• Journal of KIISE
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• v.43 no.1
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• pp.96-105
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• 2016

Recently, social network services have changed by moving towards an open platform where, as well as simply allowing the building of relationships among users, various types of information can be generated and shared. Since existing user reputation management methods evaluate user reliability based on user profiles, explicit relations, and evaluation, they are not suitable for determining user reliability on social media due to few explicit evaluation. In this paper, we analyze social activities on social media and propose a new user reputation management method that considers implicit evaluation as well as explicit evaluation. The proposed method derives positive and negative implicit evaluation from social activities, and generates user reputation information by field in order to consider user expertise. It also considers the number of users that participate in evaluation in order to measure user influence. As a result, it generates the reputation information of users who have no explicit evaluation and creates user reputation information that is more suitable for social media.

• The KIPS Transactions:PartA
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• v.13A no.7 s.104
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• pp.599-606
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• 2006

As the P2P service does not have any administration authorities that are able to manage the behavior of participants and control the malicious users, malicious user can give harm to legitimate users for the benefit of themselves. To perform the secure transaction with new members who did not have past experiences on transaction, service users can differentiate malicious users and legitimate users by referring to the reputation information that provided by users having past experience. However, users can intentionally give false evaluation to other users on Performed transaction. We call these users as 'liar'. In this Paper, we propose a new reputation system for liar reduction to guarantee an accuracy on reputation information.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.2
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• pp.35-47
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• 2004

Though P2P network systems are widely used, not so much research has been done on security issues. One of the serious problem in P2P network is the authentication problem. To resolve this problem, we introduce a new concept, a "self-reputation system" in which a user manages her own reputation. We define self-reputation systems by presenting several requirements. We also give one instance of self-reputation system. The proposed instance satisfies the requirement including the prevention of erasing and the platform independence.ependence.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.363-365
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• 2012

최근 빠르게 확산되고 있는 소셜 네트워크 서비스(Social Network Service)는 사용자의 인맥을 관리하며 새로운 인맥을 형성하는 것을 목표로 한다. 또한 사용자들이 자신의 관심사에 관한 지식이나 정보를 공개함으로써 정보의 효율성을 높이고 다른 사용자들에게 정보를 전파한다. 하지만 현재의 소셜 네트워크 서비스는 새로운 인맥을 형성하는 것보다 실제 사회에서의 인맥을 가상의 공간에서도 유지하고 관리하여 실제로 만나지 않더라도 관계를 유지할 수 있도록 하는 용도로 사용되어 소셜 네트워크의 목표를 달성하지 못하고 있다. 하지만 특정한 공간의 동일한 관심사를 가진 사람들 간의 제한적 정보 공유는 소셜 네트워의 단점을 보안하고 궁극적 목표를 달성할 수 있다. 또한 특정 관심사를 기반으로 그룹을 생성함으로써 정보의 신뢰도를 높이며 새로운 인맥을 형성에도 효과적 일 것이다. 하지만 이러한 네트워크는 모바일 환경의 특징으로 인해 빠르게 변화할 수 있으며 위치를 기반으로 특정 공간의 다른 사용자들과 통신함으로 완전히 새로운 인맥을 형성하게 된다. 그러므로 안전하게 신뢰관계를 구축하기위해 사용자의 평판 관리가 필요하다. 본 논문에서는 소셜 네트워크에서 동일한 관심사를 가진 폐쇄적 정보공유에서의 악의적 노드의 고립을 위한 평판 메커니즘을 제안한다.

• Journal of the HCI Society of Korea
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• v.13 no.2
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• pp.21-29
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• 2018

Continuous use of SNS with having SNS fatigue influences users mentally as well as physically. Although it is reported that they eventually leave SNS due to experience of fatigue, the determinants of SNS fatigue have not been discovered yet. Thus this study aims to find the psychological factors causing SNS fatigue. This study (1) found out the factors causing SNS fatigue, and (2) explored the relationships between the factors and intentions to discontinue/continue to use SNS. Findings of the study suggested that there are seven types of determinants: Sense of relative deprivation, Relationship concern, Management burden, Information overload, Privacy concern, Reputation concern(after posting), Reputation concern(before posting). It is also found that sense of relative deprivation negatively predicted the intention to keep using SNS while management burden, reputation concern(before posting) predicted positively. Furthermore, the sense of relative deprivation and information overload positively predicted the intention to discontinue using SNS while reputation concern(before posting) predicted negatively. This research examined how the determinants of SNS fatigue affect the intentions to keep/stop using SNS from the two different points of view. The determinants of SNS fatigue experienced by SNS viewers influenced them to have intentions to stop using it, whereas those felt by SNS writers affected them to keep using it.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.410-415
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• 2013

Recently, as Internet enters WEB 2.0, many social network services through such as Facebook, Twitter and Youtube appeared. In these social network sites, users can easily make friends, join groups and access others personal information. Therefore, a malicious user can easily gather information of others. In order to protect user's personal information from the unauthenticated users, we propose privacy protection mechanism based on key assignment and user's trust level. A master-key is generated for each users and is segmented into a core-key and several sub-key. The master-key stores at the information owner's side and the sub-key will be distributed to requestor according to the relation and trust level. At last, in order to proof the efficiency, the performance of our proposed mechanism is compared with those of existing mechanisms.

