• Information Systems Review
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• v.8 no.1
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• pp.125-139
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• 2006

Recently, as mobile internet users grow rapidly, mobile internet companies are experiencing a fierce competition to capture new customers. Under this business environment, they try to identify factors that make people use mobile internet in order to satisfy customers by providing better and diversified services. There has been enormous effort to analyze customers' behavior in choose and use mobile internet services. However, there is no one best methodology to identify factors to attract customers yet. Thus, the study applied the flow construct proposed by Csikszentmihalyi(1977) and expanded by Hoffman and Novak(1996) to identify environmental factors of internet which has impact on users' mobile internet usage. To implement the study, the following activities have been done: literature reviews on service acceptance model and flow structure, questionnaire survey, suggestion of the flow model on mobile internet, and hypothesis test. For the study, 242 out of 307 samples collected were statistically analyzed using SPSS 10.0, AMOS 4.0 statistics package. The findings of this study are as follows: First, mobile internet environment factors influencing on challenge of flow antecedent were media characteristics(use of convenience, transmission quality), contents characteristics(uniqueness, timeliness, simplicity). Second, mobile internet environment factors influencing on skill of flow antecedent were contents(uniqueness, timeliness, simplicity), charge(definiteness and diversity of charge), usage(security, instant connectivity). Third, challenge of flow antecedent had a significant effect on flow of mobile internet usage. But it was not statistically significant that skill has an influence on flow. This study discovered the relationship between mobile internet environment factors(media characteristics, contents characteristics, charge characteristics, usage characteristics) and flow experience of mobile internet users which would be a valuable insight for marketing strategies. Results shows that challenge of flow antecedent have a significant impact on flow experience in mobile internet environment. Additional, media characteristics, contents characteristics of mobile internet environment factors is positively correlated with challenge of flow antecedent. In other words, mobile internet companies should provide customers with diverse service and take a challenging attitude to get customers show aggressive attitude in mobile internet usage.

• Journal of Korean Society of Transportation
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• v.27 no.3
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• pp.119-130
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• 2009

The aim of this study is to analyze the effects of DVR(Driving Video Recorder) operation on decreasing the number of traffic accidents, the cost of traffic accident claim, and the behavioral change in drivers' driving. The data for this research are obtained from taxi drivers in Busan. For this, Structural Equation Model and two-way ANOVA are employed for empirical analysis. Overall results of this study show that the number of traffic accidents of 4 taxi corporations in Busan has decreased by average 32.7 percent after using DVRs. In addition, as to the cost of taxi accident claims, it is expected that the DVR operation has a considerable effect on economic benefits of taxi corporations. Moreover, this study could make clear the difference in behaviors between DVR users and non-users, and discriminate the positive and negative impacts of the DVR operation on the drivers' driving behavior. The study quantitatively examined the indirect impact of 'attitude', 'subject norm' and 'behavioral control' factors on planned 'behavior', and the direct impact of 'behavioral control' factor on the planned 'behavior'. This study suggests that they should add the video recoding function of DVRs when operation recorder(blackbox for the car) is obligatorily set up on cars for business by traffic security law.

• Journal of Korea Water Resources Association
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• v.41 no.1
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• pp.1-15
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• 2008

The purpose of this study is to propose a procedure that will be able to find the most efficient sets of weight coefficients for the Geum-River basin in Korea. The result obtained from multi-objective optimization model is inherently sensitive to the weight coefficient on each objective. In multi-objective reservoir operation problems, the coefficient setting may be more complicated because of the natural variation of inflow. Therefore, for multi-objective reservoir operation problems, it may be important for modelers to provide reservoir operators with appropriate sets of weight coefficients considering the inflow variation. This study presents a procedure to find an appropriate set of weight coefficients under the situation that has inflow variation. The proposed procedure uses GA-CoMOM to provide a set of weight coefficient sets. A DEA-window analysis and a cross efficiency analysis are then performed in order to evaluate and rank the sets of weight coefficients for various inflow scenarios. This proposed procedure might be able to find the most efficient sets of weight coefficients for the Geum-River basin in Korea.

