• 제어로봇시스템학회논문지
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• 제22권2호
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• pp.75-82
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• 2016

Visible light communication (VLC) using LED lamps is suitable for implementing an indoor positioning system in an indoor environment where the global positioning system (GPS) signal does not reach. In this paper, we present an indoor positioning system for mobile robots using a VLC beacon and fuzzy rules. This system consists of an autonomous mobile robot, VLC modules, and device application software. Fuzzy rules are applied to plan the global and local paths along which the mobile robot navigates indoors. The VLC transmitter modules are attached to the wall or the ceiling as beacons to transmit their own location information. The variable pulse position modulation (VPPM) algorithm is used to transmit data, which is a new modulation scheme for VLC providing a dimming control mechanism for flicker-free optical communication. The mobile robot has a receiver module to receive the location information while performing its mission in the environment where VLC transmitters are deployed.

• 대한전자공학회논문지
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• 제27권3호
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• pp.124-130
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• 1990

본 논문에서는 LSI/VLSI 레이아웃 설계 자동화를 위한 새로운 레이아웃 설계언어 HAN-LALA를 제안한다. HAN-LALA는 C언어를 확장하여 사용함으로써 레이아웃 기술이 용이하고 preprocessor없이 컴파일되므로 디버깅이 쉽고 설계 시간이 단축된다. 기술 독립적인 레이아웃 설계를 가능하게 하기 위하여 설계 규칙과 공정기술을 독립된 모듈로 구성한다. 또한 관련된 오브젝트들을 그룹으로 정의하여 그룹간 배치를 행하고, river routing, 금지 영역을 고려하여 배선 등의 다양한 배선 모듈을 제공하여 세부적인 레이아웃 기술이 없어도 오류 없는 설계가 가능하다.

• 한국환경교육학회지:환경교육
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• 제17권2호
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• pp.50-59
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• 2004

The environment subject has been introduced to the national curriculum in 1992 in order to overcome serious environmental problems. As using environmental issues in a class, the environment teachers inevitably face some conflicts associated with their role. By applying the questionnaire survey to 192 environment teachers, this study was conducted to understand their attitude and awareness of teacher role in the issue-based classes. The results showed that the majority(92.2%) of the participants had willingness to share their opinion on the issues under consideration with their students. This result implied that environment teachers maintain a position considerably different from the position (value-free and fair) that has been favored and suggested by previous research. This discrepancy may has been related to the unique history and identity of the environment subject in Korea. Despite their high level of willingness, the environment teachers also seemed to experience several barriers to managing issue-based classes effective such as time management, low students interest, and limited teaching materials. To make environmental issue-based classes interesting and meaningful, additional efforts are need to develop issue-based teaching modules and provide both teachers and teacher students with opportunities for learning those modules and teaching strategies.

• 한국가구학회지
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• 제28권3호
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• pp.145-155
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• 2017

This study explores developing a piece of modularized and multi-useful bed adapting PyeongSang followed by the last issue, 'a study on traditional Korean furniture, PyeongSang I' for the understanding of the furniture from theory and history. Adopted From the joints and ornament, the modularized elements were designed and developed in order to compose the head board, the side board, the foot board, and the seat bottom. The joints are sambang miter, samae miter, dado, and mortise and tenon, which are strong in holding the bed. And the ornament is lattice patterns like geokjamun and manjamun, elephant eyes patterns like ansangmun from the traditional furniture. Using the elements, the bed is composed with six modules which make people free and easy to move and transform them. Hence, the bed is multi-useful by using the double, the twin the single, and various sofas by the way to display them such as two, three, four, five, and six modules. And the bed was made of bright zelkova tree and dark heat treated ash expressing contrast of black and white, the design concept modern and easy to make many people access to them.

• 한국전기전자재료학회논문지
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• 제27권3호
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• pp.189-194
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• 2014

In this paper, PV modules using a low-temperature conductive film(LT-CF) as a bonding material between a cell and a solder free ribbon were produced and chracterized, which is more environmental-friendly, cost effective and high efficient. Mainly, filed electrical performance of PV modules using three different types of bonding material; a convetional solder ribbon(SR), a LT-CF and a light-capturing Ribbon(LCR) were compared to comfirm the feasibility of LT-CF as a bonding material. The filed test were conducted for 3 months and results were discussed in terms of amount of output energy production and efficiency.

• Journal of Welding and Joining
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• 제33권3호
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• pp.19-24
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• 2015

Joint properties of electric control unit (ECU) module using Sn-Cu-(X)Al(Si) lead-free solder alloy were investigated for automotive electronics module. In this study, Sn-0.5Cu-0.01Al(Si) and Sn-0.5Cu-0.03Al(Si) (wt.%) lead-free alloys were fabricated as bar type by doped various weight percentages (0.01 and 0.03 wt.%) of Al(Si) alloy to Sn-0.5Cu. After fabrications of lead-free alloys, the ball-type solder alloys with a diameter of 450 um were made by rolling and punching. The melting temperatures of 0.01Al(Si) and 0.03Al(Si) were 230.2 and $230.8^{\circ}C$, respectively. To evaluation of properties of solder joint, test printed circuit board (PCB) finished with organic solderability perseveration (OSP) on Cu pad. The ball-type solders were attached to test PCB with flux and reflowed for formation of solder joint. The maximum temperature of reflow was $260^{\circ}C$ for 50s above melting temperature. And then, we measured spreadability and shear strength of two Al(Si) solder materials compared to Sn-0.7Cu solder material used in industry. And also, microstructures in solder and intermetallic compounds (IMCs) were observed. Moreover, thickness and grain size of $Cu_6Sn_5$ IMC were measured and then compared with Sn-0.7Cu. With increasing the amounts of Al(Si), the $Cu_6Sn_5$ thickness was decreased. These results show the addition of Al(Si) could suppress IMC growth and improve the reliability of solder joint.

