• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.601-612
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• 2005

In mountainous area, Two parallel tunnels have been usually recognized as a road tunnel which has benefits in aspects of cost and stability. However, Design and construction of 2-Arch road tunnel are growing recently due to environmental destruction, compensation of land and difficulty of route separation. As studies are mainly undergoing on only guaranteeing stability and developing a waterproofing-drainage system to avoid water leakage through comprehension for characteristics of 2-arch tunnel behaviors, there is a tendency to evaluate quantity of support by empirical method with a tunnel which has a complicated cross-section and lack of construction ability. In this study, therefore, we made a plan of tunnel cross-section which had shown good construction ability and developed the waterproofing-drainage system which is able to solve the water leakage problem fundamentally by analyzing precedented 2-arch tunnels and investigating their sites in and out of nation. We also determined fixed quantity of support by a large-scale model test and numerical analysis. We want to contribute to 2-arch tunnel design hereafter introducing design procedure and method applied here.

• 한국경영과학회지
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• 제40권3호
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• pp.1-21
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• 2015

Customer firms exercise various sources of power to influence their suppliers' behaviors or decisions. In this study we aim to examine the effects of customers' sources of power on their supplier's performance improvement. This study posits that a customer's expert, referent, and reward power positively influence a supplier's performance directly as well as indirectly through increased supplier-customer integration. On the contrary, the customer's coercive power is expected to worsen the supplier's operational performance because of increasing distrust, dissatisfaction, and conflict with the customer. Data collected from 1,229 firms from Korea, China, Hong Kong, Taiwan, and the U.S. are used to test the hypotheses. Expert power proves to be the most effective source of customer power in improving a supplier's inventory cost, delivery, and flexibility performance. In contrast, coercive power deteriorates significantly all supplier performance variables. Academic and managerial implications are presented and future research directions are also discussed.

• Structural Monitoring and Maintenance
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• 제5권1호
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• pp.39-50
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• 2018

Taking three types of bridge bearings with diameter being 100 mm as examples, the theoretical analysis, the experimental research as well as the numerical simulation of these bearings is conducted. Since the normal compression and shear machines cannot be applied to the small-size bearings, an improved equipment to test the properties of these bearings is proposed and fabricated. Besides, the simulation of the bearings is conducted based on the explicit finite element software ANSYS/LS-DYNA, and some parameters of the bearings are modified in the finite element model to reduce the computation cost effectively. Results show that all the research methods are capable of revealing the fundamental properties of the small-size bearings, and a combined use of these methods can better catch both the integral properties and the inner detailed mechanical behaviors of the bearings.

• Structural Engineering and Mechanics
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• 제34권4호
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• pp.525-539
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• 2010

Polymer matrix composites are widely used in many engineering applications as they can be customized to meet a desired performance while not only maintaining low cost but also reducing weight. Polymers can experience viscoelastic-viscoplastic response when subjected to external loadings. Various reinforcements and fillers are added to polymers which bring out more complexity in analyzing the timedependent response. This study formulates an integrated micromechanical model and finite element (FE) analysis for predicting effective viscoelastic-viscoplastic response of polymer based hybrid composites. The studied hybrid system consists of unidirectional short-fiber reinforcements and a matrix system which is composed of solid spherical particle fillers dispersed in a homogeneous polymer constituent. The goal is to predict effective performance of hybrid systems having different compositions and properties of the fiber, particle, and matrix constituents. A combined Schapery's viscoelastic integral model and Valanis's endochronic viscoplastic model is used for the polymer constituent. The particle and fiber constituents are assumed linear elastic. A previously developed micromechanical model of particle reinforced composite is first used to obtain effective mechanical properties of the matrix systems. The effective properties of the matrix are then integrated to a unit-cell model of short-fiber reinforced composites, which is generated using the FE. The effective properties of the matrix are implemented using a user material subroutine in the FE framework. Limited experimental data and analytical solutions available in the literatures are used for comparisons.

• 한국콘텐츠학회논문지
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• 제9권2호
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• pp.462-470
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• 2009

학습 공간의 확대로 원격교육은 교수 학습 방법의 주요 흐름의 하나로서 자리잡았고 이를 지원하기 위한 다양한 매체, 기술 및 전략 등에 관한 연구가 지속적으로 이루어지고 있다. 하지만 대부분의 원격교육시스템은 교수자나 학습자에게 일정 수준 이상의 기술적 소양과 경제적 부담을 요구한다. 또한 이러한 문제점을 해소하기 위한 학교 현장에서의 간소화된 웹 기반 원격교육시스템은 학습자 행동을 파악하기 어렵게 하는 단점이 있다. 이에 본 연구에서는 시스템의 구축 및 운영에 필요한 부담을 제거하고 원격학습 환경에서 학습자의 지식 상태에 의존하여 개별화 학습이 가능한 개별적 발문에 기반한 동적 원격교육시스템을 개발하고 그 효과성을 검증하였다.

