• The Journal of Asian Finance, Economics and Business
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• 제6권3호
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• pp.27-40
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• 2019

The study examines the effects of growth opportunities, debt maturity and liquidity risk on leverage, making use of a large panel of Chinese listed firms. Research on capital structure has broadened its scope from a single capital structure decision (the debt/equity choice) to various attributes of the debt in firms' capital structure. We use the system Generalized Method of Moments estimator to control for unobserved heterogeneity and the potential endogeneity of regressors. We find a negative relationship between growth opportunities and leverage. Further, we find that while the proportion of short-term debt attenuates the negative effect of growth opportunities on leverage, it negatively affects leverage as predicted by the liquidity risk hypothesis. When we distinguish between state owned firms and private controlled firms, we find evidence that these effects are only relevant to private controlled firms. However, our analysis indicates that the economic implication of liquidity risk effect is much lower for Chinese firms than that observed in the literature for US firms. Our study suggests that these differences can be explained by differences in the institutional environment in which firms operate. This finding related to Diamond's (1991) liquidity risk hypothesis extends our understanding of the relationship between liquidity risk and the debt maturity choice.

• 한국산업정보학회논문지
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• 제10권4호
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• pp.110-119
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• 2005

본 논문은 공급사슬구조를 크게 공급네트워크(supply network), 전환네트워크(conversion network), 그리고 유통네트워크(distribution network)라는 세 유형의 구조로 구분하였으며 각 공급사슬구조별 경영성과에 어떠한 영향을 미치는가에 대하여 국내 103개 상장기업을 대상으로 실증분석을 하였다. 또한 경영성과에 대하여서는 균형성과표(Balanced Scorecard; BSC) 모형을 이용하였다. 연구결과, 학습 및 성장성과, 고객성과, 재무성과의 경우 공급사슬구조에 따른 경영성과간 차이가 있음이 검증되었으나, 내부프로세스성과의 경우 경영성과간 차이가 통계적으로 유의하지 않았다. 또한, Scheff의 다중비교 결과에 따라 유통네트워크 중심기업의 경우 다른 공급사슬구조보다 상대적으로 경영성과가 높은 것으로 나타났다.

• 한국멀티미디어학회논문지
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• 제4권2호
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• pp.145-160
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• 2001

통신 및 컴퓨터의 보급 발전을 통해 공개 네트워크 상에서 그룹에 기반한 통신 응용 서비스의 요구가 증가하고 있다. 이러한 필요성에 따라 멀티캐스트 기반 구조에 대한 연구가 활발히 진행되고 있다. 하지만 멀티캐스트 구조에 대한 안전성과 효율성 및 확장성 부분에 대한 해결책은 아직 미비한 상태이다. 본 연구에서는 기존의 대표적인 멀티캐스트 키 관리 구조를 고찰함과 동시에 안전성과 효율성 및 확장성을 분식한다. 이에 기초해 확장성을 제공하는 안전하고 효율적인 멀티캐스트 키 관리 구조를 제안하고, 기존 방식과 통신 및 계산량 부분에 비교 분석을 통해 그 효율성을 확인한다.

• 지능정보연구
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• 제5권1호
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• pp.13-34
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• 1999

Building a knowledge base effectively has been an important research area in the expert systems field. A variety of approaches have been studied including rules, semantic networks, and frames to represent the knowledge base for expert systems. As the size and complexity of the knowledge base get larger and more complicated, the integration of knowledge based with database technology cecomes more important to process the large amount of data. However, relational database management systems show many limitations in handing the complicated human knowledge due to its simple two dimensional table structure. In this paper, we propose Object-Oriented Knowledge Store (OOKS), a knowledge base model on the basis of a frame sturcture using an object-oriented database. In the proposed model, managing rules for inferencing and facts about objects in one uniform structure, knowledge and data can be tightly coupled and the performance of reasoning can be improved. For building a knowledge base, a knowledge script file representing rules and facts is used and the script file is transferred into a frame structure in database systems. Specifically, designing a frame structure in the database model as it is, it can facilitate management and utilization of knowledge in expert systems. To test the appropriateness of the proposed knowledge base model, a prototype system has been developed using a commercial ODBMS called ObjectStore and C++ programming language.

• 전기학회논문지
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• 제62권9호
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• pp.1199-1208
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• 2013

In recent years, the development of application programs for distribution system analysis and control has been essential part for distribution management system (DMS). In this paper, we propose the common database for application programs of distribution management system. The proposed database model has several characteristics as followings. First, the proposed database model is designed for the common use of almost the whole distribution application software. The static equipment model and dynamic type tables are mixed and the parallel table structure is applied. Second, the linked list structure of database are used for the fast processing of applications. The database model includes the hierarchy and non-hierarchy distribution system structure. Third, the reduction method of distribution database is applied. For this, we present the network reduction rules. The basic concept of reduction rules are the electrical unification of successive line section which has not lateral branches and the removal of simple lateral branches which has no devices and other laterals. Proposed database model is tested for the Jeju system of Korea Electric Power Corporation (KEPCO). Through the test, we verified that the proposed database structure can be effectively used to accomplish the distribution system operation.

