• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.2
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• pp.79-93
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• 1990

The purpose of this study is to establish better residential environment in APT. complex. In this study, the actual conditions of exterior space, user behavior and degree of satisfaction are investigated and analyzed on the 5 high-rise story APT complex in Taegu city. The results of this study were as follow ; The size and arrangement of organizational elemnnt to exterior space in APT. complex have been regulated by law and regulations as the buildings coverage and floor space index, but housinghold and accessibility to the racility will be simultaneously considered to raise Quality of the residential environoment. The main user behavior to exterior space in APT. complex was practical activity and the user behavior pattern by week and among APT. complex were found similiarly. In the ratio of use to exterior space in APT. Complex, that of high-rise residents were lower than that of lowrise residents. In the degree of satisfaction by property of variables to exterior environment In APT. comples, physical of buildings, social - psychologic, managerial economical, physical property of exterior space were estimated positively, but properly of facility were estimated negatively. The degee of satisfaction to exterior environment in APT. complex was highly Influenced by green space, site size. As a result of ractor analysis, the four factors were drawn out from exterior environment in APT. complex. and the factors that have an effect on the degree of residents' satisfaction by factorscore were found in the order of importance as fallow ; managemental, physical, environmental, organizalional factor. Therefore, devilopment of APT. complex should be considered in a view of environmental psychology according to physical organization for used in the future. It is recommended that this problems should be necessitated to be more deeply studies in the future.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1079-1086
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• 2008

In this paper, we propose a Cyclic-Prefix Code Division Multiple Access system that uses Sequences with Good Autocorrelation property(GAS-CP-CDMA) and analyze the uplink signal-to-noise ratio performance of that system. Phase-shifted sequences are used for differentiating users. The signals of the GAS-CP-CDMA system experience no (or very little) interferences from co-cell signals because of the good autocorrelation property, but user signals of adjacent cells may yield interferences. The frequency reuse factor in the ordinary CDMA system is around 0.6 and the interference from adjacent cells is about 40 percent of the total interference in the conventional CDMA system. Our numerical analysis shows that the frequency reuse factor and user capacity versus signal-to-noise ratio of the GAS-CP-CDMA system are improved comparing to the conventional CDMA system. The uplink user capacity of the proposed system can be increased up to about twice of that of the conventional CDMA system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.4
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• pp.75-90
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• 2004

At Asiacrypt 2003, Shin et al., have proposed a new class for Authenticated Key Establishment (AKE) protocol named Leakage-Resilient AKE ${(LR-AKE)}^{[1]}$. The authenticity of LR-AKE is based on a user's password and his/her stored secrets in both client side and server side. In their LR-AKE protocol, no TRM(Tamper Resistant Modules) is required and leakage of the stored secrets from $.$my side does not reveal my critical information on the password. This property is useful when the following situation is considered :(1) Stored secrets may leak out ;(2) A user communicates with a lot of servers ;(3) A user remembers only one password. The other AKE protocols, such as SSL/TLS and SSH (based or PKI), Password-Authenticated Key Exchange (PAKE) and Threshold-PAKE (T-PAKE), do not satisfy that property under the above-mentioned situation since their stored secrets (or, verification data on password) in either the client or the servers contain enough information to succeed in retrieving the relatively short password with off-line exhaustive search. As of now, the LR-AKE protocol is the currently horn solution. In this paper, we prove its security of the LR-AKE protocol in the standard model. Our security analysis shows that the LR-AKE Protocol is provably secure under the assumptions that DDH (Decisional Diffie-Hellman) problem is hard and MACs are selectively unforgeable against partially chosen message attacks (which is a weaker notion than being existentially unforgeable against chosen message attacks).

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.2
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• pp.127-140
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• 2009

Recently, software piracy is one of the serious crimes for the digital materials. It makes economically devasting to the software industry and the market. In particular, it is a widespread phenomenon among university students in Korea and negative affects in measuring social and cultural level. Many studies have been focused on the users' intention of the software piracy for making anti-piracy policy. The purpose of this study is to investigate the factors affecting university students' software piracy intention. The survey includes responses from 271 university students in a school of business adminstration. The research model was estimated with multiple regression. The analysis showed results that user's characteristics, subjective norms, and perceived software quality were significantly related to intention of software piracy, but security policy was not. Perceived importance of intellectual property has negative impact on user's software piracy intention. Based on the findings, we suggest the implications for developing and implementing appropriate policies for anti-piracy.

