• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.161-167
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• 2022

Ocean waves passing through the underwater bar at a shallow depth experience a shoaling effect caused by decreasing water depth, a nonlinear interaction therein owing to steepening wave slope, and a wave dispersion effect as the water depth increases again. Because this problem includes many complicated phenomena, it is used as a good example of validating a theoretical development or a CFD method for ocean wave applications. Validation is performed mainly for regular waves by comparing the wave elevation patterns in the time domain with the experimental results. In this study, the spectral evolution of wave spectrum is investigated in the frequency domain when a CFD method such as OpenFOAM is applied for this problem. In particular, the effects of initial phase conditions as well as the nonlinear interaction among harmonic waves are studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.390-397
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• 2019

A mechanical model of band sawing saw frame was established according to an analysis of a commonly used saw-frame structure diagram to overcome the problems of low service life, substandard cutting precision and efficiency, and high manufacturing cost caused by the unreasonable design of saw frame. Taking a particular type of sawing machine as an example, stress cycle analysis of the saw blade was carried out according to the mechanical model of the saw frame, and the fatigue analysis model of the most dangerous cross-section point that was most prone to fatigue failure of the saw blade was then established. The fatigue analysis result was used as the basis for the improved design of the saw frame, and the improved detailed saw-frame design parameters were obtained. The results suggested that the saw frame system is much more compact and the saw blade force met the fatigue strength requirements through the improved design. In addition, the service life of the saw blade and the cutting precision were increased. The established mechanical model of the saw frame in this paper is used widely and has high practical application values.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.649-656
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• 2019

Flux cored arc welding (FCAW), which is used widely in many fields, such as shipyards, bridge structures, construction machinery, and plant industry, is an alternative to shielded metal arc welding (SMAW). FCAW is used largely in the welding of carbon and alloy steel because it can be welded in all poses and obtain excellent quality in the field under a range of working conditions. In this study, the mechanical properties of welded parts were analyzed after different welding of SS400 and SM490A using FCAW. The following conclusions were drawn. The tensile test results satisfied the KS standard tensile strength in the range of 400~510 N/mm2 in all welding positions. The bending test confirmed that most of the specimens did not show surface breakage or other defects during bending and exhibited sufficient toughness, even after plastic deformation. The hardness test results were lower than the standard value of 350 Hv of KS B 0893. Similar to the hardness test, were greater than the KS reference value. The macro test revealed no internal flaws, non-metallic inclusions, bubbles or impurities on the entire cross section of the weld, and there were no concerns regarding lamination.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.279-285
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• 2019

Transverse vibrations of a ship's aft end and deckhouse are mainly induced by transverse exciting forces from the main engine. Resonance should be avoided in the initial design stages when there is a prediction of resonance between the main engine and transverse modes of the deckhouse. Estimates of frequencies for resonance avoidance are possible from the specifications of the main engine and propeller, but the inherent vibration frequency of the structure around the engine room is not easy to estimate due to the variation in the shape. Experience-oriented vibration design is also carried out, which results in many problems, such as process delay, over-injection of on-site personnel, and iterative performance of the design. For the flexible design of 8,600 TEU container vessels, this study addressed the resonance problem caused by the transverse vibration of the main engine when only the main engine was changed from 12 cylinders to 10 cylinders without modification of the hull structure layout. Efficient structural reinforcement design guidelines are presented for avoiding resonances with the main engine lateral vibration and the structure around the engine room. The guidelines are expected to be used as practical design guidelines at design sites.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.237-245
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• 2018

This study was conducted to identify the effects of baby care using dolls on nursing students' contraceptive attitude, sexual attitude, and recognition of unmarried mothers. A quasi-experimental nonequivalent control group, pretest-posttest design was used. The subjects of the study were 104 nursing college students who agreed to participate. The control group (n=52) received lecture sex education while the experimental group (n=52) received lecture sex education and baby care education using a doll. The contraceptive attitude, sexual attitude, and unmarried mother's recognition were then examined. Data were collected from September to December, 2017 and analyzed using descriptive statistics, ${\chi}^2$-tests, and t-tests with the SPSS/WIN 21.0 program. The scores of contraceptive attitude differed significantly between the experimental group and the control group (t=4.66, p=<0.001). Additionally, the sexual attitude score of the experimental group was lower than that of the control group (t=-2.23, p=0.028), with pleasure playfulness showing a significant decrease (F=3.96, p=<0.001). However, recognition of unmarried mothers did not differ significantly between groups (t=-0.08, p=0.937). Overall, the results showed that baby care using a doll has positive effects on contraceptive attitude and sexual attitude. In the future, effective sex education should include methods that complement lectures.

• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.585-599
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• 2022

This study examines the types and characteristics of the policy instruments of Korea's higher education policies since the Lee Myung-bak administration. To this end, McDonnell and Elmore (1987)'s types of policy instruments were adopted and the higher education policy tasks announced by the Ministry of Education were classified by sector and type. As a result of the analysis, Korea's higher education policy showed a tendency to gradually shift from 'mandates' to 'inducements' and 'capacity building'. Despite this trend, however, in policy tasks such as university evaluation, the Lee Myung-bak, Park Geun-hye, and Moon Jae-in administrations all maintained policy instruments that combine 'mandates' and 'inducements'. Third, the 'system change' based on a market-oriented mechanism was used only in the Lee Myung-bak administration, and was not adopted in the higher education policies of the Park Geun-hye and Moon Jae-in administrations. In the field of global and industry-university cooperation at universities, it is encouraging that the Lee Myung-bak administration to the Moon Jae-in administration have steadily introduced policy instrument of 'capacity building', but in the fields of specialization and competitiveness enhancement, policies centered on 'mandates' and 'inducements' was using the policy instrument.

• Journal of Navigation and Port Research
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• v.47 no.3
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• pp.147-154
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• 2023

This study aims to determine the necessity, role, utilization, and operation and management plan in relation to the underwater space platform where humans can newly reside. It provides a comprehensive opinion on the need for creating undersea space and operation plans based on opinions of industry-university-affiliated organizations involved in the R&D project of the Ministry of Maritime Affairs and Fisheries for the utilization of undersea space and external experts participating in marine technology development. In this study, a survey was conducted on researchers participating in the construction of a Korean submarine space platform. FGI was conducted on marine technology development experts. Results were then derived. As a result of the analysis, the need for subsea space construction was found to be high. As for the role of subsea space, the most common opinion was to develop technology for utilizing subsea space and to secure marine science research functions. It was found that the creation of subsea space would have a positive impact on the domestic industry, especially the deep-sea development industry and the shipbuilding/offshore structure industry. In terms of utilization, after the end of the seabed space test bed, the response to utilization as a marine observation base and marine ecosystem research had the highest proportion. As for expected inconvenience, discomfort in the psychological environment was the highest. Experts suggest that securing a continuous budget is most important for stable operation in the future and that securing a manpower budget is essential for itemized budgets. In addition, it was judged that it would be appropriate to establish a prior agreement from the time of the prior agreement and prepare a countermeasure before proceeding with the project in order to ensure ownership issues, consignment management issues, and cost issues when using the project after the end of the project.

• 선박안전기술공단연구보고서
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• s.4
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• pp.1-108
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• 2007

