• 해양환경안전학회지
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• 제28권2호
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• pp.307-313
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• 2022

지구 온난화와 기후변화에 대응하기 위해 국제적으로 재생 에너지의 개발이 확대됨에 따라 풍력발전의 비중도 점차 늘어가고 있다. 태양광발전에 비해 24시간 생산이 가능하지만 대형 풍력발전기를 대규모로 설치하기 때문에 주변의 레이더나 통신 장비들의 동작에 간섭을 일으키는 지에 대한 분석이 필요하다. 본 연구에서는 해상풍력 발전단지 외해를 항해하는 선박이 VHF 대역으로 조난 통신을 송신할 경우, 육지의 기지국에서 신호를 수신할 수 있는지를 분석하였다. 대상지역 주변의 수치지형도, 풍력발전기 캐드 모델, 풍력발전단지 배치도를 바탕으로 주변 해역 및 발전단지를 수치해석이 가능하도록 모델링하였다. 광범위한 지역에 대한 전파 분석에 적절한 고주파 해석기법 중 PO, SBR 기법을 적용한 전용 프로그램으로 전자파 간섭 여부를 분석하였다. 해상풍력 발전단지 외곽에서 송신한 VHF 대역 전자파에 대해 육상 기지국에서는 약간의 수신전력 저하는 있지만 기준치 이상의 전력을 수신하였다. 선박과 육상 기지국 사이의 가시선을 완전히 가리는 경우에 수신 전력의 저하가 발생하였으나, VHF대역이 파장이 길어 회절이나 반사 등의 효과로 육상 기지국까지 충분한 전파가 도달하는 것으로 판단된다.

• 한국정밀공학회지
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• 제24권9호
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• pp.103-109
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• 2007

LCD (Liquid Crystal Display) is widely used electronic product. It needs too many processes such as PECVD (Plasma Enhanced Vapor Deposition), Sputtering, Photo-lithography, Dry etch. Each process is important but inspection process is more important because most companies emphasis on the six sigma. Recently, LCD inspection system is composed with inlet, inspector, outlet air pads. LCD is inspected on air pad which is shooting air from air hole. This paper studies on pad design of air bearing for LCD inspection to minimize LCD fluctuation. This design is able to reduce fluctuation and then satisfies CCD inspectional range. Also inspection pad needs to adequate stable area.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.367-371
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• 2004

This paper describes development of automatic flight control system for an unmanned target drone which is operated by Korean army as for anti-air gun shooting training. Current target drone is operated by pilot control of on-board servo motor via remote control system. Automatic flight control system for the target drone greatly reduces work load of ground pilot and can increase application area of the drone. Most UAVs being operated now days use high-priced sensors as AHRS and IMU to measure the attitude, but those are costly. This paper introduces the development of low-cost automatic flight control system with low-cost sensors. The integrated automatic flight control system has been developed by integrating combining power module, switching module, monitoring module and RC receiver as an one module. The performance of automatic flight control system is verified by flight test.

• 수산해양기술연구
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• 제30권4호
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• pp.292-298
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• 1994

Catching performance of a mechanized pollock longline system compared with traditional one were examined in order to evaluate the practicality during two cruises in the Sokcho area. Mechanized longline system consists of random baiter, bait cutting machine, storage rails, and line hauler. Baiting efficiency of random baiter was 90-95% with 4-5kt shooting speed. Catching performance of the first experiment, salted sand lance only used as a bait. shows no significant difference between mechanized operation with use fresh sand lance as a bait caught significantly more pollock than traditional one with use salted sand lance (P<0.016). Improved catch rates were about 2 times. As soak time goes on, relative catching efficiency shows a steady increase up to 6~7 hours and thereafter gradually decrease.

• 한국군사과학기술학회지
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• 제16권3호
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• pp.268-276
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• 2013

The objective of this paper is to give a general understanding for the development flight test of Korean Utility Helicopter(KUH). This paper contains the contents of detailed flight test plan, the type of flight test, an introduction to main flight test area, and the overview of flight test results. At the beginning, more than 8,500 test points were identified for airworthiness certification to show the compliance for the KUH development requirements. However, the number of flight test points were optimized to 7,800 at the end. To accomplish the test objectives, about 860 flight test sorties had been performed, and more than 1,000 test sorties were consumed for trouble shooting. This paper also describes some major issues faced during development flight test phase.