• 한국산학기술학회논문지
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• 제8권2호
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• pp.333-338
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• 2007

내부 구속 중공 RC 교각은 교각의 강성 및 연성의 증가를 목적으로, 중공 RC 교각의 중공 면에 내부 구속력을 제공하는 강관을 삽입한 교각이다. 본 연구에서는 내부 강관의 두께를 변화시켜 내부 구속 중공 RC 교각의 거동 특성을 파악하였으며, 거동 특성을 파악하기 위한 평가 방법으로는 안전율, 연성능력, 재료비, 교각의 총중량 등으로 평가하였다. 해석적 연구 결과, 내부 구속 중공 RC 교각의 내부 강관 두께는 최소 필요 두에를 적용하는 것이 가장 효과적인 것으로 나타났다. 또한, 중공 단면에 대한 교각의 자중감소 효과를 확인할 수 있었다.

• Asian Journal of Business Environment
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• 제10권1호
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• pp.19-28
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• 2020

Purpose: This research aims to investigate the impact of corporate integrity on stock price crash risk. Research design, data, and methodology: Taking 1419 firms listed in Shenzhen Stock Exchange in China as a sample, this paper empirically analyzed the relationship between corporate integrity and stock price crash risk. The main integrity data was hand-collected from Shenzhen Stock Exchange Website. Other financial data was collected from CSMAR Database. Results: Findings show that corporate integrity can significantly decrease stock price crash risk. After changing the selection of samples, model estimation methods and the proxy variable of stock price crash risk, the conclusion is still valid. Further research shows that the relationship between corporate integrity and stock price crash risk is only found in firms with weak internal control and firms in poor legal system areas. Conclusions: Results of the study suggest that corporate integrity has a significant influence on behaviors of managers. Business ethics reduces the likelihood of managers to overstate financial performance and hide bad news, which leads to the low likelihood of future stock price crashes. Meanwhile, corporate integrity can supplement internal control and legal system in decreasing stock price crash risks.

• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.416-424
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• 2005

At present, the Korean electricity industry is undergoing restructuring and the Cost Based-generation Pool (CBP) market is being operated in preparation of a Two Way Bidding Pool (TWBP) market. In deregulated electricity industries, an integrated power market simulator is one of the tools that can be used by market participants and market operators analyzing market behaviors and studying market structures and market codes. In this regard, it is very important to develop an electricity market simulator that reflects market code providing a market operation mechanism. This paper presents the development of an integrated market simulator, called the Power Exchange Simulator (PEXSIM), which is designed to imitate the Korean electricity market considering the various features of the market operating mechanism such as uniform price and constrained on/off payment. The PEXSIM is developed in VB.NET and composed of five modules whose titles are M-SIM, P-SIM, O-SIM, T-SIM and G-SIM interfacing the Access database program. To verify the features and the performance of the PEXSIM, a small Two Way bidding market with a 12-bus system and a One Way bidding market for generator competition will be presented for the electricity market simulations using PEXSIM.

• 한국강구조학회 논문집
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• 제15권4호통권65호
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• pp.403-412
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• 2003

건축물의 바닥판에 대한 합성슬래브 시스템의 사용이 점차 확대되어 오피스 빌딩을 중심으로 널리 사용되고 있다. 최근에는 주상복합형 및 주거용 건물에 대한 확대 적용을 휘해 하부면이 평탄한 플랫 데크플레이트의 필요성이 대두됨에 따라 플랫 데크플레이트가 개발되고 있다. 또한 합성슬래브시스템의 바닥판 상부에 와이어메쉬 대신 일체형으로 생산되는 익스팬디드 메탈을 적용할 경우, 원가 절감, 공기 단축 효과도 기대할 수 있을 것이다. 본 연구에서는 익스팬디드 메탈을 와이어메쉬의 대체재로 사용하여 이를 하부면이 평탄한 플랫 데크플레이트와 결합시킨 신형식의 합성블래브시스템을 제안하였다. 총 12개의 시험체에 대한 실험을 통해 그 구조성능을 평가하고자 하였다. 실험 결과는 시험체의 최대내력과 파괴거동 등을 중심으로 요약하여 나타냈다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1606-1611
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• 2005

The goal of this paper is to develop a self localization of mobile robot using UHF RFID landmark. We present landmark, a location sensing archetype system that uses UHF Radio Frequency Identification (UHF RFID) technology for locating objects inside buildings. The major advantage of landmark is that it improves the overall accuracy of locating objects by utilizing the concept of reference tags. Based on experimental analysis, we demonstrate that passive UHF RFID is a viable and cost-effective candidate for indoor location sensing. We conduct a series of experiments to evaluate performance of the positioning of the landmark System. In the standard setup, we place RF Reader which has two antennas and 25 tags in our lab. This research uses the assumption-based coordinates (ABC) algorithm[3] for determining the localization of robot. Also, we show how Radio Frequency Identification (UHF RFID) can be used in robot-assisted indoor navigation for the visually impaired. The experiments illustrate that passive UHF RFID tags can act as reliable landmark that trigger local navigation behaviors to achieve global navigation objectives.