• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.6-11
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• 2001

본 논문에서는 서로 다른 공간해 상도를 갖는 두계층 영상부호화대서 하위계층에는 낮은 우선순위로 인하여 제한된 일정부호화율로 부호화하고, 반면에 각 영상의 상위계층에는 우선순위를 높게 하면서 서로간 균등한 화질을 제공하는 대역할당 방법을 제안한다. 이를 위해서 MPEG-2 공간계층적 부호화구조에서 부호화율-왜곡의 관계를 찾고, 실시간으로 상위계층 영상 사이에 균등한 화필을 제공하는 부호화율 제어방법을 제안한다.

• The Korean Journal of Applied Statistics
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• v.28 no.6
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• pp.1047-1061
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• 2015

Stratified random sampling is a powerful sampling strategy to reduce variance of the estimators by incorporating useful auxiliary information to stratify the population. Sample allocation is the one of the important decisions in selecting a stratified random sample. There are two common methods, the proportional allocation and Neyman allocation if we could assume data collection cost for different observation units equal. Theoretically, Neyman allocation considering the size and standard deviation of each stratum, is known to be more effective than proportional allocation which incorporates only stratum size information. However, if the information on the standard deviation is inaccurate, the performance of Neyman allocation is in doubt. It has been pointed out that Neyman allocation is not suitable for multi-purpose sample survey that requires the estimation of several characteristics. In addition to sampling error, non-response error is another factor to evaluate sampling strategy that affects the statistical precision of the estimator. We propose new sample allocation methods using the available information about stratum response rates at the designing stage to improve stratified random sampling. The proposed methods are efficient when response rates differ considerably among strata. In particular, the method using population sizes and response rates improves the Neyman allocation in multi-purpose sample survey.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.1
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• pp.15-21
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• 2006

This study was conducted to understand the regulation mechanism of carbohydrate allocation and partitioning of one-year-old seedlings of Betula schmidtii with Cd treatment, and to assess tolerance against Cd toxicity among five half-sib families on the basis of carbon allocation and partitioning. Seedlings were treated with $CdSO_4$ solution of 0, 0.2, 0.4, and 0.6 mM for two months. After harvesting, carbohydrate concentrations were analyzed for leaves, stems and roots of seedlings. Carbohydrate concentration for Cd-treated seedlings decreased in comparison with control plants, even though Cd effects were significantly different among five families. Meanwhile, Cd treatment decreased carbohydrate allocation in leaves and increased allocation in roots. In addition, partitioning of glucose in leaves was increased by Cd treatment, but partitioning of sucrose and starch in leaves decreased. In Cd-treated roots, partitioning of glucose, sucrose and starch increased. On the basis of carbohydrate allocation patterns, 'Family No. 7' (of the five families studied) was considered as the most sensitive family to Cd toxicity because the decrease of carbohydrate concentration and the change of carbohydrate allocation pattern after Cd treatment were relatively greater.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.328-333
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• 1990

In developing dynamic growth model of a crop, it is important to estimate accurate dry matter partition to different parts of crop plants. Two rice varieties, Samkang and Chucheong, were transnplanted with three planting densities of 72. 90 and 120 hills per 3.3㎡ on May 30 and June 15 in 1988 to study the effect of planting density on dry matter partition in rice plants. Total dry wight per square meter of two varieteis in May 30 transplanting were greater than those in June 15 transplanting. Total dry wights were increased as planting density was increased. The response of dry weights of differents parts of rice plants per hill were decreased as the density was increased. Although the difference in dry weights of leaf blade and stem and sheath between two varieties was not great, greater ear weight of Samkang resulted in greater total dry weight than that of Chucheong. Despite of transplant in date and planting density on dry weights, the ratio of dry matter partition to different parts of rice plants at a certain growth stage remained constant. Estimated dry weights of different parts at two stages of growth based on average ratio of dry matter partition over two transplantion dates and planting densities agreed well with those observed.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.123-133
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• 2008

Information collection systems and applications in a ubiquitous environment has emerged as a leading issue in transportation and logistics. A productive application example is a traffic information collection system based on probe vehicles and wireless communication technology. Estimation of hourly OD pairs using probe OD data is a possible target. Since probe OD data consists of sample OD pairs, which vary over time and space, computation of sample rates of OD pairs and expansion of sample OD pairs into static OD pairs is required. In this paper, the authors proposed a method to estimate sample OD data with probe data in Jeju City and expand those into static OD data. Mean absolute percentage difference (MAPD) error between observed traffic volume and assigned traffic volume was about 22.9%. After removing abnormal data, MAPD error improved to 17.6%. Development of static OD estimation methods using probe vehicle data in a real environment is considered the main contribution of this paper.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.2049-2053
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• 2007

