• Journal of the Korea Society of Computer and Information
• /
• v.25 no.9
• /
• pp.101-108
• /
• 2020

Recommender system is a must-have feature of e-commerce, since it provides customers with convenience in selecting products. Collaborative filtering is a widely-used and representative technique, where it gives recommendation lists of products preferred by other users or preferred by the current user in the past. Recently, researches on the recommendation system using deep learning artificial intelligence technologies are actively being conducted to achieve performance improvement. This study develops a collaborative filtering based recommender system using restricted Boltzmann machines of the deep learning technology by utilizing user ratings. Moreover, a learning parameter update algorithm is proposed for learning efficiency and performance. Performance evaluation of the proposed system is made through experimental analysis and comparison with conventional collaborative filtering methods. It is found that the proposed algorithm yields superior performance than the basic restricted Boltzmann machines.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.3A
• /
• pp.213-220
• /
• 2009

Cooperative diversity is a promising technique for range extension and diversity increase without the use of multiple transmit antennas at the user equipment. In this paper, we propose a cooperative hybrid automatic repeat request relay method with adaptive retransmission to increase the throughput when the SNR of a source user is low. In the proposed method, the source user transmits the first segment of a codeword to relay users and a base station. If the base station fails to recover the information from the received packet, it requests the source or some relay users to retransmit the packet previously sent. In addition, the retransmission type of a selected user is chosen from repetition or incremental redundancy according to the quality of systematic bits in a turbo codeword. Simulation results show that the proposed method improves the throughput compared to conventional methods, and the improvement is significant when the source user has a low SNR.

• The Journal of the Korean dental association
• /
• v.22 no.10 s.185
• /
• pp.855-860
• /
• 1984

국산 세치제와 잇솔이 갖추어야 할 기본요건과 개발방향이 제시된 세미나가 지난해에 이어, 지난 7월 14~15일 양일간에 걸쳐 속리산 관광호텔에서 구강보건학계와 럭키ㆍ부광ㆍ태평양등 국내 3대 세치제 제조회사의 52명이 참석한 가운데 서울치대 예방치학교실 주최로 개최되었다. 총 13개 연제가 발표된 이번 세미나에서는, 국민 복지를 빨리 증진시키기 위하여, 기업간의 건전한 경쟁을 유도하고, 기술개발을 촉진하며, 국산품의 품질 개선, 가격인하, 국제경쟁력의 신장등, 정부의 기본방향을 재확인하는 동시에 거시적이고 원시적인 안목으로 볼때 기술개발을 위한 산학활동과 선업간의 협력은 산업발전을 통하여 국민복지 증진에 분명히 기여할 수 있음을 강조한 서울치대 김종배교수의 주제 발표와 세치제의 주요작용, 세치제의 abrasiveness 및 polishing 효과와 용어의 정의, 개인에 적합한 세치제의 선택방법, Monofluorophosphate와 plaque 및 타액의 상호작용, 세치제의 선호변인 분석, 세치제 광고문안상의 문제점, 세치제의 전망, 세치제의 전망, 세치제 개발의 제요소, 세치제의 검정 기준과 과정, 잇솔의 기본요건과 시판잇솔의 규격, 잇솔의 강모형태와 탄력성에 관한 이론적 고찰, 개인에 적합한 강모강도를 가진 잇솔의 선택방법, 「A study on the F'ion concentration of commercial dentifrices」에 대해 폭넓고 진지한 토의가 있었다. 다음은 이날 발표된 내용을 요약정리한 것이다.

• Proceedings of the Technology Innovation Conference
• /
• 2005.02a
• /
• pp.200-219
• /
• 2005

현재 홈네트워킹의 솔루션으로 제기되고 있는 것은 이더넷(Ethernet), 전화선(Phone line), 전력선(PLC), 무선랜(Wireless LAN), 블루투스(Blue tooth) 등 다양하다. 그러나 국내 홈네트워킹 시장과 기술의 진행 방향 및 잠재 시장 전망에 대한연구가 부족한 현실에서 시장 참여자들의 불 확실성은 높을 수 밖에 없다. 이에 어떤 기술이 홈네트워킹 시장을 주도할 지를 전망하는 것이 무엇보다 시급한 과제가 되고 있다. 따라서 본 연구에서는 홈네트워킹 유선 전송 기술분야에서 유력한 규격으로 예상되는 PLC를 중심으로 홈네트워킹의 수요를 예측하고자 한다. 홈네트워킹 시장은 홈네트워킹 장치들이 Built-in 형태로 보급되는 신규주택과 소비자의 선택에 의해 홈네트워킹 장치들이 설치되는 기존 주택 시장으로 나누어 질 수 있다. 본 연구에서는 기존 주택 시장을 대상으로 컨조인트 방법을 통한 소비자의 선호 구조를 홈네트워킹을 구현시키는 각 기술에 대한 (기술)로드맵과 결합하여 동적인 소비자의 선택을 관찰함으로써 각 기술이 확산되는 과정을 살펴볼 것이다. 추가적으로 PLC의 기술적 특징들을 가상적으로 변화시켜가면서 다른 기술과의 경쟁관계를 살펴봄으로써 PLC의 기술개발 전략에 시사점을 도출할 것이다. 본 연구를 통해 홈네트워킹의 관련 실무자에게는 향후 홈네트워킹 시장 진입이나 제품 개발, 기술 협력 제휴시 유용한 자료가 될 것으로 보인다. 또한 정부의 정책담당자들에게는 홈네트워킹 확산의 장애요인 해소를 위한 정책 가이드라인을 제공할 수 있을 것으로 기대하고 있다.

