• Journal of Navigation and Port Research
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• v.46 no.6
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• pp.525-529
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• 2022

In the eLoran system, the Loran Data Channel (LDC) is used to provide precise timing and positioning. The LDC message can be modulated with the Eurofix method, which modulates the transmission time of the 3rd-8th pulse not used for navigation, and the 9th pulse method, which modulates data using the 9th additional pulse after the existing 8 Loran pulses. In this paper, we analyzed the reception performance of the LDC message transmitted from the eLoran transmitter according to the modulation method. The eLoran testbed transmitter in Incheon was set to transmit LDC messages simultaneously with the 9th pulse modulation method and the Eurofix modulation method. Then, the LDC messages stored in the databases of the eLoran differential stations in Incheon and Pyeongtaek were analyzed in terms of the message reception rate according to the modulation method. Using the navigation aid management ship Inseong No. 1, the range of LDC message reception of actual sea users near Incheon Port was also analyzed. The results of this study are expected to be utilized in the full operational capability service after the eLoran pilot service.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.969-977
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• 2022

In order to respond to the increase in water disasters due to climate change and urbanization, research on low impact development (LID) techniques and application to cities are expanding. The LID technique is a technology that reduces rainwater runoff in the city, controls various water disasters such as flash floods, etc. in an eco-friendly way, and restores the urban water circulation system to a natural water circulation system. However, quantitative analysis of stormwater runoff reduction through the LID technique is insufficient. Therefore, this study analyzed the ratio of the permeable area required to reduce the surface runoff of rainfall (25 mm/hr, 50 mm/hr, 100 mm/hr) with respect to the impervious watershed area of the old city using the permeable pavement. As a result of the analysis, it was found that a permeable area ratio of 7.14 to 12.63% of the total area was required for 25 mm/hr, 15.79 to 26.97% for 50 mm/hr, and 30 to 55.81% for 100 mm/hr.

• Journal of Korean Elementary Science Education
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• v.24 no.4
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• pp.391-398
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• 2005

Recent studies say that informal learning is influential to students as much as formal teaming. Nowadays we can see various informal teaming inside and outside of the country. In 2004, it was the first attempt in Korea that engineer had gone to the elementary school fur activity that included scientific experiment and engineering work with students. National Academy of Engineering of Korea (NAEK) progressed activity with companies and elementary schools for students' making sense of engineer and what they are doing. To do that, NAEK had developed the network that company could support its local school's science education circumstance by engineers' visiting program. In 2004, seventeen companies including both large and small ones took part in the program called' Korea Junior Engineering Achievement (KJEA)'. In this program, engineers played the role of teacher (we call them company teacher), elementary school teachers played the role of organizing classes as a mediator. Elementary school teachers and company teachers' recognition is very important to make students' activity meaningful. The aim of this study was to give implication for informal science education activity for which engineers visit their local school. We got the result by survey and interview of company teachers and elementary school teachers. This study's result shows that almost company teachers and school teachers were in favor of purpose of this informal science education activity and satisfied with their participation. But some company teachers were not satisfied with worksheets, materials provided and relationship between school and company). Elementary school teachers and company teachers, both of them believed students' program as the key factor of success of informal science education activity. To make informal science education grow, school administrator and teacher need to have a will to utilize the activities more actively.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.6
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• pp.173-189
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• 2023

