• Journal of the KSME
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• v.31 no.7
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• pp.626-635
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• 1991

직접구동 로봇의 특성과 문제점에 대하여 기술하고 기계설계와 제어방식에 의한 대책 및 개선 방향을 해설하였다. 직접구동 로봇은 고속, 고정밀도, 토크제어의 가능 등 여러 가지 좋은 잠재 력을 가지고 있는 반면 자체 중량에 비하여 가반중량이 작고 관절 간의 간섭 및 비선형력이 크며 부하감도가 높은 등의 문제점이 있음을 나타내고 모터의 배치나 기구의 변환에 의해 이와 같은 문제점을 어느 정도 개선할 수 있음을 보였다. 또한 비간섭 . 자세독립제어, 토크피드백 제어에 의하여 직접구동의 장점을 충분히 활용하기 위해서는 아직도 해결하여야 할 문제가 많다. 그 중에 무엇보다도 중요한 것은 소형 경량이면서 높은 토크를 발생시킬 수 있는 모터의 개발이다. 최근 초음파 모터의 연구개발이 활발한데 이를 이용한 직접구동 모터의 개발이 기대된다.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03a
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• pp.227-247
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• 2004

직접기초(Shallow Foundation)란 상부구조로부터의 하중을 직접 지반에 전달시키는 형식의 기초로써 기초의 최소폭(B)과 근입깊이(D$_{f}$ )와의 비가 대체로 1.0이하인 경우나(Terzaghi, 1943), D$_{f}$ /D$\leq$1-4인 경우에도 직접기초라 정의되었다(Das, 1984). 현재, 깊은 기초보다 이용이 적지만 허용지지력과 허용침하량이 확보되는 지반이라면 깊은기초보다 훨씬 경제적인 설계를 할 수 있는 것이 직접기초이다. 이러한 직접기초의 지지력에 관한 이론적인 기본 개념은 Terzaghi(1943)에 의하여 처음 정립되었고, 그 이후 Meyerhof(1951, 1963), Hansen(1970), Vesic(1973, 1975), Chen(1975) 등에 의하여 각기 다른 지지력 산정식이 제안되었다.(중략)

• Journal of the Korean Geographical Society
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• v.28 no.4
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• pp.379-391
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• 1993

Present-day world economy is characterized by : technology nationalism, economic regionalism, market protectionism, multinational corporations, efc. All nations are striving for intensifying national economic rivalry and seeking after their own interests above everything else. Many regions of the world are also forming trading blocs, which could negatively affect nonmember states. The ultimate way to meet these difficulties is to establish production facilities in the countries imposing trade regulations. However, as the existing models of direct forrign investment (DFI) do not account for the particular nature of Korean firm's DFI activities, a new point of departure is imperative. It is because of this that Korean firms have only limited firm-specific advantages, the basic precondition of extant DFI theories, compared with their developed counterparts.

• Journal of the Korean Geotechnical Society
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• v.31 no.3
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• pp.51-62
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• 2015

Shear behavior obtained by direct shear tests is dependent on shear box and boundary condition. The objective of this study is to analyze problems of conventional direct shear test (type-A) and provide the reliable results by developing type-C direct shear apparatus. Experimental tests are carried out for Ulleung sand by using type-A and -C direct shear devices. The soil specimens, which are prepared at the relative density of 60%, and are applied to vertical confining stresses of 50, 100, 200, 300, and 400 kPa, are sheared at a constant shear strain rate of 0.5 mm/min. By comparing the results obtained by type-A and -C direct shear apparatus under constant normal load (CNL) condition, the performance of new one is verified. In addition, two constrained conditions including constant normal load (CNL) and constant pressure (CP) are applied to type-C one. Experimental results show that type-A direct shear apparatus has some problems such as rotating of loading plate and upper shear box, and the frictional forces between soil and inner wall of upper shear box. Thus, the shear strengths obtained by type-A device are overestimated or underestimated depending on shear box and boundary condition. On the other hand, type-C device produces clear and consistent test results regardless of constrained conditions. This study represents that type-C direct shear apparatus not only can solve the problems of type-A direct shear apparatus but provide the reliable results.

• Management & Information Systems Review
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• v.36 no.3
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• pp.113-130
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• 2017

This study examines the effect of direct investment in Asia on firm value for nonfinancial firms listed on KRX between 2006 and 2015. We also explore whether the mediating effects of cashholdings the relationship between direct investment in Asian markets and corporate value. Recently, companies are increasing their cash holdings for risk management. Cashholdings are causing agent problems, which has a negative impact on corporate value. In this case, when the company conducts active investment activities such as foreign direct investment, it is possible to supply the appropriate funds in a timely manner, thereby cashholdings increase the possibility of success of foreign direct investment and alleviate the agent problem of cash holdings. For the analysis, the number of directly invested firms in Korean listed firms is used as the explanatory variables for the Chinese and Vietnamese markets where foreign direct investment is the most active, and cash holding is set as the moderating variable. As a result, direct investment in China and Vietnam showed a positive (+) relationship with firm value, and cashholdings have a positive the relationship between foreign direct investment and firma value. The implications of this paper are as follows. First, it is suggested that the direct value of direct investment can be enhanced the relationship between direct investment and firm value in Asia. In addition, it can be suggested that cash holdings play a role of effective investment supply in firms that implement foreign direct investment, positively affecting corporate value.