• Journal of Korea Water Resources Association
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• v.45 no.8
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• pp.839-851
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• 2012

When we evaluate the water supply capacity of a river basin, it is a common practice to gradually increase the water demand and check if the water demands are met. This practice is not only used in the simulation approach, but also in the optimization approach. However, this trial and error approach is a tedious task. Hence, we propose a two-phase method. In the first phase, by assuming that the decision maker has complete information on inflow data, we use a goal programming model that can generate the maximum water supply capacity at one time. In the second phase, we simulate the real-time operation for the critical period by utilizing the water supply capacity given by the goal programming model under the condition that there is no foresight of inflow. We applied the two-phase method to the Geum-River basin, where multi-purpose weirs were newly constructed. By comparing the results of the goal programming model with those of the real-time simulation model we could comprehend and estimate the effect of perfect inflow data on the water supply capacity.

• Journal of Navigation and Port Research
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• v.29 no.3 s.99
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• pp.203-213
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• 2005

The International Maritime Organization(IMO) which is responsible for measures to improve the safety and security of international shipping and to prevent marine pollution from ships is a specialized agency of the United Nations. It is involved in legal matters, including liability and compensation issues and the facilitation of international maritime traffic as well. But the ROK has not been actively coping with the environment of the shipping industry because of the absence of the organization or researching bodies that specialized in the field related to IMO. Therefore this paper investigates the maritime administration system of the major countries such as the USA, japan and the UK. And particularly by conducting IMO research and responding system, this study gathers relevant materials from those countries for the comparison and analysis with the purpose of providing the ROK with the assistance in forming the responding measures in the shipping and shipbuilding industries.

• Journal of Internet Computing and Services
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• v.6 no.3
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• pp.17-30
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• 2005

A PAK(Password-Authenticated Key Exchange) protocol is used as a protocol to provide both the mutual authentication and allow the communication entities to share the session key for the subsequent secure communication, using the human-memorable portable short-length password, In this paper, we propose distributed key exchange protocols applicable to a smartcard using the MTI(Matsumoto, Takashima, Imai) key distribution protocol and PAK protocol. If only one server keeps the password verification data which is used for password authentication protocol. then It could easily be compromised by an attacker, called the server-compromised attack, which results in impersonating either a user or a server, Therefore, these password verification data should be distributed among the many server using the secret sharing scheme, The Object of this paper Is to present a password-based key exchange protocol which is to allow user authentication and session key distribution, using the private key in a smartcard and a password typed by a user. Moreover, to avoid the server-compromised attack, we propose the distributee key exchange protocols using the MTI key distribution protocol, And we present the security analysis of the proposed key exchange protocol and compare the proposed protocols with the existing protocols.

• Journal of the Korea Convergence Society
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• v.2 no.4
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• pp.29-37
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• 2011

Dispersed generation (DG) such as wind power (WP) and Photovoltaic systems (PV) that has been promoted at the national level recently is mainly being introduced into distribution systems adjacent to consumers because it is generation on a small scale when compared to current generation. Due to its characteristics, DG can be operated by interconnection with distribution systems to present security of more stable power and efficient use of power facilities and resources. Problems on protection coordination of distribution systems by reverse flow of DG can roughly be divided into three possibilities: excess in rated breaking capacity (12.5KA) of protective devices by a fault in DG current supply, failure to operate protective devices by an apparent effect that can occur by reduction in impedance parallel circuit fault current due to interconnection of DG, and malfunction of protective devices by interconnection transformer connection type. The purpose of this study is to analyze problems in protection coordination that can occur when DG is operated by interconnection with distribution systems by conducting modeling and simulations by using theoretical symmetrical components and MATLAB/SIMULINK to present methods to improve such problems.

• Journal of KIISE:Information Networking
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• v.36 no.1
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• pp.12-23
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• 2009

Sensor networks deployed in battlefields to support military operations or deployed in natural habitats to monitor the rare wildlifes must take account of protection of the location of valuable assets(i.e., soldiers or wildlifes) from an adversary or malicious tracing as well as the security of messages in transit. In this paper we propose a routing protocol GSLP(GPSR-based Source-Location Privacy) that is capable of enhancing the location privacy of an active source node(i.e., message-originating node) in the presence of multiple dormant sources(i.e., nodes lying nearby an asset whose location needs to be secured). Extended is a simple, yet scalable, routing scheme GPSR(greedy perimeter stateless routing) to select randomly a next-hop node with a certain probability for randomizing paths and to perform perimeter routing for detouring dormant sources so that the privacy strength of the active source, defined as safety period, keeps enhanced. The simulation results obtained by increasing the number of dormant sources up to 1.0% of the total number of nodes show that GSLP yields increased and nearly invariant safety periods, while those of PR-SP(Phantom Routing, Single Path), a notable existing protocol for source-location privacy, rapidly drop off as the number of dormant sources increases. It turns out that delivery latencies of GSLP are roughly less than two-fold of the shortest path length between the active source and the destination.