KModSim은 수자원배분에 관련된 물리적, 수문학적, 제도적, 그리고 행정적인 요구들을 동시에 만족하도록 디자인된 범용 우선순위 목적 선형최적화 모형으로써 자연유3tt입량과 기득 수리권 혹은 기득 저류권 등과 같은 다양한 형태의 저수권 사이의 조화운영이 가능하다. KModSim은 목적함수에 관련된 제약조건의 유연한 설정과 변경이 가능하며, 기존의 최적화 방법과 다르게 유역통합모의에 관련한 모형변수가 모형내에서 자동적으로 생성되도록 프로그램화 되어있다. 본 연구에서는 금강유역내 수자원의 효율적인 운영을 위하여 과거운영자료를 토대로 저수지운영율을 개발하고 시스템단계(system states)를 이용하여 KModSim 네트워크에 운영율을 적용하였다. 금강유역에서 개발한 운영율을 적용하고 모의한 결과 개발된 운영율은 실제저류량을 잘 재현하는 것으로 나타났다. 본 연구에서 개발된 운영율 및 시스템단계 방법은 다중목적 우선순위 선형최적화 모형을 이용하여 유역의 다양한 수자원운영모의에 사용될 수 있을 것으로 기대된다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.22-24
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• 2004

최근 무선통신 기술의 발전으로 PC뿐만 아니라 PDA, 휴대폰 등 다양한 장치를 통하여 멀티미디어 서비스를 제공받을 수 있게 되었다. 무선망은 유선망에 비해 대역폭이 낮기 때문에 높은 비트율을 갖는 스트림을 낮은 비트율로 변환하기 위해 트랜스코딩을 이용한다. 따라서 이러한 트랜스 코딩 시스템에서 효율적으로 무선 스트리밍을 전송하기 위해서는 부하 분산에 관한 연구가 필요하다 본 논문에서 제안한 클러스터 트랜스코딩 시스템은 스트리밍 서비스의 모바일 호스트 등급에 따른 CPU 사용량, 네트워크 대역폭, 메모리의 가중치를 계산하여 부하배분에 사용할 수 있는 부하분산 모델을 제시하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.355-357
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• 2004

최근 무선통신기술의 발전으로 PC뿐만 아니라 PDA, 휴대폰 등 다양한 장치를 통하여 멀티미디어 서비스를 제공받을 수 있게 되었다. 무선망은 유선망에 비해 대역폭이 낮기 때문에 높은 비트율을 갖는 스트림을 낮은 비트율로 변환하기 위해 트랜스코딩을 이용한다. 따라서 이러한 트랜스코딩 시스템에서 효율적으로 무선 스트리밍을 전송하기 위해서는 부하분산에 관한 연구가 필요하다 본 논문에서 제안한 클러스터 트랜스코딩 시스템은 스트리밍 서비스의 모바일 호스트 등급에 따른 CPU 사용량, 네트워크 대역폭, 메모리의 가중치를 계산하여 부하 배분에 사용할 수 있는 부하 분산 모델을 제시한다.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.1
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• pp.1-6
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• 2004

This paper suggests an extended power flow analysis algorithm based on a modified economic load dispatch concept. Meaningfully, the proposed method makes it possible to perform the power flow analysis without a slack bus. And the 'equal incremental cost' rule which is obtained by economic load dispatch prior to power flow is maintained even during the proposed power flow analysis. In this paper, both 5 - bus and 14 - bus power systems are used to offer the theoretical accuracy and practical applications of this algorithm.

• Journal of the Korea Society for Simulation
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• v.32 no.4
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• pp.69-76
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• 2023

To improve the financial stability of the National Pension, an appropriate target rate of return should be established based on pension liabilities, and asset allocation policies should be formulated accordingly. The purpose of this study is to calculate the target rate of return considering the contributions of subscribers and the pension benefits, and based on this, derive an asset allocation. To do this, we utilized the internal rate of return methodology to calculate the target rate of return for each cohort. And then, we employed a Monte Carlo simulation-based re-sampling mean-variance model to derive asset allocation for each cohort that satisfy the target rate of return while minimizing risks. Our result shows that the target rate of return for each cohort ranged from 6.4% to 6.85%, and it decreased as the generations advanced due to a decrease in the income replacement rate of the National Pension. Consequently, the allocation of risky assets, such as stocks, was relatively reduced in the portfolios of future generations. This study holds significance in that it departs from the macroeconomic-based asset allocation methodology and proposes investments from an asset-liability management perspective, which considers the characteristics of subscribers' liabilities.