• The KIPS Transactions:PartC
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• v.10C no.7
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• pp.943-954
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• 2003

The mobile telecommunication system has been growing exponentially after 1990s due to the high population in a city and the growth of mobile user. In this time, the current mobile system mainly concentrates on the voice communication. However, in the next generation, mobile users want to get very diverse services via mobile terminal such as the Internet access, web access, multimedia communication, and etc. For this reason, the next generation system, such as the UMTS (Universal Mobile Telecommunication Services) system, has to support the packet data service and it will play the major role in the system. By the way, since the Web service is based on TCP, most of the Internet traffic TCP traffic. Therefore, efficient transmission of TCP traffic will take very important role in the performance of packet data service. There are many researches about improving TCP performance over wireless network. In those schemes, the UMTS system adapts the link layer retransmission scheme. However, there are rarely studies about the exact performance of the link layer retransmission scheme in the face of dynamic changes of wireless environment over the UMTS system. The dynamic changes of wireless environment, such as wireless bandwidth, can degrade TCP performance directly. So, in this paper, we simulate and analyze the TCP performance in the UMTS system with dynamic wireless environments. Then, we propose a simple scheme for minimizing TCP performance degradation. As a result of simulation, we can find that when wireless environment is changed dynamically, the probability of TCP timeout is increased, and the TCP performance is degraded very much. In this situation, the proposed simple scheme shows good performance. It saves wireless resources and reduces the degradation of TCP performance without large overhead of the base station.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.668-675
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• 2003

In this paper, we propose an enhanced p-cycle (preconfigured protection cycle) scheme for WDM mesh networks with QoS constraints. In the previous researches on p-cycle, it is assumed that user's connection has a hi-directional connectivity and the same bandwidth on both direction. Therefore it is difficult to apply p-cycle based link protection to uni-directional connections for multicasting or asymmetric broadband multimedia communications with hi-directional connectivity. And it didn't consider QoS of backup path. We enhanced the p-cycles to accomodate uni-directional connections for multicasting or asymmetric bandwidth communications with hi-directional connectivity. And we propose a selection procedure of p-cycle to assure QoS of backup path. We were able to reduce a required backup bandwidth by applying a uni-directional p-cycle concept to asymmetric broadband multimedia communication environment. The proposed p-cycle selection procedure is applied to the U.S. sample network to evaluate whether the configured p-cycles can support QoS constraint of working path and backup path.

• Journal of Korea Port Economic Association
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• v.35 no.2
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• pp.109-126
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• 2019

The Panmunjom Declaration adopted by the leaders of South and North Korea on April 27, 2018, has created an environment conducive for peace and cooperation in the Korean Peninsula. In the June of last year, South Korea has joined the Organization for Cooperation between Railways (OSJD). The membership of OSJD has established a solid foundation for restoring a multimodal logistics system that connects the Korean peninsula to Eurasia countries, including China and Russia. In this paper, a questionnaire survey targeting working-level experts was conducted to find the barriers in constructing multimodal logistics that efficiently connect the port-continental railways of the Korean peninsula and the Eurasian nations. Survey items were divided into five categories-border crossing procedures, technology, facilities, operation, and government support. As a result, among the most important problems of international multimodal logistics in Eurasia that need to be solved on priority include improving transshipment facilities, eliminating inspection carried out at every country for transit, simplifying documents for customs clearance, and minimizing the changes in freight rates. In conclusion, for vitalizing the connection between the Korean peninsula and the continental railways, it is necessary to develop a transshipment system to facilitate the changes in tracks at the borders by making a joint effort with the international community. Second, railway and operational systems in South Korea, North Korea, China, and Russia should be standardized. Third, international cooperation among South Korea, North Korea, China, and Russia is essential for simplifying customs clearance at borders, priority departure of domestic cargo, sharing information about the changes in freight rates, and so on. Finally, the government should come up with measures to secure the quantity of cargo required to form block trains, while developing new business models.

• Journal of Industrial Convergence
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• v.22 no.4
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• pp.1-9
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• 2024

Smart factories represent production facilities where cutting-edge information and communication technologies are fused with manufacturing processes, reflecting rapid advancements and changes in the global manufacturing sector. They capitalize on the integration of robotics and automation, the Internet of Things (IoT), and the convergence of artificial intelligence technologies to maximize production efficiency in various manufacturing environments. However, the smart factory environment is prone to security threats and vulnerabilities due to various attack techniques. When security threats occur in smart factories, they can lead to financial losses, damage to corporate reputation, and even human casualties, necessitating an appropriate security response. Therefore, this paper proposes a security authentication mechanism for safe communication in the smart factory environment. The components of the proposed authentication mechanism include smart devices, an internal operation management system, an authentication system, and a cloud storage server. The smart device registration process, authentication procedure, and the detailed design of anomaly detection and update procedures were meticulously developed. And the safety of the proposed authentication mechanism was analyzed, and through performance analysis with existing authentication mechanisms, we confirmed an efficiency improvement of approximately 8%. Additionally, this paper presents directions for future research on lightweight protocols and security strategies for the application of the proposed technology, aiming to enhance security.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.86-86
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• 2018

