• 한국산학기술학회논문지
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• 제13권1호
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• pp.33-38
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• 2012

본 연구에서는 나선형 형태의 와이어를 자동차 무선통신(5.925GHz)용 차량 커넥터에 적용 가능성을 제안하였다. 이 나선형 와이어 형태의 커넥터 설계는 나선형 평균 반경, 나선형 피치, 나선형 와이어 자체의 반경, 나선형와이에서 접지 부분까지의 거리를 중요 설계인자로 판단하여 실시하였다. 이 같은 설계 해석 및 결과는 자동차 통신용 커넥터 설계를 위한 가장 적합한 나선형 와이어 치수 결정에 사용될 수 있을 것이다. 나선형 와이어가 삽입된 최적화된 자동차 WAVE용 커넥터는 삽입손실이 5.925GHz 대역에서 -0.76dB 이내로 발생되었다. 이 삽입손실 결과는 기존의 일반 커넥터에 비하여 21% 성능이 향상된 것이다. 따라서, 본 커넥터 해석결과는 자동차 통신을 위한 고주파대역의 최적 커넥터 설계에 유용하게 사용할 수 있을 것이다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권4호
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• pp.253-260
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• 1999

In this paper, the impedance characteristic of wire-plate pulsed plasma reactor was investigated by experiment. The experiment have carried out under the several conditions of voltage, wire length and wire-plate distance. The impedance of reactor wad decreased with increasing voltage and wire length. The nature of discharge in reactor was changed from streamer corona to spark with increasing incident energy, from which we understood the critical energy density between the two discharges. Fromthis experiment, we proposed the method for the impedance matching between pulse generator and pulsed plasma reactor. Additionally, we succeeded in the analysis ofstray inductance of 0.5MW reactor using EMTP (ElectroMagnetic Transients Program). This means that EMTP is also useful for the analysis of inevitable stray inductance of forthcoming a large scale reactor.

• 유통과학연구
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• 제17권9호
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• pp.25-33
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• 2019

Purpose - The purpose of the study was to seek to find out what factors having differences between paid membership customers (Costco membership) and general customers in retail industry. Since Costco operates differently from other conventional retailers, which is expected to have a substantial impact on consumers' preference of retail stores. Research design, data, and methodology - The survey conducted covered 1,000 adults in their 30s~50s living in Goyang and Gwangmyeong where Costco runs stores to determine the effects of Costco's local market-entry from consumer perspectives. 500 respondents were surveyed in each region and those working in the retail sector were excluded to ensure the objectivity of the answers. Results - Costco members in Goyang considered the price, bulk purchasing, and membership benefits as important criteria when choosing their retail store. On the other hand, as for Gwangmyeong, the non-member group's prominent characteristic was that they considered accessibility including travel distance and location and in-store amenities including food court services as important criteria for decision-making. Conclusion - Unique business model of Costco shows a statistically significant difference in terms of consumer awareness. the feature of Costco served as an critical criteria for consumers in their purchasing decision. Moreover, Bulk packaging purchases at Costco results in a strong supplementary relationship with neighborhood supermarkets.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.735-741
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• 2003

A simplified view of array design and application process was introduced. Array design is critical to achieve a successful phased array measurements. A planar microphone array is designed to produce optimum performance and also to fit economic requirement in integrating data acquisition system. Certain performance characteristics are of primary concern when designing arrays. These characteristics include array resolution, spatial aliasing and array sidelobe suppression. Every array has its directional pattern that shows such characteristics. Assuming that a monopole source is located in center, beam-patterns have been simulated varying measurement conditions such as number of sensors. array aperture size, distance between array and source, frequency of interest and so on. Sensor correction was conducted on very channel using magnitudes and phased of FRF with respect to a reference microphone channel. Then with a spiral type array, measurements have been made with two point sources of same frequency in order to investigate array resolving abilities. It is observed that higher frequency source achieves better resolution than lower one does.

• 한국정밀공학회지
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• 제18권5호
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• pp.105-111
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• 2001

The creep crack growth properties in 3.3NiCrMoV steel were investigated at 55$0^{\circ}C$ by using CT specimen under constant load and constant Ct condition that was held during crack growth of Imm distance. Ct lelied on load line displacement rate, C＊usually increased with crack length though load is reduced in order to maintain constant Ct value as crack growth and appeared scatter band. At constant load and Ct region, crack growth slope was 0.900 and 0.844 each, on the other hand C＊ slope was 0.480. Fully coalesced area(FCA) ahead of crack tip increased as Ct increase to the critical value, and after that value FCA decreased. For the tertiary creep stage of crack growth test, the most of displacement was due to the steady state creep, except only small part due to the primary creep and other effects. Therefore, tests were mainly interrupted in the tertiary stage to obtain high value of Ct.