2007. 7. 23 IMO의 NAV(항해안전전문위원회)53차 회의에서는 e-Navigation을 해상에서의 안전, 보안, 해양환경보호를 목적으로 전자적인 수단에 의해 선박과 육상에서 해양정보를 수집, 교환, 표시함으로써 항구와 항구간의 항해 및 관련된 서비스를 향상시키는 것으로 정의하고 있다.2005년 11월 영국의 교통부 장관 Stephen 박사는 Royal Institute ofNavigation에서의 연설에서 해상안전과 환경보호를 위하여 선박의 항해를 감시하는 관제소 및 항행하는 선박에 유용하고 정확한 정보가 더 많이 필요함을 역설하였다. 그리고 첨단 기술에 의해 자동화된 항공 항법분야를 예로들면서, 선박의 항법 분야도 항해와 관련된 모든 시설 및 작업을 전자적 수단으로 대체하는 개념인 e-Navigation으로 전환되어야 하며 영국은 이에 필요한 작업을 주도하겠다는 의견을 피력하였다. Stephen은 e-Navigation 도입으로 얻을 수 있는 이익으로 첫째, 항해 실수로 인한 사고 확률저감, 둘째,사고 발생 시 인명 구조 및 피해 확산을 위한 효율적 대응, 셋째, 전통적인항해시설 설치 불필요로 인한 비용 저감, 넷째 선박입출항 수속의 간편화 및항로의 효율적 운용으로 인한 상업적 이익 등을 들었다. 반면에e-Navigation 체계로 전환 시 예상되는 장애로는 첫째, 체계 구축을 위한 비용(특히 개발도상국가들의 경우 어려움 예상), 둘째, e-Navigation의 성과 달성을 위하여 세계 전 해역의 모든 선박이 e-Navigation 체계에 동참하도록유도하는 문제, 셋째, 전자해도 표시 및 선교 장비들에 대한 표준화 문제, 넷째, 육상에 설치할 e-Navigation 센터의 설계 및 구축 등을 꼽았다.IMO는 2005년 81차 MSC(해사안전위원회) 회의에서 영국이 일본, 마샬아일랜드, 네덜란드, 노르웨이, 싱가포르, 미국과 공동으로 제안한 ‘e-Navigation전략 개발’ 의제를 2006년 82차 MSC 회의에서 채택하고, NAV(항해 전문위원회)를 통하여 2008년까지 e-Navigation의 구체적 개념을 정립하고 향후 개발하여야 할 전략적 비전과 정책을 수립하기로 하였다. 이어서 영국을 의장으로 e-Navigation 전략개발 통신작업반이 구성되었는데, 지난 년간 19개국, 16개 전문기관이 참여하여 아래의 작업이 수행되었다. ○ e-Navigation 개념의 정의와 목적 ○ e-Navigation에 대한 핵심 이슈 및 우선 순위 식별 ○ e-Navigation 개발에 따른 이점과 단점의 식별 ○ IMO 및 회원국 등의 역할 식별 ○ 이행계획을 포함한 추가 개발을 위한 작업계획의 작성 IMO에서 수행되고 있는 e-Navigation 전략 개발 의제 일정은 2008년까지이다. 이 전략 개발에 있어서 중요한 요소는 e-Navigation이 포함할 서비스범위, 포함하는 서비스 제공에 필요한 인프라 및 장비의 식별, 인프라 구축및 운용비용을 부담할 주체에 대한 논의, e-Navigation으로 인한 이익과 투자비용에 대한 비교 분석 등이다. 이 과정에서 정부, 선주, 항만운영자, 선원등의 입장 차이와 선진국과 개발도상국 간의 경제 수준 차이는 전략 개발에있어 큰 어려움을 줄 것이므로, 이들이 합의된 전략을 만들기 위해서는 예정된 기간보다 다소 늦어질 가능성도 있다.e-Navigation 전략 개발이 완료되면 1단계로는 해상교통 관제시스템, 선박선교 장비, 무선 통신장비 등에 대한 표준화 작업이 이루어질 것이다. 이 과정에서 각국 간에 자국 보유 기술을 표준화시키기 위한 경쟁이 치열할 것으로 예상된다. 2단계에서는 e-Navigation 체계 하에서의 다양하고 풍부한 서비스 제공을 위한 관련 소프트웨어 및 하드웨어의 개발이 이루어질 것으로전망되는데, 이는 지난 10년간 육상에서 인터넷망 설치 후 이루어진 관련 서비스 산업의 발전을 돌아보면 쉽게 짐작할 수 있을 것이다.e-Navigation 체계 하에서 선박의 항해는 현재와는 전혀 다른 패러다임으로 바뀔 것이다. 예를 들어 현재 입출항 시 요구되던 복잡한 절차는one-stop 쇼핑 형태로 단순화되고, 현재 선박 중심의 항해에서 육상e-Navigation 센터가 적극적으로 관여하는 항해 체계로 바뀔 것이며, 해상정보의 공유와 활용이 무선 인터넷을 통해 보다 광범위하게 이루어질 것이 다.e-Navigation의 잠재적 시장 규모는 선박에 새로이 탑재될 지능형 통합 항법시스템 구축과 육상 모니터링 및 지원 시스템 등 직접 시장이 약 50조원,전자해도, 통신장비, 관련 서비스 컨텐츠 등 간접 시장의 규모가 150조원으로 총 200조원으로 대략 추산하고 있다. 향후 이 거대한 시장을 차지하기 위한 전략 수립이 필요한 시점이다. 지금까지 항해 장비 관련 산업은 선진국의일부 업체들에 의해 독점되어 왔다. 우리나라는 조선과 해운에서 모두 선진국임에도 불구하고 이 분야에서는 대부분 수입에 의존해 왔다. e-Navigation체계 하에서는 전체 시장이 커지고 장비의 사양이 표준화됨에 따라 어느 소수 업체가 현재처럼 독점하기는 더 이상 어려울 것으로 예상된다. 따라서e-Navigation은 우리나라도 항해 장비 분야 시장을 차지할 수 있는 좋은 기회라고 할 수 있다. 특히 조선 1위의 장점을 적극 활용한다면 다른 나라보다우위의 경쟁력을 확보할 수도 있다. 또한, 서비스 분야의 시장은 IT 기술과밀접한 관계가 있으므로 IT 강국인 우리나라가 충분한 경쟁력을 갖고 있다고 할 수 있다.그러나, EU를 비롯한 선진국에서는 이미 e-Navigation 에 대비한 연구를10여년 전부터 수행해 왔다. 앞에서 언급한 EU의 MarNIS 사업은 현재 거의마무리 단계로 당장 실용화 할 수 있는 수준에 있는 것으로 보인다. 늦었지만 우리도 이를 따라잡기 위한 연구를 서둘러야 할 것이다. 국내에서도e-Navigation의 중요성을 깊이 인식하고, 2006년에는 관련 산학연 전문가들로 작업반을 구성하여 워크숍 등을 개최한 바 있다. 또한 해양수산부에서도e-Navigation 핵심기술 개발을 위한 연구사업을 기획 추진하고 있다.그러나 현재 항해통신장비들의 기술기준은 ITU의 전파규칙(RR)과 IMO결의 및 SOLAS 협약을 따르고 있는데 이들 규약이나 결의에 대한 국제적인 추이와 비교할 때 국내의 기술은 표준화되지 못한 부분이 많은 실정이다.본 연구에서는 e-Navigation sytem중 표준화가 필요한 요소와 전자해도,AIS 등 e-Navigation(통합전자항법시스템)관련 국내산업현황 실태조사를 통해 국내 e-Navigation기술개발 동향에 대해 조사하고자 한다.

