• 한국시뮬레이션학회논문지
• /
• 제9권3호
• /
• pp.91-102
• /
• 2000

The distribution routing problem is one of the important problems in distribution and supply center management. This research is concerned with an integrated distribution routing problem for multi-supply centers based on improved genetic algorithm and GUI-type programming. In this research, we used a three-step approach; in step 1 a sector clustering model is developed to transfer the multi-supply center problem to single supply center problems which are more easy to be solved, in step 2 we developed a vehicle routing model with time and vehicle capacity constraints and in step 3, we developed a GA-TSP model which can improve the vehicle routing schedules by simulation. For the computational purpose, we developed a GUI-type computer program according to the proposed methods and the sample outputs show that the proposed method is very effective on a set of standard test problems, and it could be potentially useful in solving the distribution routing problems in multi-supply center problem.

• Journal of Power Electronics
• /
• 제17권2호
• /
• pp.522-532
• /
• 2017

This paper presents a novel integrated structure for a cascaded distribution static compensator (D-STATCOM) and distribution transformer for medium-voltage reactive power compensation. The cascaded multilevel converter is connected to a system via a group of special designed taps on the primary windings of the Dyn11 connection distribution transformer. The three-phase winding taps are symmetrically arranged and the connection point voltage can be decreased to half of the line-to-line voltage at most. Thus, the voltage stress for the D-STATCOM is reduced and a compromise between the voltage rating and the current rating can be achieved. The spare capacity of the distribution transformer can also be fully used. The working mechanism is explained in detail and a modified control strategy is proposed for reactive power compensation. Finally, both simulation and scaled-down prototype experimental results are provided to verify the feasibility and effectiveness of the proposed connection structure and control strategy.

• 대한한의학회지
• /
• 제31권5호
• /
• pp.82-89
• /
• 2010

Objectives: The aim of this study was to determine distribution patterns of TOAST subtypes of ischemic stroke patients admitted to oriental hospitals and to get a better understanding of present conditions in oriental medicine by comparing with the Korea stroke registry (KSR), the largest and representative data. Methods: Clinical data were collected from acute ischemic stoke patients. MRI studies including vascular images were performed in all cases. TOAST criteria were used to determine subtypes of ischemic stroke patients. According to the duration from disease onset to hospital admission time, patients were assigned to 3 groups (Group I0 to 3 d, Group II4 to 7 d, Group III8 to 28 d) and the distribution of TOAST subtypes were compared among these three groups. Results: We collected 514 sets of clinical data from 10 oriental hospitals between May 2007 and September 2009. Small vessel occlusion (SVO) subtype was the most common (57.62%), followed by large artery atherosclerosis (LAA, 29.98%). Compared with TOAST distribution of KSR, the proportion of ischemic stroke patients with SVO subtype was higher than that of KSR. On the other hand the proportion of patients with stroke of undetermined etiology (SUE) was lower. Distributions of SVO, LAA and cardioembolism (CE) in group were I 66.4%, 23.8% and 8.9%, respectively; those in group IIIwere 51.03%, 34.71% and 11.57%, respectively. Conclusions: In oriental hospitals, the proportion of ischemic stroke patients diagnosed as SVO type was higher than that of KSR. At early stage (from onset to 2 d) proportion of SVO was very high, however after 7 days from onset it decreased with concomitant increases in proportions of LAA and CE. These phenomena may be due to the facts that 1) at early stage emergency treatments are limited in oriental hospitals, 2) after early stage many patients prefer oriental treatments, including rehabilitation.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
• /
• pp.205-210
• /
• 2002

This article presents an integrated modeling approach for coupled analysis of heat transfer and microstructure evolution in welding carbon steel. The modeling procedure utilizes commercial [mite element code ABAQUS/Standard as the platform for solving the equation of heat conduction. User subroutines that implement computational thermodynamics and kinetics models are integrated with the FEA code to compute the transient microstructure evolution. In this study, the integrated models are applied to simulate the hot-tap repair welding of carbon steel pipeline. Microstructural components are treated as user output variables. Based on the predicted microstructure and cooling rates, hardness distributions in the welds were also predicted. The predicted microstructure and hardness distribution were found in good agreement with metallographic examinations and hardness measurements. This study demonstrates the applicability of computational models for the development of welding procedure for in-service pipeline repair.

• Journal of the Optical Society of Korea
• /
• 제18권5호
• /
• pp.466-471
• /
• 2014

An asynchronous optical packet-switching (AOPS) node with load-balancing capability can achieve better performance in reducing the high packet-loss ratio (PLR) and time delay caused by unbalanced traffic. This paper proposes a novel dynamic load-balancing algorithm for an AOPS node with limited buffer and without wavelength converters, and considering the data flow distribution and service levels. By calculating the occupancy state of the output ports, load state of the input ports, and priorities for data flow, the traffic is balanced accordingly. Simulations demonstrate that asynchronous variant data packets and output traffic can be automatically balanced according to service levels and the data flow distribution. A PLR of less than 0.01% can be achieved, as well as an average time delay of less than 0.46 ns.