• 한국정밀공학회지
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• 제16권10호
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• pp.217-224
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• 1999

Trouble shooting of modern machine tools equipped with sophisticated electronic as well as mechanical parts is so difficult that it is usually depends upon the experience and accumulated knowledge of the diagnosing persons. On the other hand, tool users are scattered in wide area, which makes it expensive for a machine tool maker to run a vast service network. An unmanned diagnosis system to which users can have access at all times could be an efficient alternative. For this purpose, a rule-based expert system for diagnosing machine tools is developed. This paper describes the structure of diagnostic knowledge, the rule firing mechanism, the diagnosis flow, and user query process. An example shows the feasibility of problem solving on site without help of a service expert from machine tool maker.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권12호
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• pp.520-526
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• 2005

Demands for the noise reduction of a transformer has been becoming an common issue because it has been used mainly at the residence area such as an apartment complex. This paper shows 2 trouble shooting examples that high noise sources were found out structural resonance of a transformer by 120Hz exciting frequency caused from magnetostrictive vibration of core. This paper presents that vibration data are very important to find noise source and how to avoid natural frequency of core and tank wall

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.513-518
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• 2001

This research has been performed to estimate the hunting motion hysteresis of railway passenger cars. An old and a new car with almost same structure are chosen as analysis models. To solve effectively a set of simultaneous equations of motion strongly coupled with creep relations, shooting algorithm in which the nonlinear relations are regarded as a two-point boundary value problem is adopted. The bifurcation theory is applied to the dynamic analysis to distinguish differences between linear and nonlinear critical speeds by variation of parameters. It is found that there are some factors and their operation area to make nonlinear critical speed respond to them more sensitivity than linear critical speed. Full-scale roller rig tests are carried out for the validation of the numerical results. Finally, it is concluded that the wear of wheel profile and the stiffness discontinuities of wheelset suspension caused by deterioration have to be considered in the analysis to predict hysteresis of critical speed precisely.

• Environmental Engineering Research
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• 제17권3호
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• pp.145-150
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• 2012

Pb-contaminated soil at a clay shooting range was analyzed by the sequential extraction method to identify metal binding properties in terms of detrital and non-detrital forms of the soil. Most of the metals in the soils existed as non-detrital forms, exchangeable and carbonate-bound forms, which could be easily released from the soil by a washing method. Therefore, the characteristics of Pb desorption for remediation of the Pb-contaminated soil were evaluated using hydrochloric acid (HCl) by a washing method. Batch experiments were performed to identify the factors influencing extraction efficiency. The effects of the solid to liquid (S/L) ratio (1:2, 1:3, and 1:4), soil particle size, and extraction time on the removal capacity of Pb by HCl were evaluated. Soil samples were collected from two different areas: a slope area (SA) and a land area (LA) at the field. As results, the optimal conditions at 2.8 to 0.075 mm of particle size were 1:3 of the S/L ratio and 10 min of extraction time for SA, and 1:4 of the S/L ratio and 5 min of extraction time for LA. The characteristics of Pb desorption were adequately described by two-reaction kinetic models.

• 한국측량학회지
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• 제40권3호
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• pp.195-206
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• 2022

The primary purpose of this study was to analyze assessment factors by identifying and prioritizing live fire shooting area requirements using the AHP (Analytic Hierarchy Process) technique. Derived assessment factors for candidate sites were divided into six categories. Of these, four categories (base-to-range distance, weapon danger area, range terrain, and size) were in the realm of physical geography while the remaining two (land use and proximity to habitation) fell under the general heading of human geography. A case study was also conducted to select several alternative firing ranges using derived factors. The optimal location was analyzed by evaluating the candidate site using each assessment factor. As a result, it was found that assessment factors applying to GIS (Geographic Information System) were able to effectively analyze a suitable location for relocation of the focal training facility, taking into consideration public-safety issues, training requirements, and residents' past and likely future complaints. Through this process, it can prevent the waste of time and effort in determining an optimal location for a live fire shooing range.