As supreme technologies continue to be developed, industries such as artificial intelligence, biotechnology, robots, aerospace, electric vehicles, and solar energy are created, and the macro business environment is rapidly changing. Due to these large-scale changes and increased complexity, it is necessary to pay attention to the effect of social capital, which can create new value by utilizing capital increasing the importance of relationships rather than technology or asset ownership itself at the level of start-up strategy. Social capital is a concept first proposed by Hanifan in 1916, and refers to the overall sum of capabilities or resources that are latent or available for use in mutual, continuous, organic relationships or accumulated human relationship networks between individuals or social members. In addition, the diversity of start-up teams with diverse backgrounds, characteristics, and capabilities, rather than one exceptional founder, has been emphasized. Founding team diversity refers to the diversity of in-depth factors such as demographic factors, beliefs, and values of the founding team. In addition, changes in the macro environment are emphasizing the importance of technology start-ups and laboratory start-ups that lead industrial innovation and create the nation's core growth engines. This study focused on the I-Corps' program. I-Corps, which means innovation corps, is a laboratory startup program launched by the National Research Foundation (NSF) in 2011 to encourage entrepreneurship and commercialization of research results. It focuses on forming a startup team involving professors, researchers and market discovery activities. Taking these characteristics into account, this study empirically verified the impact of social capital from a network perspective and founding team diversity on I-Corps start-up performance. As a result of the analysis, the educational diversity of the founding team had a negative (-) effect on the financial performance of the founding team. On the other side, the gender diversity and the cognitive dimension of social capital had a positive (+) effect on the financial performance of the founding team. This study is expected to provide more useful theoretical and practical implications regarding the diversity, social capital, and performance interpretation of the I-Corps Lab startup team.

• Journal of The Korean Association For Science Education
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• v.39 no.6
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• pp.777-790
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• 2019

The purpose of this study is to investigate the experience of teachers who apply Smart-technology in elementary school STEAM class and the reasons, difficulties when applying the technology and required support. Semi-structured in-depth interviews were conducted with six elementary school teachers with specialized knowledge in STEAM education who have experienced STEAM lessons several times before. The research findings are as follows: First, research participants utilized a variety of Smart-technology in STEAM class, most of which were experiential or interactive technology. Among the STEAM learning criteria, the Smart-technology in 'Creative Design' course was most often applied. Second, they adopted Smart Technology in STEAM class to encourage students to feel interested, actively participate in the class, enjoy indirect experience, and nurture interest in state-of-the-art technology. They used it to prepare for future societies and organize classes that are suitable for STEAM learning criteria. They also used Smart-technology because it was easy to use. Third, they found it difficult to find, secure, and use suitable Smart-technology when applying Smart-technology in the STEAM class. They also had trouble restructuring the curriculum. In addition, there were difficulties in using Smart-technology in the class such as lack of class hours, increased level of activity, insufficient physical environment and unexpected malfunction of Smart-technology, thus interrupted the class. After the class, it was hard to manage Smart-technology and also, there were difficulties in assessment, record, and negative awareness of surrounding people. Fourth, they mentioned that's suggesting education guidelines, develop, and distribute educational materials are required to enable 'Creative Design,' reduce educational content, provide training, secure Smart-technology equipment and provide Wi-Fi, support teacher's club and communities and create an atmosphere to emotionally support teachers in order to activate using Smart-technology in STEAM class.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.37-46
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• 2014

Industrialization and urbanization have led automobiles to transform into more than just modes of transportation; they have become daily necessities as well as extensions of living spaces where a variety of activities can be done and automotive applications of the latest information technology are accelerated. Though material abundance has increased in the modern society, the conflicts and the stress emerging from a social structure focused on competition have increased as well. Such lifestyles generate a need for personal space and media content for healing the body and the mind. This research explores the automotive application of video content with the goal of refreshing the minds of the passengers. To this end, previous studies have investigated the emotional effect of videos, focusing on the responses of diverse groups of adults (age group of 20 to 60) who frequently used automobiles, which had video displays installed in them. The results showed that watching video contents on a full window inside a car influenced the creation of positive feelings7 and emotional satisfaction. The research attempts to study the methods of providing video contents and the effects of watching them that could aid the emotional well-being of passengers, and presents the possibility of emotional satisfaction created by a convergence of cars and multimedia contents in the future.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.4
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• pp.9-20
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• 2011