• Proceedings of the Korean DIstribution Association Conference
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• 2006.05a
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• pp.103-115
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• 2006

중국은 세계 무역기구에 가입하면서 세계경제에서 차지하는 위치가 강화되고 디지털 경제체제에 편입되면서 산업구조를 고부가가치 산업으로 개편하고 있다. 동안 상대적으로 외국기업에 대해 폐쇄적이었던 중국의 유통시장은 2006년부터 전면개방이 시작될 것으로 전망되고 있다. 그러나 중국전자상거래 시장에서 정보 기초화와 물류배송 금융체계의 문제는 나날이 안정화되어 온라인 구매환경은 나아지고 있으나, 오히려 해마다 인터넷쇼핑물 구매율의 하락은 온라인 쇼핑몰 상거래에 대한 불신 문제가 그대로 남아있음을 알 수 있다. 따라서 본 연구에서는 중국의 소비자수준에서의 온라인 구매가 활성화되지 못하는 주요 장애요인으로써 불신(distrust)을 제기하고자 하며 신뢰를 신뢰와 불신의 2차원으로 파악하여 각각의 차원(신뢰와 불신)이 마케팅 성과에 차별적으로 공헌하고 있음을 밝히고자 한다. 본 연구에서 선행변수로 상호작용, 지각된 평판, 정보유용성, 지각된 보안위험, 지각된 거래위험을 설정했으며 매개변수로는 신뢰와 불신을, 결과 변수로는 관계몰입과 구매의도로 구성하였다. 결과에서는 온라인 맥락에서는 신뢰와 불신의 선행요인이 온라인 쇼핑몰에 대한 관계몰입과 구매의도에 서로 차별적으로 공헌한다는 것을 밝혔다. 이는 기존의 신뢰를 2차원으로 구분하여 신뢰와 불신으로 분리하여 관리하는 것이 필요하다는 것을 시사한다고 할 수 있다.

• The Journal of Society for e-Business Studies
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• v.24 no.3
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• pp.1-18
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• 2019

Due to the great advances in e-Marketplace and changes in type of items purchased from the online market, it has been dramatically increased the demand of the storage and transportation under the special conditions such as restricted temperature. Especially, the cold chain needs the way to transparently measure and monitor the entire network in realtime because it has a very complicated structure and requires totally different criteria at the every different steps and items. In this research, it has been presented the performance evaluation metrics to make contract using service level agreement (SLA), the way to apply the smart contract based on blockchain, the structure of blocks, service platform and application in order to build cold chain which can prevent the risk factors by measuring and sharing information in realtime using block chain technology. In addition, we have proposed the way to store the measured performance and reputation of each player in the block using smart contract based on SLA. With the presented framework, all players including service providers as well as users can secure the information for making the rational decisions. When the service platform is actually built and operated, it seems possible to secure the information in transparently and realtime. Also, it is possible to prevent the risk factors or prepare the preemptive plans to react on them.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.573-579
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• 2019

The purpose of this study is predicted easily the entrance surface dose (ESD) in chest digital radiography. We used two detector type such as flat-panel detector (FP) and IP (Imaging plate detector). ESD was measured at each exposure condition combined tube voltage with tube current using dosimeter, after attaching on human phantom, it was repeated 3 times. Phantom images were evaluated independently by three chest radiologists after blinding image. Dose-area product (DAP) or exposure index (EI) was checked by Digital Imaging and Communications in Medicine (DICOM) header on phantom images. Statistical analysis was performed by the linear regression using SPSS ver. 19.0. ESD was significant difference between FP and IP($85.7{\mu}Gy$ vs. $124.6{\mu}Gy$, p=0.017). ESD was positively correlated with image quality in FP as well as IP. In FP, adjusted R square was 0.978 (97.8%) and linear regression model was $ESD=0.407+68.810{\times}DAP$. DAP was 4.781 by calculating the $DAP=0.021+0.014{\times}340{\mu}Gy$. In IP, adjusted R square was 0.645 (64.5%) and linear regression model was $ESD=-63.339+0.188{\times}EI$. EI was 1748.97 by calculating the $EI=565.431+3.481{\times}340{\mu}Gy$. In chest digital radiography, the ESD can be easily predicted by the DICOM header information.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.129-141
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• 2006

The vertical soil pressure developed in the granular layer of asphalt pavement system is influenced by various factors, including the wheel load magnitude, the loading speed, and asphalt pavement temperature. This research observed the distribution of vertical soil pressure in pavement supporting layer by investigating measured data from soil pressure gage in the KHC Test Road. The existing specification of subbase and subgrade compaction was also evaluated with measured vertical pressure. The finite element analysis was conducted to verify the accuracy of results with measured data because it can maximize research capacity without significant field test. The test data was collected from A5, A7, A14, and A15 test sections at August, September, and November 2004 and August 2005. Those test sections and test data were selected because they had best quality. The size of influence area was evaluated and the vertical pressure variation was investigated with respect to load level, load speed, and pavement temperature. The lower speed, higher load level, and higher pavement temperature increased the vertical pressure and reduced the area of influence. The finite element result showed the similar trend of vertical pressure variation in comparison with measured data. The specification of compaction quality for subbase and subgrade is higher than the level of vertical pressure measured with truck load so that it should be lurker investigated.