSG의 두께 균일도는 2%로 PH₃-PSG의 값인 4.5%보다 작아 균일도면에서 훨씬 우수하였다. TMPate-PSG의 굴절률은 파장 633㎚에서 1.445~1.468이였으며, PH₃-PSG는 1.459~1.476으로 TMPate-PSG 보다 높은 굴절률 값을 얻을 수 있었다. We made P₂O5 - SiO₂ films on silicon for integrated optics application by low pressure chemical vapor deposition using TEOS(tetraethylorthosilicate), TMPite(trimethylphosphite) and phosphine(PH₃). And We studied and compared between TMPite and PH₃ as a dopant of P in PSG films in the aspect of the deposition characteristics. Deposition rate of TMPate-PSG films was 55 Å/min which was smaller than 90 Å/min, that of PH₃-PSG films. Thickness deviation of TMPate-PSG films was 2% and that of PH₃-PSG was 4.5%. So TMPate-PSG films had a good quality in thickness uniformity. The range of refractive index was controlled from 1.445 to 1.468 at 633 ㎚ in TMPate-PSG films and it was controlled from 1.456 to 1.476 in PH₃-PSG films.
LPCVD P₂O5 - SiO₂ 집적광학박막의 제작 및 특성연구 (1) : TEOS와 TMPite의 LPCVD
정환재(Hwanjae Jung),이형종(Hyung Jong Lee),임기건(Kiegon Im),전은숙(Eun Suk Jeon),정이선(Yisun Chung),김진승(Jin Seung Kim),양순철(Soon Chul Yang) 한국광학회 1993 한국광학회지 Vol.4 No.3
Si 기판 위에 low pressure chemical vapor deposition 방법에 의해 TEOS (tetraethylorthosilicate)와 TMPite (trimethylphosphite)를 재료로하여 집적광학용 P₂O_5-SiO₂ 박막을 만들고 그 특성을 조사하였다. TEOS의 반응에 TMPite가 참여함으로서 반응활성화에너지는 54.6㎉/mole에서 39.2㎉/mole로 크게 낮아졌으며 박막의 증착속도와 P 농도는 TMPite의 유량에 비례하여 증가하였다. 또한 증착용도가 높을수록 박막의 증착속도는 증가하나 P 농도는 감소하였다. 제작된 박막의 굴절률은 P 농도 1wt% 당 0.0019로 P 농도에 비례하여 증가하였다. 측정된 박막 불균일도는 두께 ±7% 및 P 농도 ±0.5 wt% 정도로서 이러한 불균일성은 주로 TMPite의 불균일한 수송에 기인함을 보였다. 또한 P 농도가 10 wt%이상인 박막을 대기중에 장시간 노출하면 표면에 인산이 석출됨을 확인하였다. We made P₂O_5-SiO₂ films on silicon for integrated optics application by low pressure chemical vapor deposition using TEOS (tetraethylorthosilicate) and TMPite (trimethylphosphite) and studied the deposition characteristics. The activation energy of the reaction was changed from 54.6㎉/mole to 39.2㎉/mole by incorporating the TMPite into the reaction of TEOS. The deposition rate and the P concentration of films increased in proportion to the flow of TMPite. As the deposition temperature increased, the deposition rate of the films increased but the P concentration decreased. The fabricated films showed the increase of refractive index of 0.0019 per 1 wt% of P concentration. The nonuniformity of films was ±7% in thickness and ±0.5 wt% in P concentration and we showed this' nonuniformity is due to the nonuniform transport of TMPite. The films of more than 10 wt% P concentration developed phosphoric acid on its surface when exposed to air for long time.
Free Electron Laser in Dielectric-Loaded Waveguide
Yang, Soon-Chul,Jung, Yang-June 木浦大學校基礎科學硏究所 1988 基礎科學硏究誌 Vol.6 No.-
A free electron laser (FEL) with a dielectric-loaded waveguide operating in undulator (multiple mirror) field is analyzed. The stability properties are investigated self-consistently on the basis of the linearized Vlasov-Maxewll equations. Using appropriate boundary conditions a dispersion relation is derived in the low density approximation and is numerically solved. In the case of the short wiggler wavelength mode, the frequency of FEL is greatly enhanced in mildly relativistic electron beam with the appropriate choices of physical parameter values. Therefore, the intense submillimeter microwave might be produced by making use of a mildly relativistic electron beam. A wide band free electron laser amplifier is also possible by the proper choice of the external parameters, such as wiggler wavenumber, dielectric constant, and beam energy.
Point Matching Equations of Plane-Cut Circular Dielectric Waveguides for Computer Analysis
Yang,Soon-Chul 木浦大學校 基礎科學硏究所 1994 基礎科學硏究誌 Vol.12 No.-
Circular waveguides cut on a plane perpendicular to the symmetry axis are studied. We obtain a set of point matching equations, including the radius of curvature of core surface and the height of core, which are derived by applying an appropriate choice of boundary points, field continuity conditions at these points, and the approximation of a finite sum for the vector solution expanded as circular harmonics. By the symmetry of these waveguides, the waveguide modes are separated into two groups with the even or odd parity of the X-component of electric field. When the refractive index ratio of core and cladding approaches unity, two groups are degenerate. This point matching equations derived have generality for shape of plane-cut circular waveguides. This work is more useful when the refractive index difference of core and cladding is large or when the vector properties are important for application of these waveguides to specific cases.
Eigenmodes in Cylindrical Dielectric Loaded Waveguide from Potential Boundary Conditions
Yang,Soon-Chul 木浦大學校基礎科學硏究所 1986 基礎科學硏究誌 Vol.4 No.-
The boundary conditions of the scalar potential and vector potential at the vacuum-dielectric interface in a cylindrical dielectric-loaded waveguide are derived. It is shown that the potential boundary conditions obtained are equivalent to the field boundary conditions. Using the potential boundary conditions the properties of eigenmodes capable of propagating through the dielectric loaded waveguide are investigated and compared with the results from the field boundary conditions.