Future warfare paradigm is changing to network-centric warfare and effects-based operations. In order to find first and strike the enemy in the battlefield, friendly unit requires real-time target acquisition, intelligence collection, accurate situation assessment, and timely decision. The rapid development in advanced sensor technology and wireless networks requires a significant change in operational concepts of the battlefield surveillance. In particular, the introduction of a battlefield surveillance sensor network system is a big challenge to the ground forces which have lack of automated information collection assets. Therefore this paper proposes an ontology-based context-aware framework for the battlefield surveillance sensor network system which is needed for early finding the enemy and visualizing the battlefield in the ground force operations. Compared with the performance of existing systems, the one of the proposed framework has shown highly positive results by applying the context systems evaluation method. The framework has also proven to be satisfactory by the structured evaluation method using device collaboration. Since the proposed ontology-based context-aware framework has a lot of advantages in terms of scalability and reusability, the ground force's reconnaissance and surveillance system can be widely applied to expand in the future. And, ontology-based model has some weak points such as ontology data size, processing time, and limitation of network bandwidth. However, these problems can be resolved by customizing properly to fit the mission and characteristics of the unit. Moreover, development of the next-generation communication infrastructure can expedite the intelligent surveillance and reconnaissance service and may be expected to contribute greatly to expanding the information capacity.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.10-10
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• 2000

램제트 엔진은 비추력이 높고 추력 레벨은 낮으므로, 2단 추진기관에 적합한 추진 시스템이다. 1단-추진기관의 작동이 끝나고, 2단 램제트 엔진이 점화 후 안정된 연소에 도달되기까지 비행체의 속도는 항력에 의하여, 초당 약 마하수 0.1 정도씩 감소된다. 1단 연소 후 2단 램제트로 전환되는 지연시간이 길수록 1단에서 요구되는 종말 가속도는 증가되므로, 1단이 차지하게되는 부피는 증가되고 비행체의 크기 또한 늘어나게 된다. 따라서 1단에서 2단 램제트로 천이되는데 소요되는 시간을 가능한 짧게 하는 것이 효과적이다. 그러나 램제트 엔진의 특성상 선결되어야할 다음과 같은 여러 문제들이 있다. 첫째, 1단 작동 시 공기 흡입구와 연소실은 차단벽으로 분리되어 있다가, 1단 연소후 차단막이 제거되어 외부공기가 램제트 연소실로 흡입된다. 흡입되는 공기는 흡입구의 형상에 의하여 램 압축되지만 초음속으로 연소실을 통과하게된다. 연료 주입 구에서 공급되는 연료는 연소실에서 유동의 흐름방향(streamline)에 따라서 연소실로 확산되는데, 연소되기 전에는 유속이 빠르게 노즐로 빠져 나가므로 램제트 연료가 재순환 구역(recirculation zone)으로 침투하는데 쉽지가 않다. 둘째, 연소실 입구에서 발생되는 와류 (ring vortex)는 1단 연료의 고온 연소 가스를 연소실로 확산시키는데, 비 균일한 온도 분포를 유발하여 램제트 연료의 점화에너지가 공급되는 시간이 적당하지 않을 경우 균일한 화염 전파에 악영향을 준다. 셋째, 연소실에서의 빠른 유동 조건은 연료가 연소실에 머무를 수 있는 시간을 감소시키며, 연소실 입구에서 강한 전단 응력이 발생되어 화염이 안정화되는데 악 영향을 미치게된다. 본 논문은 공기 흡입구, 연소실 및 노즐을 통합하여 수치해석을 하였으며 열유동/점화/연소등의 미케니즘을 이해하고, 주요 인자들 중 와류의 영향에 초점을 맞추었다.다고 판단되며 배기 가스 자체에 대기 공기중에 함유되어 있던 습기가 얼어붙는(Icing화) 문제가 발생하기 때문에 배기가스의 Icing을 방지하기 위하여 압축기 끝단에서 공기를 추출하여 배기부분에 송출할 필요성이 있는 것으로 판단되었다. 출구가스의 기체 유동속도가 매우 빠르므로 (100-l10m.sec) 이를 완화하기 위한 디퓨저의 설계가 요구된다고 판단된다. 또 연소기 후방에 물을 주입하는 경우 열교환기 및 기타 부분품에 발생할 수 있는 부식 및 열교환 효율 저하도 간과할 수 없는 문제로 파악되었다. 이러한 기술적 문제가 적절히 해결되는 경우 비활성 가스 제너레이터는 민수용으로는 대형 빌딩, 산림, 유조선 등의 화재에 매우 적절히 사용되어 질 수 있을 뿐 아니라 군사적으로도 군사작전 중 및 공군 기지의 화재 그리고 지하벙커에 설치되어 있는 고급 첨단 군사 장비 등의 화재 뿐 아니라 대간첩작전 등에 효과적으로 활용될 수 있을 것으로 판단된다.가 작으며, 본 연소관에 충전된 RDX/AP계 추진제의 경우 추진제의 습기투과에 의한 추진제 물성 변화는 미미한 것으로 나타났다.의 향상으로, 음성개선에 효과적이라고 사료되었으며, 이 방법이 편측 성대마비 환자의 효과적인 음성개선의 치료방법의 하나로 응용될 수 있으리라 생각된다..7%), 혈액투석, 식도부분절제술 및 위루술·위회장문합술을 시행한 경우가 각 1례(2.9%)씩이었다. 13) 심각한 합병증은 9례(26.5%)에서 보였는데 그중 식도협착증이 6례(17.6%), 급성신부전증 1례(2.9%), 종격동기흉과 폐염이 병발한 경우와 폐염이 각 1례(2.9%)였다. 14) 식도경 시행회수는 1회가 17례(54.8%), 2회가 9례(29.0%), 3회 이상이 5례(16.1%)였다.EX>$IC_{50}$/ 값이 210 $\mu\textrm{g}$/$m\ell$로서 효과적

