• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.492-497
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• 2000

This paper focuses on the weight minimization of radial gate, as an extention of the previous work. Radial gates are commonly used to regulate the flow-rate of general purpose dams, due to its simplicity in manufacture and control. The present study identifies the optimum position of support point for 2 and 3 arm type radial gate, which guarantees the minimum weight satisfying strength constraint condition. These optimum designs are then compared with previously constructed radial gates. The results indicate that the weights of the optimized radial gates reduce by about 20%, compared to those of the conventionally designed radial gates.

• 한국항공운항학회지
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• 제24권3호
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• pp.48-54
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• 2016

This paper proposes a prediction model of air traffic controller's take-off clearance under mixed mode runway operations. The proposed model has its purpose on the better prediction of the air traffic controller's clearance on take-offs of departure aircraft by considering various factors. For this purpose, support vector machine classification algorithm is used for the proposed model. The proposed model is applied to real air traffic operations to demonstrate its performances.

• 한국통신학회논문지
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• 제37권5A호
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• pp.279-289
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• 2012

Characteristics, such as the support limit and distortions, of minimum mean-squared error (MSE) N-level uniform and nonuniform scalar quantizers are studied for the family of the generalized gamma density functions as N increases. For the study, MSE-optimal scalar quantizers are designed at integer rates from 1 to 16 bits/sample, and their characteristics are compared with corresponding asymptotic formulas. The results show that the support limit formulas are generally accurate. They also show that the distortion of nonuniform quantizers is observed to converge to the Panter-Dite asymptotic constant, whereas the distortion of uniform quantizers exhibits slow or even stagnant convergence to its corresponding Hui-Neuhoff asymptotic constant at the studied rate range, though it may stay at a close proximity to the asymptotic constant for the Rayleigh and Laplacian pdfs. Additional terms in the asymptote result in quite considerable accuracy improvement, making the formulas useful especially when rate is 8 or greater.

• Journal of the Korean Data and Information Science Society
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• 제21권1호
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• pp.173-177
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• 2010

It is well known that if the parent distribution has a nonnegative support and has increasing failure rate, then all the order statistics have increasing failure rate (IFR). The result is not necessarily true in the case of bivariate distributions with dependent structures. In this paper we consider a symmetric bivariate exponential distribution and show that, two marginal distributions are IFR and the distributions of the minimum and maximum are constant failure rate and IFR, respectively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.804-809
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• 2001

Optimal design of a portable structure which supports impact loading is presented. The structure requires impact loading capability, stiffness and minimum weight for portability. A collapsible tripod structure with locking mechanism is suggested. Taguchi method has been used to identify the most important design variables and the initial design. Subsequent optimization yields additional weight reduction under stress and displacement constrains.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2188-2191
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• 2003

이 논문에서는 라플라스 밀도함수에 대한 최적 홑양자기 지지역은 양자점의 개수와 로그선형 관계가 있음을 증명한다. 그리고, 극상한값을 유도하여 최적 지지역의 로그선형 증가가 어떤 상수값을 초과하지 않음을 증명한다. 이 결과들로부터, 학계에 경험적으로 알려져 왔던 최적 지지역의 로그선형 증가를 증명한다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.449-451
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• 2002

We reported the algorithm of driving scheme that enhances moving picture property by improving gray-to-gray response time. Here, we report result of simulation for estimation of driving voltage to reduce response time, and experimental result. We investigated optimization of algorithm so that minimum size of LUT can support to reducing the gray-to-gray response time within 1 frame period, and with single algorithm it is possible to apply the algorithm to various kinds of LC material. So in our system there is no external EEPROM.