• Strategy21
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• s.39
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• pp.5-46
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• 2016

North Korea's 4th nuclear test on Jan. 6 and following developments once again awakened the world into seriousness of the nuclear matters on the Korean peninsula. On March 2, UNSC adopted Resolution 2270 which is complemented by Seoul government's measures such as withdrawal from the Gaesung Industrial Complex (Feb. 9) and announcement of unilateral sanction (March 8). Seoul government also strongly urged the international community to strangle North Korea's 'financial resources.' The U.S., Japan, China, and other countries have issued unilateral sanctions to complement the UNSC measure. South Korea and the U.S. conducted their annual joint military drill (Resolve-Foal Eagle) in the largest-ever scale. North Korea, however, responded with demonstration of its nuclear capabilities and announcement of de facto 'nuclear-first' politics. North Korea test-fired a variety of delivery vehicles, threatened nuclear strikes against South Korea and the U.S., and declared itself as an 'invincible nuclear power armed with hydrogen bombs' at the 7th Workers 'Party Congress held in May, 2016. Considering the circumstantial evidences, the North's 4th nuclear test may have been a successful boosted fission bomb test. North Korea, and, if allowed to go on with its nuclear programs, will become a nuclear power armed with more than 50 nuclear weapons including hydrogen bombs. The North is already conducting nuclear blackmail strategy towards South Korea, and must be developing 'nuclear use' strategies. Accordingly, the most pressing challenge for the international community is to bring the North to 'real dialogue for denuclearization through powerful and consistent sanctions. Of course, China's cooperation is the key to success. In this situation, South Korea has urgent challenges on diplomacy and security fronts. A diplomatic challenge is how to lead China, which had shown dual attitudes between 'pressure and connivance' towards the North's nuclear matters pursuant to its military relations with the U.S, to participate in the sanctions consistently. A military one is how to offset the 'nuclear shadow effects' engendered by the North's nuclear blackmail and prevent its purposeful and non-purposeful use of nuclear weapons. Though South Korea's Ministry of Defense is currently spending a large portion of defense finance on preemption (kill-chain) and missile defense, they pose 'high cost and low efficiency' problems. For a 'low cost and high efficiency' of deterrence, South Korea needs to switch to a 'retaliation-centered' deterrence strategy. Though South Korea's response to the North's nuclear threat can theoretically be boiled down into dialogue, sanction and deterrence, now is the time to concentrate on strong sanction and determined deterrence since they are an inevitable mandatory course to destroy the North' nuclear-first delusion and bring it to a 'real denuclearization dialogue.'

• The KIPS Transactions:PartB
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• v.9B no.6
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• pp.853-862
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• 2002

Face Detection can be defined as follows : Given a digitalized arbitrary or image sequence, the goal of face detection is to determine whether or not there is any human face in the image, and if present, return its location, direction, size, and so on. This technique is based on many applications such face recognition facial expression, head gesture and so on, and is one of important qualify factors. But face in an given image is considerably difficult because facial expression, pose, facial size, light conditions and so on change the overall appearance of faces, thereby making it difficult to detect them rapidly and exactly. Therefore, this paper proposes fast and exact face detection which overcomes some restrictions by using neural network. The proposed system can be face detection irrelevant to facial expression, background and pose rapidily. For this. face detection is performed by neural network and detection response time is shortened by reducing search region and decreasing calculation time of neural network. Reduced search region is accomplished by using skin color segment and frame difference. And neural network calculation time is decreased by reducing input vector sire of neural network. Principle Component Analysis (PCA) can reduce the dimension of data. Also, pose estimates in extracted facial image and eye region is located. This result enables to us more informations about face. The experiment measured success rate and process time using the Squared Mahalanobis distance. Both of still images and sequence images was experimented and in case of skin color segment, the result shows different success rate whether or not camera setting. Pose estimation experiments was carried out under same conditions and existence or nonexistence glasses shows different result in eye region detection. The experiment results show satisfactory detection rate and process time for real time system.