본 연구는 한국의 도시재생과 스마트 물 관리의 정책 분석을 위하여 도시재생과 스마트 물 관리의 등장 배경, 주요 현안 및 연계성을 모색하고 도시재생방안으로서 스마트 물 관리체계의 가능성을 검토하는 것을 목적으로 한다. 1950년대의 도시재건(Urban Reconstruction)과 1970~80년대의 도시재개발(Urban Renewal, Urban Redevelopment) 등의 정비 사업은 물리적 환경정비에 초점을 맞추었다. 그러나 1990년대 환경문제가 세계적 이슈로 등장하면서 교외지역 난개발 문제에 대한 대응책이 필요하게 되었고 도시의 물리 환경적, 산업 경제적, 사회 문화적 측면을 부흥시키는 도시재생 접근법이 출현하였다. 한국 정부는 2017년부터 시작한 '도시재생 뉴딜사업'의 일환으로 스마트 기술을 적용한 도시재생사업을 통해 스마트도시 선도국가 도약과 세계적 흐름에 부합하는 도시성장을 기대하고 있다. 1980년대 초 등장한 스마트 기술은 2000년대 들어와 스마트 도시, 스마트 인프라, 스마트 그리드 등의 분야로 확대, 진보하였다. 물 분야의 스마트 기술은 2009년 스마트워터그리드 이니셔티브(Smart Water Grid Initiative)의 발족과 함께 IBM, CISCO, Intel 등의 IT 기반 물 관리 워킹그룹 형성, Suez, Veolia, Siemens 등 수처리 기업의 스마트워터그리드 분야 진출 모색과 함께 발전하기 시작하였다. 이후 2012년 유엔 스마트 물 관리 포커스 그룹(ITU-T SG 5)의 스마트 물 관리 표준화 연구가 착수되었고 한국은 국토교통부 건설교통기술 연구 개발사업 중 하나로 스마트 물 관리 장기 연구 사업을 시작하였다. 스마트 물 관리는 수자원 및 상하수도 관리의 효율성 제고를 위하여 스마트 미터, 센서, 디지털지도제작 등 ICT를 이용한 차세대 물 관리시스템이라고 정의할 수 있다. 구체적인 대상 분야를 고려한다면 하천수, 우수, 지하수, 하폐수처리수, 해수담수 등 다양한 수자원의 관리, 물의 생산과 수송, 사용한 물의 처리 및 재이용 등 물 관리 전 분야를 포함한다. 그러나 스마트 물 관리의 용어와 개념을 처음으로 도입한 미국 등 선진국과 관련기업들은 스마트 물 관리를 '스마트 워터 미터, 센서, 첨단 모델링, 수문 지도제작, 스마트 관개농업, 자동화 로봇 등 다양한 기술을 통합적으로 운영하는 지능적인 수자원 관리를 위한 정보네트워크'로 정의한다. 일찍이 도시재생으로의 패러다임 전환을 실시한 영국 및 일본과 달리 한국의 도시재생은 개념, 구성요소, 범위, 사업방식 등의 여러 가지 측면에서 아직 형성단계에 있다. 또한 한국의 스마트 물 관리 논의는 개념정립 측면에서 심층적 논의가 거의 부재하였다. 기존의 논의들은 수자원 혹은 상하수도서비스 분야에서의 연구결과와 기술개발성과를 기계적으로 적용하고 확대하는 측면만을 부각시켰다. 그러나 이와 같은 스마트 물 관리에 대한 논의는 정보통신기술과 물 관리 서비스를 단편적으로 연결하고 적용범위를 제한할 수도 있다는 점에서 한계성이 있다. 본 연구는 국내외 문헌검토를 바탕으로 한국의 도시재생과 스마트 물 관리의 정책을 분석하고 지금까지 별개로 간주된 두 개념의 장점을 융합하여 향후 지속가능한 도시개발 사업으로서의 가능성을 검토하고자 한다.