• Tribology and Lubricants
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• 제31권5호
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• pp.221-228
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• 2015

It is possible to prevent a piston from contacting the cylinder by changing the shape of the piston or by applying micro-textures, such as micro-grooves or micro-holes, over the piston surface. Usually, the minimum radial clearance reaches its minimum value at the beginning of the suction stroke because the pressure around the piston is low and almost axisymmetric such that the net pressure force on the piston is not sufficiently high to support the piston from touching the cylinder. In this study, we apply a series of saw-tooth-shaped grooves on the piston surface, and numerically investigate the effects of groove depth, groove angle, and the number of grooves with radial clearance variations using a finite difference method. We conduct a dynamic analysis of the piston for various changes in groove geometries to obtain the minimum radial clearance variation for the entire compression cycle. The minimum radial clearance increases while friction loss decreases when we apply the series of saw-tooth-shaped grooves on the piston. In addition, we analyze the impact of the change in the groove shape variable due to changes in radial clearance. Leakage variations are relevant to radial clearance, but have almost no effect on the groove parameters.

• 한국기후변화학회지
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• 제8권2호
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• pp.109-123
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• 2017

The effects of recent climate change on hydrological systems could affect the Winter Olympic Games (WOG) because the event is dependent on suitable snow and ice conditions to support elite-level competitions. We investigate the long-term variability and change in winter total precipitation (P), snowfall water equivalent (SFE), and ratios of SFE to P during the period 1973/74~2015/16 in Gangwon province. The climatological percentages of SFE relative to winter total precipitation were 71%, 28%, and 44% in Daegwallyeong, Chuncheon, and Gangneung, respectively. The winter total P, SFE, and SFE/P has decreased (but not significantly), although significant increases of winter maximum and minimum temperature were detected at a 95% confidence level. Notably, a significant negative trend of SFE/P at Daegwallyeong in February, the month of the WOG, was attributable to a larger decrease in SFE related to the increases in maximum and minimum temperature. Winter wet-day minimum temperatures were warmer than climatological minimum temperatures averaged over the study period. The 20-year return values of daily maximum P and SFE decreased in Yongdong area. Since the SFE/P decrease with increasing temperature, the probability of rainfall rather than snowfall can increase if global warming continues.

• 한국사회복지학
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• 제38권
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• pp.7-32
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• 1999

현재의 생활보호제도는 거택 및 시설보호대상자의 선정기준이 지나치게 낮아 생계 보조를 필요로 하는 많은 집단이 보호대상에 포함되지 못하고 있으며, 급여수준도 최저생계비를 충족시켜 주지 못하는 수준이다. 뿐만 아니라, 전국에 동일한 대상자 선정기준 및 급여수준을 일률적으로 적용하고 있어 지역간물가, 특히 주거비 편차에 따른 최저생계비 차이가 반영되지 못하고 있다. 이 연구는 현재의 생활보호사업이 지역간 편차 및 최저생계비를 충족시키지 못하고 있다는 점에 논의의 초점을 두고, 서울시를 연구대상으로 지역 최저생계비를 계측하였다. 계측된 서울시 최저생계비를 전국기준과 비교함으로써 지역간 편차를 규명하였으며, 현재의 생활보호사업으로부터 보호받지 못하는 실질적인 빈곤인구 규모를 파악하였다. 생활보호사업에서 이용하고 있는 전국기준과의 비교를 위하여 현재 대상자 선정기준 및 급여수준 결정의 근간이 된 1994년 한국보건사회연구원의 <최저생계비 계측조사연구>에서 사용한 데이터 및 계측방법을 이용하여 1994년 서울시 최저생계비를 계측하였다. 계측결과 1994년 서울시 4인 표준가구의 최저생계비는 88만 7,611원으로, 이는 보사연에서 계측한 전국평군 최저생계비보다 약 1.33배 높은 값이다. 이를 빈곤선으로 간주하고 1994년도 도시가계조사데이터 서울시 표본을 이용하여 빈곤인구를 추정한 결과, 서울시 인구의 약 5.9%인 63만 6천여명이 이 기준에 미치지 못하는 것으로 나타났다. 이는 1994년 서울시 생활보호대상자 12만 3천명의 약 5.2배에 이르는 수치이다.