• ETRI Journal
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• 제40권1호
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• pp.51-60
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• 2018

In Long Term Evolution (LTE) cellular networks, the transmit power control (TPC) mechanism consists of two parts: the open loop (OL) and closed loop. Most cellular networks consider OL/TPC because of its simple implementation and low operation cost. The analysis of OL/TPC parameters is essential for efficient resource management from the cellular operator's viewpoint. In this work, the impact of the OL/TPC parameters is investigated for homogeneous small cells and heterogeneous small-cell/macrocell network environments. A mathematical model is derived to compute the transmit power at the user equipment, the received power at the eNodeB, the interference in the network, and the received signal-to-interference ratio. Using the analytical platform, the effects of the OL/TPC parameters on the system performance in LTE networks are investigated. Numerical results show that, in order to achieve the best performance, it is appropriate to choose ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in a homogenous small-cell network. Further, the selections of ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in the small cells and ${\alpha}_{macro}=0.8$ and $P_{o-macro}=-100dBm$ in the macrocells seem to be suitable for heterogeneous network deployment.

• 전기전자학회논문지
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• 제20권3호
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• pp.260-264
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• 2016

MAX77846은 MAX77826과 호환해서 최신 웨어러블 시계와 3G/4G 스마트폰용의 전력모듈(PMIC)로 사용된다. MAX77846은 주변장치의 전력을 공급하기 위해 N 채널 MOSFET와 고효율의 레귤레이터, 비교기 등으로 구성되어 있다. 또한, 완전한 적용성과 각각의 레귤레이터 출력전압을 제공하기 위해 $I^2C$ 연산을 위해 전력 on/off 제어 로직을 제공한다. 이 논문에서 MAX77846을 기반으로 한 축약된 전력 매크로 모델을 전류와 시간에 대한 배터리 전압의 상태를 검증하기 위해 설계하고 LTspice로 시뮬레이션을 수행한다. Samsung Galaxy Gear 2 용 충전된 배터리 용량이 실시간으로 주요기능을 수행하는데 흐르는 전류를 측정한 후 특정한 기능을 수행하는데 사용가능한 시간을 검증하여 차세대 전력 모듈의 설계변수로 활용하는데 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권9호
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• pp.1596-1612
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• 2011

Coordinated Multi-Point (CoMP) transmission / reception is being studied in Long Term Evolution-Advanced (LTE-A) for future evolution of the $3^{rd}$ Generation Partnership Project (3GPP) LTE. Support of soft handover is essential for improving the performance of cell edge users. CoMP provides a natural framework for enabling soft handover in the LTE system. This paper evaluates the soft handover gain in LTE-A downlink. Mathematical analysis of signal to interference plus noise ratio (SINR) gain and the handover margins for soft handover and hard handover are derived. CoMP system model is developed and an inter-cell and intra-cell interference model is derived, taking into account the pathloss, shadowing, cell loading, and traffic activity. Reference signal received power (RSRP) is used to define the triggers and the measurements for soft handover. Our results indicate that parameter choices such as handover margin and the CoMP set size impact CoMP performance gain.

• 동력기계공학회지
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• 제19권3호
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• pp.55-62
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• 2015

This paper discusses a new model for investigating the micro-mechanical behavior of beam-like structures composed of various elastic moduli and complex geometries varying through the cross-sectional directions and also periodically-repeated along the axial directions. The original three-dimensional problem is first formulated in an unified and compact intrinsic form using the concept of decomposition of the rotation tensor. Taking advantage of two smallness of the cross-sectional dimension-to-length parameter and the micro-to-macro heterogeneity and performing homogenization along dimensional reduction simultaneously, the variational asymptotic method is used to rigorously construct an effective zeroth-order beam model, which is similar a generalized Timoshenko one (the first-order shear deformation model) capable of capturing the transverse shear deformations, but still carries out the zeroth-order approximation which can maximize simplicity and promote efficiency. Two examples available in literature are used to demonstrate the consistence and efficiency of this new model, especially for the structures, in which the effects of transverse shear deformations are significant.

• 한국산학기술학회논문지
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• 제21권5호
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• pp.458-465
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• 2020

본 연구의 목적은 제주지역 거시경제 전망모형을 이용하여 제주지역 사회의 중요한 정책에 대한 효과분석을 수행하는 것이다. 이를 위해, 본 연구에서는 기존의 Ko, et al.(2012) 모형을 본 연구의 목적에 맞게 확대·개편하였다. 연구의 주요 결과를 요약하면 다음과 같다. 첫째, 정책효과 분석을 위해, 2017년까지의 관련 통계자료와 데이터베이스를 갱신·점검하고, 새로운 대내외 정책변수들과 모듈(module)을 확대·추가함으로써 모형의 현실 설명력을 향상시켰다. 그리고 제주경제의 산업구조 변화에 따라 모형에서 설정된 산업구조를 보다 세분화시켰으며, 특히 케인즈 이론의 수요측면까지 모형에서 동시에 고려할 수 있도록 모형의 구조를 확장시켰다. 둘째, 모형의 평가에서는 구(舊)모형에 비해 본 연구의 모형에 대한 예측력이 우수한 것으로 평가되었다. 다만, 일부 내생변수에서 향후 지속적인 자료의 보완을 통해 보다 개선된 모형 개발의 시사점을 얻을 수 있었다. 셋째, 제2공항 건설에 따른 정책효과 분석결과, GRDP 1.25배, 고용 1.2배, 민간소비 1.48배, 투자 2.06배 증대되는 효과를 보이는 것으로 분석되었다. 그리고 경제성장률은 제2공항을 건설할 경우가 그렇지 않을 때보다 연평균 1.6%p 높은 것으로 분석되었다. 마지막으로 본 연구의 결과는 제주특별자치도의 정책의 사결정에 있어 직·간접적으로 활용될 수 있을 것으로 기대된다.

