• International Journal of Contents
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• 제13권1호
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• pp.53-61
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• 2017

Recently, the Social Internet of Things (IoT), the follow-up of the IoT, has been studied to expand the existing IoT services, by integrating devices into the social network of people. In the Social IoT environment, humans, devices and digital contents are connected with social relationships, to guarantee the network navigability and establish levels of trustworthiness. However, this environment handles massive data, including social data of humans (e.g., profile, interest and relationship), profiles of IoT devices, and digital contents. Hence, users and service providers in the Social IoT are exposed to arbitrary data when searching for specific information. A study about the recommender system for the Social IoT environment is therefore needed, to provide the required information only. In this paper, we propose the Social correlation group based Recommender System (SRS). The SRS generates a target group, depending on the social correlation of the service requirement. To generate the target group, we have designed an architecture, and proposed a procedure of the SRS based on features of social interest similarity and principles of the Collaborative Filtering and the Content-based Recommender System. With simulation results of the target scenario, we present the possibility of the SRS to be adapted to various Social IoT services.

• Journal of Positioning, Navigation, and Timing
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• 제6권2호
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• pp.53-57
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• 2017

eLoran refers to a terrestrial navigation system using high-power low-frequency signals. Thus, it can be regarded as a positioning, navigation and timing (PNT) system to back up a global navigation satellite system (GNSS) or an alternative to GNSS. South Korea is vulnerable to interference such as GNSS jamming in particular. Therefore, South Korea has made an effort to develop an independent navigation system through eLoran system. More particularly, an eLoran testbed has been developed to be used in the northwest sea area and research on applicability of eLoran in South Korea has been underway. The present study analyzes expected performance of eLoran according to locations of newly built eLoran transmitting stations as part of the eLoran testbed research. The performance of eLoran is analyzed in terms of horizontal position accuracy, and horizontal dilution of precision (HDOP) information was used since it affects accuracy significantly. The target service areas of the eLoran testbed are Incheon and Pyeongtaek Ports, and the required target performance is positioning accuracy of 20 m position within 30 km coverage of the target service area.

• 산업경영시스템학회지
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• 제46권2호
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• pp.109-115
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• 2023

This paper studied the problem of determining the optimal inventory level to meet the customer service target level in a situation where the customer demand for each branch of a nationwide retailer is uncertain. To this end, ISR (In-Stock Ratio) was defined as a key management indicator (KPI) that can be used from the perspective of a nationwide retailer such as Samsung, LG, or Apple that sells goods at branches nationwide. An optimization model was established to allow the retailer to minimize the total amount of inventory held at each branch while meeting the customer service target level defined as the average ISR. This paper proves that there is always an optimal solution in the model and expresses the optimal solution in a generalized form using the Karush-Kuhn-Tucker condition regardless of the shape of the probability distribution of customer demand. In addition, this paper studied the case where customer demand follows a specific probability distribution such as a normal distribution, and an expression representing the optimal inventory level for this case was derived.

• 한국정보과학회논문지:시스템및이론
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• 제33권10호
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• pp.709-721
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• 2006

지상파, 위성파, 케이블 방송 같은 기존의 방송환경은 시청자 취향에 상관없이 일방적인 단방향 방송 서비스를 제공해 왔다. 하지만, 최근에는 광대역 통신망을 통한 다양한 미디어 전송이 가능하게 되었다. 또한, 방송 환경에서 양방향 통신이 가능하게 됨으로써 장르, 시청 시간대, 배우 등 시청자의 선호도를 반영한 방송 서비스가 중용한 응용으로 대두되고 있다. 따라서, 기존의 방송환경에서 시청자의 선호도를 반영한 맞춤형 방송 서비스가 중요한 방송 서비스의 하나가 될 수 있다. 본 논문에서는 표적광고를 위한 새로운 시도로써 맞춤형 방송 서비스 응용 중 하나인 시청자 프로과일 추론을 통한 표적 광고 방법을 소개한다. 제안된 시청자 프로파일 추론 알고리즘은 시청자의 TV 시청 데이타(TV Viewing history data) 분석을 통해 시청자의 성별 및 연령대를 예측한다. 예측된 시청자의 성별 및 연령대를 바탕으로 TV Anytime 메타데이타를 이용한 표적 광고 선별 방법을 통하여 광고를 선택하게 된다. 제안된 표적 광고 시스템은 시청자 프로파일 추론 알고리즘과 표적 광고 선별 방법을 이용하여 구성되어 있으며, 실제 TV 시청 데이타를 이용하여 제안된 표적 광고 시스템의 실험 결과를 제시한다.

• 디지털산업정보학회논문지
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• 제10권3호
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• pp.181-196
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• 2014

Cloud computer technology currently provides diverse services based on a comprehensive environment ranging from hardware to solution, network and service. While the target of services has been extended from institutions and corporations to personal infrastructure and issues were made about security problems involved with protection of private information, measures on additional security demands for such service characteristics are insufficient. This paper proposes a multi-session authentication technique based on the characteristics of SaaS (Software as a Service) among cloud services. With no reliable authentication authority, the proposed technique reinforced communication sessions by performing key agreement protocol safe against key exposure and multi-channel session authentication, providing high efficiency of performance through key renewal using optimzied key table. Each formed sessions have resistance against deprivation of individual confirmation and service authority. Suggested confirmation technique that uses these features is expected to provide safe computing service in clouding environment.

