• 한국진공학회지
• /
• 제15권5호
• /
• pp.451-457
• /
• 2006

벌집형 양극 셀 구조를 가지는 스퍼터 이온펌프를 제작하여 그 성능을 측정하고 기존의 원통형 구조와 비교하였다. 원통형 구조는 원통과 원통 사이에 기체의 이온화에 크게 기여하지 못하는 공간(dead space)이 전체의 10 % 정도 존재하는데, 벌집형 구조에서는 이러한 공간이 없으므로 이론적으로는 배기성능 또한 최대 10 % 정도 향상될 것으로 예측된다. 이러한 점에 착안하여 본 연구에서는 원통형 및 벌집형 셀 구조의 스퍼터 이온펌프를 제작하여 배기성능을 측정하여 서로 비교하였다. 그 결과 벌집형 구조가 원통형 구조에 비해 압력 구간에 따라서 $5%{\sim}11%$ 정도 배기속도가 높은 것으로 나타났다.

• 태양에너지
• /
• 제17권2호
• /
• pp.23-33
• /
• 1997

This paper reviews the advanced solar cell structures used in space. These are the structures which incorporate the back surface field and reflectors with very shallow and lightly doped emitters. Their use in space has shown that the thinner cells are more resistive to radiation damage than the thicker ones. It has been found that the charged particles affect both the surface and bulk of the cells used in space. This causes degradation in the output power, which in effect, can be explained by the degrading diffusion length of the cells. The PERL cells showed higher BOL(beginning of life) efficiency and almost the same EOL(end of life) efficiency as structures with wrap-around contact configuration fabricated on 10 ${\Omega}cm$ resistivity substrates. This observation lead to a conclusion that, the space cells do not necessarily need to have very high BOL efficiency except in specific missions which require such.

• Journal of Astronomy and Space Sciences
• /
• 제31권3호
• /
• pp.205-214
• /
• 2014

In this study, a star identification algorithm which utilizes pivot patterns instead of apparent magnitude information was developed. The new star identification algorithm consists of two steps of recognition process. In the first step, the brightest star in a sensor image is identified using the orientation of brightness between two stars as recognition information. In the second step, cell indexes are used as new recognition information to identify dimmer stars, which are derived from the brightest star already identified. If we use the cell index information, we can search over limited portion of the star catalogue database, which enables the faster identification of dimmer stars. The new pivot algorithm does not require calibrations on the apparent magnitude of a star but it shows robust characteristics on the errors of apparent magnitude compared to conventional pivot algorithms which require the apparent magnitude information.

• 천문학회보
• /
• 제31권1호
• /
• pp.23.2-23.2
• /
• 2006

• 한국수소및신에너지학회논문집
• /
• 제31권5호
• /
• pp.444-452
• /
• 2020

This study investigated the cathode catalyst of direct borohydride/hydrogen peroxide fuel cells for space exploration. Various catalysts such as Au, Ag, and Ni were supported on multiwalled carbon nanotubes (MWCNTs). Various techniques, such as transmission electron microscopy, Brunauer-Emmett-Teller method, scanning electron microscopy, and X-ray diffraction were conducted to investigate the characteristics of the catalysts. Fuel cell tests were performed to evaluate the performance of the catalysts. Ag/MWCNTs exhibited better catalytic activity than the Ni/MWCNTs and better catalytic selectivity of the Au/MWCNTs. Ag/MWCNTs presented good catalytic activity and selectivity even at an elevated operating temperature. The performance of Ag/MWCNTs was also stable for up to 60 minutes.

• Applied Microscopy
• /
• 제24권4호
• /
• pp.52-60
• /
• 1994

The developing ovarian oocyte of Dendrolimus spectabilis has been studied by using electron microscopical techniques. After yolk formation the vitelline membrane was laid down in the intercellular space between the follicle cell and the oocyte. But before the vitelline membrane formation the granules with high electron density that the vitelline membrane precusor are observed in the follicle cell. At the late vitellogenesis stage these granules were transported into the intercellular space between the follicle cells and the oocyte. These granules fuse to each other and larger bodies which eventually produce the vitelline membrane. The vitelline membrane was distinguished into the light inner and dark outer membrane. Next the chorion was laid down. It was apparent that the chorion was laid down in the intercellular space immediately adjacent to the vitelline membrane, and that it was formed by the follicle cells only.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제43권3호
• /
• pp.191-196
• /
• 2017

Squamous cell carcinoma of the buccal mucosa has an aggressive nature, as it grows rapidly and penetrates well with a high recurrence rate. If cancers originating from the buccal mucosa invade adjacent anatomical structures, surgical tumor resection becomes more challenging, thus raising specific considerations for reconstruction relative to the extent of resection. The present case describes the surgical management of a 58-year-old man who presented with persistent ulceration of the mucosal membrane and a mouth-opening limitation of 11 mm. Diagnostic imaging revealed a buccal mucosa tumor that had invaded the retroantral space upward with involvement of the anterior border of the masseter muscle by the lateral part of the tumor. In this report, we present the surgical approach we used to access the masticator space behind the maxillary sinus and discuss how to manage possible damage to Stensen's duct during resection of buccal mucosa tumors.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
• /
• pp.972-974
• /
• 1993

This paper presents a new method to automatically design fuzzy logic controller(FLC). The main problems of designing FLC are how to optimally and automatically select the control rules and the parameters of membership function (MF). Cell state space algorithms (CSS), differential competitive learning (DCL) and multialyer neural network are combined in this paper to solve the problems. When the dynamical model of a control process is known. CSS can be used to generate a group of optimal input output pairs(X, Y) used by a controller. The(X, Y) then can be used to determine the FLC rules by DCL and to determine the optimal parameters of MF by DCL and to determine the optimal parameters of MF by multilayer neural network trained by BP algorithm.

• 산업경영시스템학회지
• /
• 제19권39호
• /
• pp.255-264
• /
• 1996

This Paper presents a heuristic algorithm for machine-part group formation considering part production information (Production volume, roution sequence, unit operation time, facility size) in cellular manufacturing logistics system. In general, factory space is restricted within limited size when cells are located. A twofold heuristic algorithm is developed for considering factory space restrictions of located cells. The first phase is a aggregation procedure to minimize inter cell movement for satisfactoring space restriction. The second phase is a rearrangement procedure to maximize line balancing efficiency between machines within the cell and non assigned machine during first phase. Numerical example is presented to verify the efficiency of proposed algorithm.

• International Journal of Aeronautical and Space Sciences
• /
• 제4권1호
• /
• pp.9-18
• /
• 2003

In this work, a closed-form analysis is performed for the structural response of coupled composite blades with multi-cell sections. The analytical model includes the effects of shell wall thickness, transverse shear, torsion warping and constrained warping. The mixed beam approach based on Reissner's semi-complementary energy functional is used to derive the beam force-displacement relations. The theory is validated against experimental test data and other analytical results for coupled composite beams and blades with single-cell box-sections and two-cell airfoils. Correlation of the present method with experimental results and detailed finite element results is found to be very good.