• Journal of Energy Engineering
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• v.11 no.4
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• pp.342-349
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• 2002

This paper presents the determination of incentive level of Direct Load Control (DLC) program based on California Test. In the most of the Demand-Side Management (DSM) program, the variables art given by constant value during the DSM program's life time. But, in the case of DLC, variables are depen-dent on the executing number and time of the DLC per year. Therefore, we formulate a newly designed Cal-ifornia Test technique to overcome these problems and to apply effectively to the determination of incentive level of the DLC program. We perform case studies for various scenarios using a proposed formulation and review incentive level of the current DLC program. And we propose a plan to activate the DLC program in the competitive electricity market.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1257-1259
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• 2000

직접토크제어(DTC)가 빠른 포크 응답을 가지고있다는 것은 널리 알려진 사실이다. 이것은 기존의 벡터 제어와는 달리 공간 전압벡터에 의해 직접적으로 토크와 자속이 제어되기 때문이다. 이로 인해 직접토크제어 기법은 그것이 도입되어진 1980년대 중반 이래로 노크의 빠른 응답을 필요로 하는 분야에 점차적으로 적용되어져 왔다. 하지만 이런 장점에도 불구하고 직접토크제어는 히스테리시스 밴드, 속도 그리고 전동기 파라메타의 변화에 따른 스위칭 주파수의 변화와 토크 리플의 증가, 좋은 성능을 위한 높은 제어 주기 등의 몇 가지 단점을 가지고 있었다. 그래서 DTC의 단점들을 해결하기 위해 여러 연구들이 이루어져 왔다. 본 논문에서는 이들 단점들 중 하나인 토크리플을 개선하려한다. 다른 논문들에서도 일정 주파수를 가지는 여러 제어 기법을 사용하여 직접토크제어의 단점을 해결하려 했지만 너무 복잡하고 큰 성능을 나타내지 못했으며 몇몇 논문들은 오히려 직접토크제어의 장점인 빠른 응답성을 잃는 결과도 가져왔다. 그래서 본 논문은 간단한 개념을 가지고 토크리플을 줄이며 일정 스위칭 주파수를 가지므로 DSP를 사용하여 제어하기 용이한 직접토크제어기법을 제안하려 한다.

• Journal of the Korea Society for Simulation
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• v.21 no.1
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• pp.19-26
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• 2012

In this paper, we study the relationship between FDI(Foreign Direct Investment) and economic growth in Kazakhstan. For this research, we, first, investigate the factors that affect FDI infow to Kazakhstan since its independence and determine the degree of their influence. Second, we study the impact of FDI per capita on GDP per capita. To achieve these goals, an empirical study is conducted with 18 years data from 1992 to 2009 from World Bank Database. Data are analyzed using multiple linear regression, time series analysis and Granger causality test. The results show that the determinant of FDI is GDP and economic freedom index in Kazakhstan. Economic growth is affected by FDI, too. Specially, FDI is positively related to GDP and economic freedom index. FDI per capita's impact on GDP per capita is 30.4 dollars increase in GDP per capita by one dollar increase in FDI per capital inflow. The results provides useful information for policy makers to improve obtaining large amount of investments and facilitate economic growth.

• The Journal of Bigdata
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• v.5 no.1
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• pp.41-54
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• 2020

With the recent expansion of Internet channels and the development of financial technology and information and communication technology, direct overseas purchases have expanded. Although direct overseas purchases dominate consumers in terms of price and scarcity by providing relatively low-priced products and products that are difficult to obtain in Korea, there is a higher chance of consumer dissatisfaction in terms of delivery, product, A/S and refund than domestic purchases. Therefore, this study analyzed consumer dissatisfaction caused by active overseas direct purchase and studied ways to improve problems with overseas direct purchase. As a research method, Several statistical data were collected from the Korea Consumer Agency(KCA), the Korea Customs Service(KCS) and the Korea International Trade Association(KITA) and analyzed using the Exploratory Data Analysis Technique (EDA). The analysis confirmed that consumers were not well aware of information about direct overseas purchases and that the type or degree of consumer complaints varied depending on the type of purchase. Therefore, this study suggests a direction for the revitalization of overseas direct purchases by using EDA to identify the overall status of overseas direct purchases and consumer dissatisfaction and to improve them.

• International Area Studies Review
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• v.15 no.3
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• pp.429-449
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• 2011

This study investigated the determinants of the foreign direct investment (FDI) by the Korean firms. We focused on types of FDI such as market-seeking, efficiency-seeking, strategic asset-seeking, resource seeking investment and institutional distance including economic distance, political distance and cultural distance which were affecting Korean FDI decision. We tested our hypotheses using Korean FDI data collected between 1980 and 2010. The result showed that Korean FDI to be associated with market-seeking, efficiency-seeking, strategic asset-seeking investment, and institutional distance such as economic distance. We also examined Korean FDI before and after IMF, and the results indicated that before IMF, Korean FDI was associated with market-seeking and strategic asset-seeking investment. However, after IMF, Korean FDI was associated with market-seeking, efficiency-seeking, strategic asset-seeking investment, and institutional distance such as economic distance.