• Korea Science and Art Forum
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• v.19
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• pp.243-257
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• 2015

The Cultural Heritage Administration has selected Seoul Fortress Wall as the representative heritage of Korea to be applied for being registered as UNESCO World Heritage and announced the plan to restore and organize it, which has increased the interest to the Seoul Fortress Wall, the Historical Site No. 10. The great work to make the heritage value of Walls, 4 Big Gates and 4 Small Gates composing the Seoul Fortress wall with the length of 18.627 km to be recognized worldwide has limits if it is focused only on the physical restoration. It is because the Seoul Fortress Wall represents the long historical and cultural value as the space of life which connects closely the capital city and its vicinity. We need the plan to discover and utilize historical and cultural contents of Seoul Fortress Wall and its vicinity. Especially, Gwangheemun, which is one of the four Small Gates of Seoul Fortress Wall, is a precious cultural heritage which represents the transition of fortification technology of Chosun period as the space representing ordinary people. However, now Gwangheemun and its vicinity does not stand out the charm because of passive accessibility, landscape falling behind and absence of program. This made the lack of domestic and overseas tourists and the convenient space and various contents. This reality is because the value of space has been considered simply as a cultural heritage without considering the traditional, historical and cultural specificity. Therefore, this study is aimed to find the meaning and value of Gwangheemun by discovering its own latent intangible cultural, historical and artistic resource, and to find the way to connect with Gwangheemun, the existing tangible traditional architectural space and the way of vitalizing Gwangheemun as a new space.