• Journal of Communications and Networks
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• v.1 no.3
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• pp.182-188
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• 1999

The optimal joint maximum-likelihood sequence estima-for using an array of antennas is derived for synchronous direct sequence-code division multiple access (DS-CDMA) system. Each user employs a rate 1/n convolutional code for channel coding for the additive white Gaussian noise (AWGN) channel. The array re-ceiver structure is composed of beamformers in the users' direc-tions followed by a bank of matched filters. The decoder is imple-mented using a Viterbi algorithm whose states depend on the num-ber of users and the constraint length of the convolutional code. The asymptotic array multiuser coding gain(AAMCG)is defined to encompass the asymptotic multiuser coding gain and the spatial information on users' locations in the system. We derive the upper and lower bounds of the AAMCG. As an example, the upper and lower bounds of AAMCG are obtained for the two user case where each user employes the maximum free distance convolutional code with rate 1/2. The enar-far resistance property is also investigated considering the number of antenna elements and user separations in the space.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.290-296
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• 2006

In this paper, a generalized blind adaptive algorithm is introduced for multi-user detection of direct sequence code division multiple access (OS-COMA) wireless communication systems. The main property of the proposed algorithm is its ability to resolve the multipath fading channel resulting in inter symbol interference (ISI) as well as multiple access interference (MAI). Other remarkable properties are its low complexity and mitigation to the near-far problem as well as its insensitivity to asynchronous transmission. The proposed system is based on the minimization of the output energy and convergence to the minimum mean square error (MMSE) detector. It is blind in the sense that it needs no knowledge of the other users' signatures, only the intended user signature and timing are required. Furthermore, the convergence of the minimum output energy (MOE) detector to the MMSE detector is analytically proven in case of M-ary PSK. Depicted results show that the performance of the generalized system dominates those previously considered. Further improvements are obtained when multiple input multiple output (MIMO) technique is employed.

• Spatial Information Research
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• v.20 no.4
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• pp.83-92
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• 2012

Location-based services (LBS) are increasingly popular due to the improvement of geo-positioning capabilities and wireless communication technology. However, in order to enjoy LBS services, a user requesting a query must send his/her exact location to the LBS provider. Therefore, it is a key challenge to preserve user's privacy while providing LBS. To solve this problem, the existing method employs a 2PASS cloaking framework that not only hides the actual user location but also reduces bandwidth consumption. However, 2PASS does not fully guarantee the actual user privacy because it does not take the real user distribution into account. Hence, in this paper, we propose a nearest neighbor query processing algorithm that supports K-anonymity property based on the weighted adjacency graph(WAG). Our algorithm not only preserves the location of a user by guaranteeing k-anonymity in a query region, but also improves a bandwidth usage by reducing unnecessary search for a query result. We demonstrate from experimental results that our algorithm outperforms the existing one in terms of query processing time and bandwidth usage.

• Journal of Internet Computing and Services
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• v.12 no.2
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• pp.9-17
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• 2011

This paper proposes an algorithm that predicts the state of user's next actions, exploiting the HMM (Hidden Markov Model) on user profile data stored in the ubiquitous home network. The HMM, recognizes patterns of sequential data, adequately represents the temporal property implicated in the data, and is a typical model that can infer information from the sequential data. The proposed algorithm uses the number of the user's action performed, the location and duration of the actions saved by "Activity Recognition System" as training data. An objective formulation for the user's interest in his action is proposed by giving weight on his action, and change on the state of his next action is predicted by obtaining the change on the weight according to the flow of time using the HMM. The proposed algorithm, helps constructing realistic ubiquitous home networks.

• Convergence Security Journal
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• v.10 no.4
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• pp.69-76
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• 2010

public certification is some kind of electric ID which can prove the valid user, based on open KEY. usually it had been used in the field of government complaint, e-commerce, financial. but recently it expands the its use range through computerization of work process of diversity fields such as e-sports, property, medical industry. because of this reason, importance for user certificate process is gradually rose. The purpose of this paper is looking at the method for user certification of public certificates and draw a way for enforce the user certification process by Vulnerability Analysis. To draw the alternative we study the Authentication Principle and policy structure of public certification system by researching references, has drew the limitation for policy of certification. we provide the guideline to enforce the user certification through conclusion which has been drew from previous step.

• Journal of Information Technology Services
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• v.13 no.4
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• pp.289-308
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• 2014

Mobile instant messaging (MIM) has been widely used in modern society due to its portability, speed and ease of use. In addition to simple text-based messaging, mobile instant message has now expanded to include graphics, images, and video. Many instant message service providers attempt to differentiate their service by providing an unique emoticon. Therefore, understanding the factors that affecting the continuous usage of emoticon is essential to capture users' interest. There is relatively little study on emoticon in information systems field. Hence, this study attempts to explore the continuous usage of emoticon through exploring the property of emoticon and usage motivation of emoticon. Based on the results, this study attempts to demonstrate practical implication of marketing on understanding user interest to mobile instant messenger service provider.