• Journal of dental hygiene science
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• v.17 no.6
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• pp.463-471
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• 2017

The purpose of this study was to examine the causes of career interruptions among dental hygienists, institutional measures required for their long service and ways of creating a stable employment culture for them in determine how to resolve labor shortage, create stable jobs, and step up the reemployment of idle manpower. In addition, the following suggestions are made for the establishment of a stable employment culture for dental hygienists by analyzing related literature, research materials, and information such as forums for establishing appropriate jobs for female dental workers. First, a system should be set up to prevent career interruption among dental hygienists. The work environment should be improved to prevent career breaks, and the wages, working hours, and working style should be efficiently structured to maintain the tenure of employees. Second, a plan should be devised to make use of idle manpower, and a variety of necessary programs should be developed. With respect to regular working hours, the time conversion system should be used, which reduces the amount of time one would want to work while receiving a national subsidy. Third, dental hygienists working in different occupations for marriage, childbirth, childcare, school and personal hygiene should make a way to return to the dental system immediately when they want. Fourth, the government should take institutional measures and offer down-to-earth support and benefits for women consideration their social characteristics to guarantee a balance between work and childcare.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.67-73
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• 2010

In SIP(Session Initiation Protocol) environment, the presence event notification operation makes presence service user to recognize presence information status changes of the other party. In conventional method, the user should send each SIP SUBSCRIBE message containing the address of the other party to the presence server. Furthermore each presence subscription requires refresh messages, and the amount of notification messages from the other party becomes large. These facts increases network traffic and the load of presence server. In this paper, to solve these problems a new presence list service has been suggested. It uses a presence list consists of URI of the other party and make it possible to subscribe by using one SUBSCRIBE message. So this method decreases the amount of SUBSCRIBE messages and refresh messages, and it also decreases the amount processing event notification messages from the subscribed the other party. And to increase the efficiency, a presence filtering method which enables to include some parts of selected presence information into the notification message body has been also suggested. The implemented system can reduce SIP message related network traffic and message processing time of the presence server. The performance of this proposed system has been evaluated by experiments, and the results showed decreasing of server processing time.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.425-438
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• 1999

In recent days network computing technologies have bee developed rapidly and the extended use of Internet applications for enterprises such as internet/extarnet in and between enterprises has been increased enormously. Therefore the business in the future will be executed by virtual enterprise. Virtual enterprises which is based on information sharing between enterprises are composed of work processes related to information exchange between virtual enterprises, the team members who are representatives of the organizations that are participated in the actual business of virtual enterprises, and members who are representatives of the organizations that are participated in the actual business of virtual enterprises, and environment that are provided by supporting CALS(continuous Acquisition and Life cycle Support or commerce At light Speed). Supporting system of IDE(Integrated Data Environment)for CALS implementation that is provided as an environment of virtual enterprises has to ensure the autonomies of local data and to provide the accessibility of heterogeneous database of enterprises on network transparently for giving user a single global view of data. This paper introduce the design and implementation of the database broker system that can be accessed data transparently by the suers of participated enterprises in the integrated data environment supporting virtual enterprises. The system uses java/CORBA technology in Web environment and Object Query language (OQL) to process the queries of relational database system, object-oriented database system, and file information.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.11 no.4
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• pp.71-78
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• 2016

Religion can affect on every day lives of individuals in society. Also, religion can affect on personal networks and the formation of a social culture that may lead to influence individual decision makers. Religion can influence values and ethics of people in society. However, according to the secularization hypothesis, as an economy becomes more efficient and the members of a society becomes more educated, the influence and control of religion over people tend to become diminished more. How is religion related with entrepreneurship? There are not so many empirical studies that examine relationship between religion and entrepreneurship. The purpose of this article is that we empirically examine how religious commitment, in addition to individual traits such as need for achievement, perceived creativity, problem solving ability and entrepreneurial parents or friends. Our study is based on survey sample of 229 college students in Korea. The results we found are as follows. First, religious commitment does not have effect on entrepreneurial intention. Also, religion commitment has no relationship with need for achievement, perceived creativity, problem solving ability, and entrepreneurial parents or friends. Second, consistent with previous studies, need for achievement and entrepreneurial parents or friends have meaningful effect on entrepreneurial intention. Third, perceived creativity is a full mediation variable between need for achievement and entrepreneurial intention.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.157-168
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• 2009

In this paper, a photovoltaic system is designed with a step up chopper and single phase PWM(Pulse Width Modulation) voltage source inverter. Where proposed Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature because solar cell has typical voltage and current dropping character. The single phase PWM voltage source the inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power. from 10 to 20[%]. The single phase PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In order to enhance the efficiency of photovoltaic cells, photovoltaic positioning system using sensor and microprocessor was design so that the fixed type of photovoltaic cells and photovoltaic positioning system were compared. In result, photovoltaic positioning system can improved 5% than fixed type of photovoltaic cells. In addition, I connected extra power to the system through operating the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and the phase of single-phase inverter of PWM voltage type can be synchronized. And, It controlled in order to provide stable pier to the load and the system through maintaining high lurer factor and low output power of harmonics.