• 한국측량학회지
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• 제15권1호
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• pp.91-96
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• 1997

구조물의 안전성확보가 이루어지기 위해서는 구조물의 계획·시공으로부터 관리에 이르기까지 각종 측정이 먼저 실행되어야 하며, 이를 통해 당초설계의 타당성을 검증하고 데이터를 축적함으로서 오랜 시간이 경과함에 따른 이상현상이나 붕괴위험에 대해 사전에 예측할 수 있어야 한다. 최근 측량기술의 향상과 개발에 따른 구조물의 유지관리에 대한 자료를 제공하기 위한 방법으로 근거리사진측량방법을 이용, 구조물의 변형측량을 실시하여 기존 구조물 변형량 계측방법의 신뢰성 문제를 해결하고, 구조물 형태변화에 대한 자료를 제시하여 구조물 유지관리에 활용할 수 있도록 하였다.

• 한국측량학회지
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• 제13권2호
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• pp.219-228
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• 1995

1960년대 이후 건설된 발전시설들이 오늘날에 이르러 노후화 되었고, 급속히 늘어나는 전력 소비량을 충당하기 위해 각종 발전시설들이 확충되고 있다. 따라서 이들 시설물에 대한 안전성확보차원의 조치가 이루어져야 한다. 본 연구에서는 전력구조물의 유지관리방안마련에 대한 일환으로 RC시험보를 제작 구성하여 외력작용시 RC시험 보의 변형 상태에 대한 모니터링과 변형량 산출을 위해 근거리사진측량방법에 대한 방법을 모색하였고, 이를 토대로 토류벽공사현장에 대한 변형량산출 및 모니터링을 통한 변형상태 파악 및 지하굴착으로 인한 인접구조물에 미치는 영향을 측정·해석 하므로서 전력구조물에 대한 유지관리에 활용할 수 있는 자료를 제공하였다.

• 대한산업공학회지
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• 제36권3호
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• pp.203-211
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• 2010

This study examines a cointegrated vector autoregressive (VAR) model where parameters are subject to switch across the regimes in the term structure of interest rates. To employ the regime switching framework, the Markov-switching vector error correction model (MS-VECM) is allowed to the regime shifts in the vector of intercept terms, the variance-covariance terms, the error correction terms, and the autoregressive coefficient parts. The corresponding approaches are illustrated using the term structure of interest rates in the US Treasury bonds over the period of 1958 to 2009. Throughout the modeling procedure, we find that the MS-VECM can form a statistically adequate representation of the term structure of interest rate in the US Treasury bonds. Moreover, the regime switching effects are analyzed in connection with the historical government monetary policy and with the recent global financial crisis. Finally, the results from the comparisons both in information criteria and in forecasting exercises with and without the regime switching lead us to conclude that the models in the presence of regime dependence are superior to the linear VECM model.

• 한국수산과학회지
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• 제54권4호
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• pp.445-455
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• 2021

We aimed to study the structure of the zooplankton community in the Southern Sea of the Republic of Korea. Zooplankton samples were collected in February (winter), May (spring), August (summer), and November (autumn) of 2020. The zooplankton collected belonged to a total of 166 taxa and 12 phyla, including some unidentified individuals and those from upper taxa. The number of taxa collected were the highest in winter at 117, and the lowest in May at 93. The dominant taxa were Oikopleura spp. in the winter, Gastropoda larvae in the spring, and Paracalanus parvus s.l. in the summer and autumn. The community structure of the zooplankton was clearly distinguishable between the seasons. The mean density of zooplankton was the highest in autumn and the lowest in summer (576,039 and 313,000 individuals/1,000 m³, respectively). Based on the analysis of relationships between the density of the six major taxa and environmental factors, a significant correlation (P<0.05) between the four taxa and environmental factors was found. Therefore, in order to understand changes in the zooplankton community, quantitative and qualitative investigations of biological factors as well as physical factors should be conducted.

• 한국조경학회지
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• 제30권1호
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• pp.61-74
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• 2002

The purpose of this study is to propose vegetation management devices through analyzing the actual vegetation, flora, plant community structure and soil chemical concentrations in Weolmi urban nature park, Incheon. The actual vegetation of Weolmi Park in various areas is composed of urbanization area(2 types, 25.9%), landscape planting area(4 types, 16.1%), grass and marsh area(5 types, 7.6%) and mountain forest areal(14 types, 50.4%). The flora is composed of 295 taxa with 80 families, 253 species, 35 varieties and 7 formas, and among them there are 16 naturalized plant families, 39 species, 3 varieties. In reflection of size, the number of the species seems high but most of the them are under influence of human disturbance. Nine survey plots of plant community structure are classified into two groups. One is the semi-natural plant community(Prunus sargentii-Acer palmatum, Quercus accutissma-Prunus sargentii, Quercus serrata-Quercus accutissma-Prunus sargentii, Prunus sargentii, and Zelkova serrata-Prunus sargentii) that migrated finn the planting forest to the natural forest and the other is planting forest(Pinus koraienssis-Pinus thunbergii-Abies holophylla-Chamaectparis obtusa, Prunus sargentii, Pinus thunbergii-Alnus firma, Zelkova serrata). The average pH is 4.65 which means the soil acidity is quite high. The concentration of K, Ca, Mg and base saturation is very low. It seems that the environmental pollutants from Incheon Port and industrial plants near by survey site and long-distance transport of air pollutants from China made the soil condition worse. On the basis of the results above, six vegetation management devices are suggested: 1) removing the hazard plants(Pueraia thunbergiana and Humulus japonica), 2) natural landscape management of the middle and long term, 3) increasing species diversity, 4) Robinia pseudoacacia management, 5) keeping the naturalized plants from being distributed any further inside the mountain forest, 6) improving soil acidification.