• Journal of Korea Trade
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• 제27권2호
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• pp.61-76
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• 2023

Purpose - The digital service trade has become an important driver of the global service trade. The main purpose of this study is to explore the influencing factors of digital service exports from China and Korea to RCEP sample countries respectively, and to comprehensively study the export potential of China and Korea to RCEP countries, so as to provide theoretical guidance and a decision-making reference to promote digital service trade exports and digital economy development in China and Korea. Design/methodology - First, the stochastic frontier gravity model was improved by introducing nonefficiency factors affecting digital services trade, extending the gravity model of traditional services trade exports to digital services trade exports. Secondly, the panel data of China and Korea for the eight sample countries of RCEP from 2011 to 2021 were adopted for the empirical analysis of digital service export potential by a stochastic frontier model. Findings - China's economic growth plays a role in increasing China's digital service trade exports, while Korea's economic growth does not play a significant role in increasing Korea's digital service trade exports. However, the economic growth of trading partner countries can play a significant role in boosting the digital service trade in both China and Korea, and comparison shows that Korea has higher resilience in the digital services trade than China. In addition, the market size of target countries plays a positive role in promoting the digital service trade exports of both China and Korea, and the increase in the value-added share of services in target countries will lead to a decrease in the digital service trade exports of both China and Korea. Originality/value - This study is innovative in terms of research perspective and method. Academic research on the export potential of international trade has been extensive, but most studies are based on the perspective of the goods trade, fewer studies are based on the perspective of the service trade, and there are almost no studies based on the perspective of digital service trade. There is a gap based on the comparative analysis of the export potential of the digital service trade between China and Korea. This study extends the gravitational model of traditional service trade exports to digital service trade exports to comparatively analyze the export potential of China and Korea to RCEP countries. This study addresses this limitation by analyzing a comparative analysis of the digital service trade export potential of China and Korea.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.441-445
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• 2004

In this paper, we deal with an inventory model of a multi-stage, serial supply chain system where a single product type and nonstationary customer demand pattern are considered. The retailer and suppliers place their orders according to an echelon-stock based replenishment control policy. We assume that the suppliers can access online information on the demand history and use this information when making their replenishment decisions. Using a reinforcement learning technique, the inventory control parameters are designed to adaptively change as the customer demand pattern is altered, in order to maintain a given target service level. Through a simulation based experiment, we verified that our approach is good for maintaining the target service level.

• 한국정보통신학회논문지
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• 제21권9호
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• pp.1788-1795
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• 2017

본 논문에서는 육/해상에서 제공 가능한 다양한 서비스를 통해 항해사의 의사결정을 지원함으로써 해양 안전을 확보하기 위한 연구의 일환으로 ARPA 혹은 ATA 장비가 탑재되어 있지 않는 선박에 CPA/TCPA 정보를 제공하기 위한 서비스를 제안한다. 제안 서비스를 검증하기 위하여 실제 선박을 대상으로 실험을 수행하기에는 많은 어려움이 있기 때문에 본 논문에서는 시나리오 기반의 시뮬레이터인 SiNAS 및 CPA/TCPA 정보 제공 소프트웨어를 활용하여 유용성을 평가한다. 이를 위해 검증 목적에 적합하도록 시뮬레이션 시나리오를 명세한 후, 다양한 경력을 가진 12명의 항해사를 선정하여 시뮬레이션을 수행한다. 또한, 임무 성공 여부, 충돌 위험 선박과의 최근접 거리, 충돌 위험 선박을 인지하는데 까지 걸린 시간, 인지한 후 회피 조치를 취한 시간 등을 기반으로 시뮬레이션 결과를 분석하며, 유효성, 효율성, 만족성의 세 가지 요소를 기준으로 제안 서비스의 유용성을 평가한다.

• 한국조경학회:학술대회논문집
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• 한국조경학회 2022년도 추계학술대회 논문집
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• pp.31-33
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• 2022

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2011년도 추계학술대회
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• pp.727-745
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• 2011

Courier and logistics services such as customer contact employees (customer-contact employee) of the attitudes and behavior of the customer satisfaction level of service quality evaluation and a very big impact. In this study, using a typical customer contact employees, and to target the delivery service industry employees the organization's service orientation and customer orientation by examining the impact on the quality of companies within the organization for growth and development needs and the importance of service orientation will be trying out for. The results of this study can be summarized as follows. First, the chief executive of the organization to configure a service orientation and a detailed understanding of the factors that determine this by managing the organization to effectively come up with a way to make and ultimately the organization's service orientation, organizational culture can be positioned as effort should be taken. Second, service companies through regular training and education to maintain a certain level of service quality should be. Third, the service organization's service orientation is not a fad or a means of sustain and develop the company's survival strategy is to get out. To do this, good communication between the field and management can be achieved by a variety of channels to be established, and management's willingness to provoke sympathy for the employees should be provided.