• Journal of Computing Science and Engineering
• /
• 제6권3호
• /
• pp.179-192
• /
• 2012

This paper presents novel statistical algorithms for protecting the iTrust information retrieval network against malicious attacks. In iTrust, metadata describing documents, and requests containing keywords, are randomly distributed to multiple participating nodes. The nodes that receive the requests try to match the keywords in the requests with the metadata they hold. If a node finds a match, the matching node returns the URL of the associated information to the requesting node. The requesting node then uses the URL to retrieve the information from the source node. The novel detection algorithm determines empirically the probabilities of the specific number of matches based on the number of responses that the requesting node receives. It also calculates the analytical probabilities of the specific numbers of matches. It compares the observed and the analytical probabilities to estimate the proportion of subverted or non-operational nodes in the iTrust network using a window-based method and the chi-squared statistic. If the detection algorithm determines that some of the nodes in the iTrust network are subverted or non-operational, then the novel defensive adaptation algorithm increases the number of nodes to which the requests are distributed to maintain the same probability of a match when some of the nodes are subverted or non-operational as compared to when all of the nodes are operational. Experimental results substantiate the effectiveness of the detection and defensive adaptation algorithms for protecting the iTrust information retrieval network against malicious attacks.

• 가정과삶의질연구
• /
• 제29권2호
• /
• pp.51-62
• /
• 2011

Financial consumers can invest their financial assets directly or indirectly. This investment type have effect on their financial well-being and may be influenced by their financial characteristics and investment attitude. The purposes of the study were to classify the consumers by direct and indirect investment behavior of their financial assets and to investigate their socio-economic characteristics and investment attitudes to give implications for financial counseling and education. The data came from the 2009 Fund Investors Survey which was conducted by Korea Investors Protection Foundation. Total 2,530 consumers were analyzed using frequency, CROSSTAB, ANOVA and Duncan's multiple range test. In general, consumer tended to be rational in choosing the investment type. Noninvestors consisted of 38.5% of the sample. The economic level was the lowest for the noninvestors. The consumers who invest both indirectly and directly consisted of 21.0% and their economic level was the highest. Their investment tendency was between direct and indirect investors'. The proportion of direct investors ws 12.1% and that of indirect investors was 28.4%. Although the economic levels of indirect investors and direct investors were not statistically different, there were differences in their demographics and investment attitudes. The proportions of those aged 30-39, female and nonmarried were greater for indirect investors. They had the tendency to invest safely and diversely for a long term with reserve money. On the other hand, direct investors tended to be male, married and aged 40-49. They tended to invest intensively for a shorter term and seek returns even with borrowing money.

• 한국콘텐츠학회논문지
• /
• 제13권11호
• /
• pp.176-186
• /
• 2013

본 연구는 최근 빈번하게 진행되고 있는 국내 의료서비스기관들의 대형화 및 집단화 움직임에 대하여 동 산업이 규모 또는 범위의 경제(Economies of Scale and Scope)를 실현할 수 있는지를 전위로그비용함수 추정을 통하여 분석하였다. 추정결과 계수에 따라 다소 차이는 있지만 여타 서비스의 생산수준의 변화에 의해 영향을 받는 특정 서비스 생산의 한계비용을 나타내는 계수들 모두 통계적으로 유의함을 보였다. 추정된 단일생산물 규모의 경제(Single-Product Scale Economy: SSE)계수들 뿐만 아니라 전반적인 약 규모의 경제(Ray Scale Economies: RSE)값 모두 1보다 작은 수치를 나타남으로서 한국 의료서비스기관들의 서비스생산에 규모 경제가 존재함을 보여주었다. 범위의 경제 존재여부의 분석을 위한 상호 서비스생산에 있어서 비용의 상보성 추정에서도 모두 90% 이상의 통계적 유의수준을 보였다. 특히 외래환자와 입원환자 진료서비스 간, 입원환자 진료서비스와 제 증명서발급 및 기타 서비스 활동 간에 있어서는 범위의 경제뿐만 아니라 비용의 상보성이 존재함을 보여주었다.

• 한국산림과학회지
• /
• 제96권3호
• /
• pp.251-258
• /
• 2007

항공 Lidar 기술을 이용한 산림조사 기법은 현지조사 및 항공사진을 이용한 기존 조사방법의 한계를 극복할 수 있는 대안으로 떠오르고 있다. 본 연구에서는 국내 산림지형의 특성을 고려하여 개체목 인식 및 수고(樹高)추출을 위한 항공 Lidar자료의 기본적인 처리기법을 제시하고자 한다. 경기도 유명산 조림지를 대상으로 촬영된 항공 Lidar 원시자료로부터 비지면점을 제거하는 기법을 적용하여 순수 지표면을 표현하는 수치표고모형자료(DEM)를 생성하였다. 이렇게 제작된 DEM자료를 기반으로 비지면점에 해당하는 신호값들을 추출한 후 수관고모형(CHM)자료를 생성하였다. CHM자료에 개체목의 수고를 추출하는 필터링 기법을 개발하였다. 연구 지역의 낙엽송 및 잣나무 표본임분을 대상으로 항공사진 및 현지 측정된 자료와 비교한 결과, 개체목의 본수는 90% 이상의 정확도로 추출되었으며, 수고는 평균 1.1m 낮게 추정되었다.