• International Journal of Railway
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• 제1권4호
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• pp.143-148
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• 2008

This paper is the output of a collaborative European project concerning the barrier free accessibility for disabled persons to regional and long distance trains in Europe. Disabled people represent around 13% of the population in Europe. This is approximately 63 million people. The range of disabilities includes people with reduced mobility including wheel chair users, viewing and hearing impaired people and other forms of impairment. Improving accessibility aims at contributing to the provision of public transport services to all citizens in an equitable way. The purpose of the project was to analyse and to evaluate the existing solutions at selected European railways for all required modules at the entrance (doors, information and safety solutions), to derive a design concept, to develop a mock-up in meeting the needs of rail travellers with the above mentioned impairments and to test it with user groups. The project also aims at deriving components for the determination of standards. The EUPAX Design Mock-up test was performed to verify the advantages of the layout of the train segment including the different modules such as access area (including the access door, gaps between platform and train as well as boarding aid devices), entrance vestibule, information systems inside and outside the train, emergency facilities, toilet with all conveniences and the additional test arrangements regarding push buttons, steps and emergency equipment. For this purpose a questionnaire was developed for the assessment of the EUPAX segment and the additional test arrangements. With the help of this questionnaire it was possible to execute a quantitative and qualitative evaluation. During three test phases 67 experts and handicapped persons from 6 countries have evaluated the Industrial Design mock-up based on this questionnaire. The test group covered persons from North (Denmark) to the South (Italy) and from the West (Spain) to the Middle of Europe (Germany). This is especially important for the generalization (harmonisation) of the results for all European countries. According to COST 335 the information for people with reduced mobility should be clear, concise, accurate and timely. So that all information can be received from persons, they must be transferred on at least two of the three possible ways (acoustical, visual, tactile), a so called "2-sense-principle". Based on the results ergonomic specifications/ solutions for the ergonomic design of the access area, the acoustic, visual and tactile information and the emergency devices including the emergency communication system were developed, related to the benefiting passenger groups.

• 대한산업공학회지
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• 제19권3호
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• pp.123-137
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• 1993

In this paper, an integrated approach is proposed to generate gouging-free Cartesian tool paths for machining sculptured surfaces from 3D measurement data. The integrated CAD/CAM system consists of two modules : offset surface module an Carteian tool path module. The offset surface module generates an offset surface of an object from its 3D measurement data, using an offsetting method and a surface fitting method. The offsetting is based on the idea that the envelope of an inversed tool generates an offset surface without self-intersection as the center of the inversed tool moves along on the surface of an object. The surface-fitting is the process of constructing a compact representation to model the surface of an object based on a fairly large number of data points. The resulting offset surtace is a composite Bezier surface without self-intersection. When an appropriate tool-approach direction is selected, the tool path module generates the Cartesian tool paths while the deviation of the tool paths from the surface stays within the user-specified tolerance. The tool path module is a two-step process. The first step adaptively subdivides the offset surface into subpatches until the thickness of each subpatch is small enough to satisfy the user-defined tolerance. The second step generates the Cartesian tool paths by calculating the intersection of the slicing planes and the adaptively subdivided subpatches. This tool path generation approach generates the gouging-free Cartesian CL tool paths, and optimizes the cutter movements by minimizing the number of interpolated points.

• 천문학회보
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• 제46권1호
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• pp.38.3-38.3
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• 2021

We are developing an optomechanical design of infrared telescope for the CubeSat and Unmanned Aerial Vehicle (UAV) which adapts the Linear Astigmatism Free- Three Mirror System in the confocal off-axis condition. The small entrance pupil (diameter of 40 mm) and the fast telescope (f-number of 1.9) can survey large areas. The telescope structure consists of three mirror modules and a sensor module, which are assembled on the base frame. The mirror structure has duplex layers to minimize a surface deformation and physical size of a mirror mount. All the optomechanical parts and three freeform mirrors are made from the same material, i.e., aluminum 6061-T6. The Coefficient of Thermal Expansion matching single material structure makes the imaging performance to be independent of the thermal expansion. We investigated structural characteristics against external loads through Finite Element Analysis. We confirmed the mirror surface distortion by the gravity and screw tightening, and the overall contraction/expansion following the external temperature environment change (from -30℃ to +30℃).

• 대한수학회보
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• 제57권5호
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• pp.1165-1176
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• 2020

Let M be a module over a commutative ring R. In this paper, we study Int(R, M), the module of integer-valued polynomials on M over R, and Int_M(R), the ring of integer-valued polynomials on R over M. We establish some properties of Krull dimensions of Int(R, M) and Int_M(R). We also determine when Int(R, M) and Int_M(R) are nontrivial. Among the other results, it is shown that Int(ℤ, M) is not Noetherian module over Int_M(ℤ) ∩ Int(ℤ), where M is a finitely generated ℤ-module.