• Journal of KIISE
• /
• v.43 no.1
• /
• pp.119-125
• /
• 2016

Cognitive radio technology can allow secondary users (SUs) to access unused licensed spectrums in an opportunistic manner without interfering with primary users (PUs). Spectrum sensing is a key technology for cognitive radio (CR). However, few studies have examined energy-efficient spectrum sensing in cognitive radio sensor networks (CRSNs). In this paper, we propose an energy-efficient cooperative spectrum sensing nodes selection scheme for cluster-based cognitive radio sensor networks. In our proposed scheme, false alarm probability and energy consumption are considered to minimize the number of spectrum sensing nodes in a cluster. Simulation results show that by applying the proposed scheme, spectrum sensing efficiency is improved with a decreased number of spectrum sensing nodes. Furthermore, network energy efficiency is guaranteed and network lifetime is substantially prolonged.

• Journal of Distribution Science
• /
• v.5 no.2
• /
• pp.55-78
• /
• 2007

Northeast Asia is one of the regions which have been developing so rapidly. Yellow sea, located between Korea and China, became a very important logistical zone because of its huge volume of cargo and big passenger traffic. These two countries continuously are enlarging their port facilities such as berths, container yards, storage capacity and their information system in this the Pan Yellow sea area. Two countries also introduce many new liner routes and car-ferry shipping services. Therefore there must be a severe competitions and conflicts among the countries and their companies and ports as well. Some experts worry about the over capacity of port and logistics facilities. This paper investigated the current conditions of Korea-China shipping route, container and car-ferry route, and found out the problems and tasks, with the support of many experts. There are so many alternatives and strategies to solve and rationalize the shipping route and the problems of ports of two countries. This paper suggest many strategies connecting with marketing 4Ps. As port service is also a kind of service product, we can categorize the strategies into 4Ps suggested by McCarthy. And this paper classify all these alternatives into 3 dimensions. There are competitive strategies, cooperative strategies and coopetition strategies. This paper propose some directions and ideas for adopting the strategy in the port and logistical topics between Korea and China, suggesting 3 dimensions of strategies. After this paper, many diagnoses and practical investigations should be executed to introduce optimal solutions and minimize the additional cost.

• Journal of Korean Society of Transportation
• /
• v.29 no.1
• /
• pp.81-93
• /
• 2011

This research deals with the multi-modal continuous network design problem to resolve the transportation policy problems for constructing and operating transportation facilities with considering the mutual decision-making process between transportation operator and user in the multi-modal network. Particularly, in the consideration of changes in travel pattern between transport modes due to the changes in transportation policy, road network for passenger car and transit network for public transportation are considered together. In the development of network design model, more rational Stackelberg equilibrium(cooperative game) rather than more general Nash equilibrium(non-cooperative game) approach is used and sensitivity analysis considering transport mode is used. A multi-modal continuous network design model in this study is developed for the arbitrary continuous network design parameters(${\epsilon},\hat{\epsilon},p$) of transportation policy decisions. As examples of application and evaluation for these design parameters, the developed model is applied to calculate 1)the optimal capacity of road link in the road transport policy, 2)the optimal frequency of transit line in public transport policy and 3)the optimal modal split in transport modal share policy.

• The Journal of the Korea Contents Association
• /
• v.18 no.6
• /
• pp.63-72
• /
• 2018

This study was conducted to explore the impact of learning strategies on the level of participation in the online collaborative learning process. To do this, We studied 91 students who took professorship courses at A university in the Seoul metropolitan area. At the beginning of the semester, the learning strategies were measured through MSLQ, rehearsal, elaboration, organizing, critical thinking, metacognition, learning management, effort control, peer learning, and seeking help. Next, cooperative tasks were carried out to measure the interaction, and group composition consisted of 4-5 persons. The level of participation was measured by scores given to the messages created for interaction. The process of collaborative learning was divided into the steps of identifying learning goals, learning plans, performing individual learning, sharing learning results, and writing reports. The effects of learning strategies on participation level were analyzed through multiple regression analysis (stepwise selection method). As a result, the learning goal step influenced the highest level of metacognition, and the learning plan is the management of the learning time, the demonstration of the learning execution, the adjustment of the effort, the acquisition of help, the collegial learning, Writing was influenced by organization, elaboration, critical thinking, and critical thinking, metacognition, and elaboration.

• Land and Housing Review
• /
• v.6 no.2
• /
• pp.79-88
• /
• 2015

North Korean leader Kim, Jung-Il visited Beijing, China, May 2010, when he made a common recognition with Chinese President Hu Jintao on construction of the Rasun SEZ and the Hwanggumpyong-Wyhwado SEZ for development of Economic cooperation between N.Korea and China and accelerating establishment of SEZs in N.Korea. However, after N.Korea's third nuclear test on Feb. 2013, the relationship between N.Korea and China became a little worse. Recently, three nations' border region near Rasun in N.Korea is reconsidered that it is very important place for collaboration between and among 2, 3 or 4 countries, S.Korea, N.Korea, China and Russia. This thesis examined these changes of cooperation and plans among the countries near the border region and proposed some measures for participation of S.Korea on the projects in the Rasun region.

• Journal of the Korean Society for Library and Information Science
• /
• v.53 no.1
• /
• pp.83-108
• /
• 2019

This study investigated South Korean citizens' political communication and deliberation through Twitter during the 2014 General Election, focusing on influential opinion leaders' political information behaviors. Individual semi-structured interviews were administered with 13 opinion leaders using the multiple interview modes of email interviews, Skype interview and face to face interviews. Through the analytical lens of the theory of Information Worlds, the chosen social types and social norms of opinion leaders impacted their political information behaviors, including how they assessed, shared, exchanged, or avoided information, and, in turn, created boundaries between and around their information worlds that allowed for both conflict and synergy.