• 산업경영시스템학회지
• /
• 제43권3호
• /
• pp.53-60
• /
• 2020

Evaluating the operational efficiency of electric vehicle charging stations (EVCSs) is important to understand charging network evolution and the charging behavior of electric vehicle users. However, aggregation of efficiency performance metrics poses a significant challenge to practitioners and researchers. In general, the operational efficiency of EVCSs can be measured as a complicated function of various factors with multiple criteria. Such a complex aspect of managing EVCSs becomes one of the challenging issues to measure their operational efficiency. Considering the difficulty in the efficiency measurement, this paper suggests a way to measure the operational efficiency of EVCSs based on data envelopment analysis (DEA). The DEA model is formulated as constant returns of output-oriented model with five types of inputs, four of them are the numbers of floating population and nearby charging stations, distance of nearby charging stations and traffic volume as desirable inputs and the other is the traffic speed in congestion as undesirable one. Meanwhile, the output is given by the charging frequency of EVCSs in a day. Using real-world data obtained from reliable sources, we suggest operational efficiencies of EVCSs in Seoul and discuss implications on the development of electric vehicle charging network. The result of efficiency measurement shows that most of EVCSs in Seoul are inefficient, while some districts (Nowon-gu, Dongdaemun-gu, Dongjak-gu, Songpa-gu, Guro-gu) have relatively more efficient EVCSs than the others.

• 통상정보연구
• /
• 제14권4호
• /
• pp.545-562
• /
• 2012

전자무역 해외시장조사, 계약, 신용조사, 거래알선, 결제, 보험, 운송 등 무역거래 전반의 프로세스를 통합하여 구매효율성을 높이고, 시간단축 등을 통해 전자무역 업무의 효율성 및 생산성을 높일 수 있는 장점을 가지고 있다. 본 연구는 전자무역업무의 몰입 요인인 무역업체 종업원이 해외시장조사업무의 몰입, 상역업무의 몰입, e-LC업무의 몰임, 통관업무의 몰입, e-B/L 및 Logistics업무의 몰입, 결제 및 e-Nego업무의 몰입 등을 개발하여, 전자무역업무의 성과에 미치는 영향을 분석하고 있다. 분석결과, "해외시장 조사업무의 몰입", "e-LC업무의 몰입", "통관업무의 몰입"과 "e-B/L 및 Logistic 업무의 몰입" 그리고 "결제 및 e-Nego업무의 몰입"의 요인들은 전자무역 성과에 유의한 영향을 미치고 있다. 반면 "상역업무의 몰입"은 전자무역 성과에 유의한 영향을 미치고 있지 않다는 분석 결과가 나왔다. 본 연구에서 나타난 바와 같이 전자무역은 무역업체에게 유효한 효과가 있기 때문에 글로벌 전자무역과 시스템 개발에 노력해야 하며, 각 관련부처간의 시스템 연계의 통일화를 기해야 할 것이다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 B
• /
• pp.1243-1247
• /
• 1996

In this paper, a small PLC system is designed and developed for the distributed building control and fire control system. It uses 8031, a 8-bit micro controller from Intel Inc. The size of the PLC is $7cm{\times}8cm$ and the PLC can accept 4 sensor inputs and drive 4 relay outputs, which operates at 24V. Multiple access of PLC by one host computer is implemented by assigning a unique 10 to each PLC, which ranges from 0 to 126. The operation starts by sending a command packet from host computer to a PLC and the PLC of the same 10 fetches the command packet by comparing the first byte of the command packet with its own 10. The PLC is programmed to perform a various functions and the function is selected by the content of the command byte, which is the second byte of the command packet. The third byte, which is the last byte, is a checksum byte. The checksum byte is the sum of the first byte and the second byte and is used to detect the communication error. Depending on the content of the command byte, PLC performs the desired function and returns the response packet back to the host computer. The response packet is also a three-byte packet, 10 byte, response byte and checksum byte. For the independent operation of PLC without being controlled by the host computer, variable length RULE data packet is sent to PLC. In case the communication line is broken, the PLC perform the independent operation by referencing the RULE data. The applicable areas are; building automation system, distributed factory automation, measurement of temperature of toxic or dangerous area.