• 물과 미래
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• 제29권2호
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• pp.167-178
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• 1996

하천 및 호소수 수질의 온라인 계측을 위한 수질자동측정망의 설계에서 측정위치와 항목의 선정은 전체시스템의 성능을 결정짓는 중요한 인자이다. 본 논문에서는 상수원유역의 상시수질감시 및 사전경보 기능을 갖는 측정망의 구축이 측정위치와 항목을 결정하는 방법을 연구하였다. 측정위치를 결정하기 위한 선정기준은 상수취수량과 고정오염원의 위치를 바탕으로 대상지역에 대한 거시적 후보지점을 선정한 뒤, 구체적인 지점은 오염물질 유하거리를 기준으로 단계적으로 결정한다. 측정항목은 유역의 오염특성과 수질오염사고 이력을 참고하되, 경제적인 측면을 고려하여 필수측정항목과 선택항목으로 나누어 위치별로 달리하는 방안을 제시하였다. 제안방법을 낙동강유역에 적용함으로써 측정망 구성과정을 예시하였다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2003년도 춘계학술논문발표회논문집
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• pp.248-254
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• 2003

저자들은 2003년 2월 18일 대구지하철 중앙로역에서 발생한 화재 시의 환자 이송현황의 분석을 통하여 다음과 같은 결론을 얻었다. 환자들이 이송된 의료기관은 주로 의료 기관의 규모가 크고, 이송 거리가 짧은 기관 중심으로 이송이 이루어졌다. 경증의 환자가 가깝고 규모가 큰 응급의료기관으로 이송됨에 따라, 중증의 환자가 멀거나 규모가 적은 응급의료기관으로 이송되어야 하는 상황도 있었으며, 병원도착전에 사망한 환자들은 거리에 상관없이 이송되었다. 따라서 적절한 중증도분류에 따른 적절한 의료기관으로의 이송이 향후 시행되어야 하며, 이를 위해서 초기 피난 및 대응과 이송방법과의 연계, 재해시 이송의 지역적 지침 확보 및 재해 정보와 응급의료기관 정보와의 연계 등이 향후 수정, 연구되어야 한다.

• 열처리공학회지
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• 제13권2호
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• pp.71-84
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• 2000

A study on adhesion and wear resistance of VC(vanadium carbide) coating on die steels, STD11 and STD61, has been carried out. The VC coating on the die steels was made by immersing them in molten borax bath, a kind of TRD(thermo-reactive deposition and diffusion). Adhesion strength and wear resistance were investigated using scratch test, indentation test and plate-disc test(Ogoshi type) respectively. The influence of sliding distance on the amount of wear has been determined and dominant wear mechanisms has been characterized using optical microscopy, scanning electron microscopy and EDS spectroscopy. The critical adhesion strength($L_c$) between VC coating layer and substrate(STD11) was increased to 60N($L_c$) in the scratch test. In the case of STD61, the strength increased to 24N. The wear resistance of VC coated die steels was excellent because the diffusion layer formed just below the coating layer. The dominant wear mechanism was identified as adhesive wear for VC coating die steels which were worn by combination of cracking and plucking of VC fragments and disc.

• 한국초전도ㆍ저온공학회논문지
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• 제17권1호
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• pp.1-5
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• 2015

With the increasing development of renewable energy, it is expected that large-scale renewable power would be transported from the west and north area of China to the east and south area. For this reason, it will be necessary to develop a wide-area power grid in which the renewable energy would be the dominant power source, and the power grid will be faced by some critical challenges such as long-distance large-capacity power transmission, the stability of the wide-area power grid and the land use problem for the power grid. The superconducting technology for power (STP) would be a possible alternative for the development of China's future power grid. In last decade, STP has been extensively developed in China. In this paper, we present an overview of the R&D of STP last decade in China including: 1) the development of high temperature superconducting (HTS) materials, 2) DC power cables, 3) superconducting power substations, 4) fault current limiters and 5) superconducting magnetic energy storage (SMES).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1078-1082
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• 1997

The distance in load parameter space to the closest voltage collapse point provides the worst case power margin and the left eigenvector identifies the most effective direction to steer the system to maximize voltage stability under contingency. This paper presents the results of the comparative performance study of the algorithms, which are applicable to a large scale power system, for computing the closest saddle node bifurcation (CSNB) point. Dobson's iterative method converges with robustness. However the slow process of updating the load increasing direction makes the algorithm less efficient. The direct method converges very quickly. But it diverges if the initial guess is not very close to CSNB. Zeng's method of estimating the approximate critical point in the pre-determined direction is attractive in the sense that it uses only using load flow equations. However, the method is found to be less efficient than Dobson's iterative method. It may be concluded from the above observation that the direct method with the initial values obtained by carrying out the iterative method twice is most efficient at this time and more efficient algorithms are needed for on-line application.