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1969-1980
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• 2013

The Traffic congestion is caused by the increasing traffic demand. Thus, economic losses have been increasing every year. To solve these problems, car sharing and rental car systems that are equipped with IT technologies emerge. Car sharing has many advantages-the alleviation of the traffic congestion, the saving of maintenance cost for cars, the reduction of car possessiveness, the solution for the hassle of car ownership, for business and personal duty, and the improvement of connectivity between public transportations-. The goal of the car sharing is to achieve low-carbon and eco-friendly transportation. In this study, we review papers related to the car sharing system and the cost system of traffic systems. We estimate the optimal cost of the cloud traffic system that is one of the car sharing services. We suggest a methodology to estimate operational cost and use cost through the analysis of cost system between similar traffic means. The range of the maximum and minimum cost was determined through the comparison and analysis of similar traffic means. Expected demand and the cost that people are willing to pay were estimated through optimized value pricing. The minimum cost per hour that was compared to the cost of rental car was estimated at 5,333 won and the maximum cost per hour that was compared to taxi cost was estimated at 17,700 won. The cost for users was estimated at 6,930 won. The cost of 50% demands was estimated at 6,550won. Future studies should analyze service hours of users, weather, demand pattern and trend and consider them into the cost estimation.

• Progress in Medical Physics
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• v.20 no.4
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• pp.253-259
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• 2009

We have developed standards based on international criterions for the quality control of dose tested by the measurement institutions of individual exposure doses through improving the reliability of data on the exposure dose of individuals working in radioactive environment and securing the accuracy and reliability of individual dose measurements. Laws related to radiation dose applied to domestic institutions refer to ANSI N13.11.1993, but currently, in U.S. and some other countries the measurement of radiation doses is based on ANSI N13.11.2001 that reduced test categories and tightened the standards. We made efforts to simplify the standards and to reduce the number of dosimeters required in experiment, and avoided preventing or hindering the use of future technologies not approved under the current law such as glass dosimeter and optical stimulation dosimeter. The Quality Management Manual of Radiation Dosimetry Service, Assessment Manual of Radiation Dosimetry Service Accreditation Program, and the Personnel Dosimetry Performance. Criteria for Testing are documents applicable in supervising laboratories.