• International Journal of Korean Welding Society
• /
• 제2권2호
• /
• pp.1-6
• /
• 2002

This article presents an integrated modeling approach for coupled analysis of heat transfer and microstructure evolution in welding carbon steel. The modeling procedure utilizes commercial finite element code ABAQUS/Standard as the platform for solving the equation of heat conduction. User subroutines that Implement computational thermodynamics and kinetics models are integrated with the FEA code to compute the transient microstructure evolution. In this study, the integrated models are applied to simulate the hot-tap repair welding of carbon steel pipeline. Microstructural components are treated as user output variables. Based on the predicted microstructure and cooling rates, hardness distributions in the welds were also predicted. The predicted microstructure and hardness distribution were found in good agreement with metallographic examinations and hardness measurements. This study demonstrates the applicability of computational models for the development of welding procedure for in-service pipeline repair.

• 한국IT서비스학회지
• /
• 제12권3호
• /
• pp.1-21
• /
• 2013

This study attempts to explain the mechanism behind the migration from vertically integrated value chain architecture to an innovation ecosystem consisting of horizontally separated layers in value chain. We first present a comprehensive framework based on the theoretical analysis of the drivers for migration to an innovation ecosystem, which are standard (institution), capability distribution, and transaction costs. The theoretical framework suggests that the migration to an innovation ecosystem is explained by the influence of standard on the evolutionary change of capability distribution and transaction costs. In particular, when the new de-jure standard competes with the de-facto standard, the new de-jure standard has the greatest impact on the distribution capabilities and the transaction costs. Based on this theoretical framework, we analyze the latest SDN (Software Defined Networking) case of the network industry. SDN standard has transformed the industry from a vertically integrated value chain architecture to a horizontally separated one with its influence on the distribution capabilities and the transaction costs in the industry.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2016년도 춘계학술대회
• /
• pp.617-620
• /
• 2016

국내 농산물 유통분야는 농산물의 유통효율성 제고와 수급 및 가격의 불안정 문제를 해결하기 위해서는 기존의 농산물 유통 단계별 주체별 기능별로 개별적이고 독립적인 유통 및 물류관리 체계의 한계를 극복하고 전체 공급 사슬의 참여주체 간 상품 물류 정보 자금흐름 등에서 통합 연계 협력체계를 바탕으로 수급안정과 물류효율성 제고를 실현할 수 있는 방안 제시가 필요하다. 따라서 본고는 이러한 방안제시의 일환으로 농산물 유통 프로세스 상의 정보 관리 현황과 문제점을 살펴보고, 이를 기반으로 농산물 유통 정보를 통합 연계 체계를 구축할 수 있는 농산물 통합유통정보시스템 구조에 대한 참조 표준 모델 및 정보 구조의 표준화 방안을 제시하고자 한다.

• 대한기계학회논문집A
• /
• 제40권12호
• /
• pp.997-1003
• /
• 2016

본 논문은 자세 제어 장치와 능동 후륜 조향장치를 가지는 통합 섀시 제어에서 요 모멘트 분배를 위해 적응 알고리즘을 적용하는 방법을 제안한다. 통합 섀시 제어는 상위제어기와 하위제어기로 구성된다. 상위제어기에서 슬라이딩 모드 제어 이론을 이용하여 차량을 안정화시키는데 필요한 제어 요 모멘트를 계산한다. 하위제어기에서는 제어 요 모멘트를 만들어 내기 위해 자세 제어 장치의 제동 압력과 능동 후륜 조향장치의 조향각을 결정하는 데에 적응 알고리즘을 적용한다. 차량 시뮬레이션 패키지인 CarSim에서 시뮬레이션을 수행하여 제안된 방법의 타당성을 검증한다.

• Macromolecular Research
• /
• 제11권5호
• /
• pp.341-346
• /
• 2003

A poly(ethylene oxide)-b-poly(L-lactide) diblock copolymer (PEO-b-PLLA) is characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and a block length distribution map is constructed. Although the MALDI- TOF mass spectrum of PEO-b-PLLA is very complicated, most of the polymer species were identified by isolating the overlapped isotope patterns and by fitting the overlapped peaks to the Schulz-Zimm distribution function. Reconstructed MALDI-TOF MS spectrum was nearly identical to the measured spectrum and this method shows its potential to be developed as an easy and fast analysis method of low molecular weight block copolymers.