• 대한원격탐사학회지
• /
• 제25권6호
• /
• pp.547-557
• /
• 2009

LIDAR (LIght Detection And Ranging) is an active remote sensing technology which provides 3D coordinates of the Earth's surface by performing range measurements from the sensor. Early small footprint LIDAR systems recorded multiple discrete returns from the back-scattered energy. Recent advances in LIDAR hardware now make it possible to record full digital waveforms of the returned energy. LIDAR waveform decomposition involves separating the return waveform into a mixture of components which are then used to characterize the original data. The most common statistical mixture model used for this process is the Gaussian mixture. Waveform decomposition plays an important role in LIDAR waveform processing, since the resulting components are expected to represent reflection surfaces within waveform footprints. Hence the decomposition results ultimately affect the interpretation of LIDAR waveform data. Computational requirements in the waveform decomposition process result from two factors; (1) estimation of the number of components in a mixture and the resulting parameter estimates, which are inter-related and cannot be solved separately, and (2) parameter optimization does not have a closed form solution, and thus needs to be solved iteratively. The current state-of-the-art airborne LIDAR system acquires more than 50,000 waveforms per second, so decomposing the enormous number of waveforms is challenging using traditional single processor architecture. To tackle this issue, four parallel LIDAR waveform decomposition algorithms with different work load balancing schemes - (1) no weighting, (2) a decomposition results-based linear weighting, (3) a decomposition results-based squared weighting, and (4) a decomposition time-based linear weighting - were developed and tested with varying number of processors (8-256). The results were compared in terms of efficiency. Overall, the decomposition time-based linear weighting work load balancing approach yielded the best performance among four approaches.

• 국제지역연구
• /
• 제13권3호
• /
• pp.29-49
• /
• 2009

본 연구의 목적으로는 정보투명성, 간사은행의 국적여부, 신용등급 등이 약정수수료와 어떤 연관성이 있는가를 일본에서 발생한 331개의 신디케이트론 샘플을 이용하여 분석하였다. 신디케이트론이란 다수의 은행이 차관단을 형성하여 공통의 조건으로 일정금액을 차입자에게 공동융자하는 것을 말하며, 일본신디케이트론 시장은 2008년 기준 $2830억 으로 전년대비 36%의 성장률을 보여주고 있다. 본 연구의 주요 결과로 첫째, 일본 차입자에 대한 정보투명도가 떨어질수록 은행은 높은 약정수수료를 부과하였다. 둘째, 차관단에서의 주간사은행이 일본은행일 경우 보다 높은 약정수수료를 요구함을 알 수 있었다. 셋째, 일본 차입자의 신용등급이 낮을수록 차입자의 부채비용은 증가하고 있다. 마지막으로 은행들은 스프레드뿐만 아니라 비이자수익인 약정수수료를 통해서도 수익률을 증대시킴을 알 수 있다. 약정수수료에 가장 연관성이 높은 스프레드를 통제변수로 사용하여 위의 결과들을 도출하였으며 일본기업을 이용한 실증연구를 하였다는 점에서 본 연구의 의의가 있다고 할 수 있다.

• Journal of Korea Trade
• /
• 제24권6호
• /
• pp.1-18
• /
• 2020

Purpose - This study investigates whether a listing effect exists in cross-border M&As and whether the effect can be attributed to the uncertainty of the GDP growth rate in the target firm's home country. We apply a joint variable analysis using M&A announcement data from the Korea Exchange (KRX), Shanghai Stock Exchange (SSE), and the Taiwan Stock Exchange (TWSE) from 2004 to 2013. We also conduct an event study using the measure of the uncertainty of the GDP growth rate (based on IMF statistics) in 55 target countries. Design/methodology - We measure the abnormal return (AR) using the market-adjusted model. We test the significance of the AR and the cumulative abnormal return (CAR) using a one-sample t-test. We examine the characteristics of the CARs depending on whether the target company is listed by applying a difference analysis using CAR as a test variable. In addition, we set CAR (-5, +5) as a dependent variable to identify the cause of the listing effect, and test both the financial characteristic variables of the acquirer and the collective characteristic variables of the merger as independent variables in the multiple regression analysis. Findings - First, we find the listing effect of cross-border M&As in the KRX, SSE, and TWSE, which represent the capital markets in Korea, China, and Taiwan, respectively. This listing effect persists during the global financial crisis and has a negative effect on the wealth of acquiring shareholders, especially when the target countries are emerging markets. Second, greater uncertainty regarding the target countries' economic growth in cross-border M&As has a negative effect on the wealth of acquiring firms' shareholders. Third, our empirical analysis demonstrates that the listing effect is attributable to the fact that firms listed in a target country with greater uncertainty of economic growth are more directly and greatly exposed to uncertain capital markets through stock markets, than are unlisted firms. Originality/value - This study is significant in that it presents a new strategic perspective in the study of cross-border M&As by demonstrating empirically that the listing effect is attributable to the uncertainty regarding the economic development of the target firms' home countries.