• 한국전자파학회논문지
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• 제25권7호
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• pp.757-766
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• 2014

본 논문은 거시적인 접근방법을 이용하여 고출력 전자기파에 대한 피해 비용을 보다 실제적으로 산출하기 위한 방법을 제시하고, 이에 대한 피해액을 계산하였다. 먼저 취약성 분석을 통하여 사회 기반 시설 중 사회적으로 가장 큰 혼란을 야기할 수 있을 것이라고 판단되는 전력망에 집중하여 연구하였으며, 이에 대해 고출력 전자기파에 의한 피해액 계산식은 GDP에 대한 총 에너지 소비를 고려하여 고출력 전자기파 피해 시 발생할 수 있는 피해 손실을 효과적으로 예측하기 위한 방법을 제시하였다. 피해액은 고출력 전자기파의 공격 형태에 따라 피해 범위를 설정하고 계산하였으며, 이러한 피해액 계산을 통하여 고출력 전자기파에 취약한 시설에 대해서는 피해액 산출 후 방호 비용과 비교하여 시설 방호 대책을 수립할 수 있는 기반을 마련할 수 있을 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.275-278
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• 2006

This paper describes a probabilistic annual congestion cost assessment of a grid at a composite power system derived from a model. This probabilistic congestion cost assessment simulation model includes capacity limitation and uncertainties of the generators and transmission lines. In this paper, the proposed probabilistic congestion cost assessment model is focused on an annualized simulation methodology for solving long-term grid expansion planning issues. It emphasizes the questions of "how should the uncertainties of system elements (generators, lines and transformers, etc.) be considered for annual congestion cost assessment from the macro economic view point"? This simulation methodology comes essentially from a probabilistic production cost simulation model of composite power systems. This type of model comes from a nodal equivalent load duration curve based on a new effective load model at load points. The characteristics and effectiveness of this new simulation model are illustrated by several case studies of a test system.

• 한국시스템다이내믹스연구
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• 제6권1호
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• pp.99-123
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• 2005

Although the generation market is competitive, the power market is easily exercised the market power by one generator due to its special futures such as a limited supplier, large investment cost, transmission constraints and loss. Specially, as Korea Electric industry restructuring is similar US competitive wholesale electricity market structure which discovered the several evidences of market power abuse, when restructuring is completed the possibility that market power will be exercised is big. Market power interferes with market competitions and efficiency of system. The goal of this study is to investigate the market price effects of the potential market power and the proposed market power mitigation strategy in Korean market using the forecasting wholesale electricity market model. This modeling is developed based on the system dynamics approach. it can analyze the dynamic behaviors of wholesale prices in Korean market. And then it is expanded to include the effect of market condition changed by 'strategic behavior' and 'real time pricing.' This model can generate the overall insights regarding the dynamic impact of output withholding by old gas fire power plant bon as a marginal plant in Korean market at the macro level. Also it will give the energy planner the opportunity to create different scenarios for the future for deregulated wholesales market in Korea.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.155-157
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• 2001

This paper presents an comparative study on the effect of SSSC and UPFC to the power system static analysis. SSSC is used to control active power flow in transmission lines by controlling the phase angle of the injected voltage source which is in rectangular to the line current. UPFC is used to control the magnitude and phase of the injected voltage sources which are connected both in series and in parallel with the transmission line to control power flow and bus voltage. To compare the effect of SSSC and UPFC in power system static analysis, the PSS/E simulation program is used. As the FACTS device model such as SSSC and UPFC is not provided in PSS/E yet, an equivalent load model is used. This procedure is implemented by IPLAN which is an external macro program of PSS/E. The simulation results show that UPFC is more effective to improve bus voltage than SSSC in power system static analysis.

• 보건행정학회지
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• 제9권1호
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• pp.156-177
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• 1999

The current method of rate adjustment for inflation is based on the evaluation of the financial performance of hospitals. The method has the disadvantage such as too complicated, expensive process as well as low reliability. This study, therefore, develops the 'Korean Medical Insurance Economic Index(MIEI)' as a new model for the rate adjustment with the use of the macro economic indices. In addition, we calculate the 1992∼1998 rate adjustment with the MIEI, and examines the validity of the MIEI by comparing with the conventional method. Medical costs are classified into nine categories : physician salaries, nurse·pharmacist·medical technician salaries, assistants & others salaries, material cost(by imports), material cost(by domestics), depreciation & rent paid(by imports), depreciation & rent paid(by domestics), power utilities, other administrative costs. Then the category weight which is the ratio of category in the total cost is calculated. Macro economic indices are selected for each cost category in order to reflect the concept of the each cost category and inflation during the year of 1992∼1998. Finally MIEI which integrate all category according to the category weight and selected macro indices is calculated. The mean of hospital MIEI which weighting by amount paid by insurers was cacluated. The result from the application of empirical data to the MIEI model is very similar to that of the current method. Furthermore, this method is very simple and also easy to get social consensus. This MIEI model can be replaced the current method based on the analysis of the financial performance for the adjustment of medical fees.