• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.606-614
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• 2020

In this paper, we analyze the influences of ship traffic and marine weather information on underwater ambient noise. Ambient noise is an important environmental factor that greatly affects the detection performance of underwater sonar systems. In order to implement an automated system such as prediction of detection performance using artificial intelligence technology, which has been recently studied, it is necessary to obtain and analyze major data related to these. The main sources of ambient noise have various causes. In the case of sonar systems operating in offshore seas, the detection performance is greatly affected by the noise caused by ship traffic and marine weather. Therefore, in this paper, the impact of each data was analyzed using the measurement results of ambient noise obtained in coastal area of the East Sea of Korea, and public data of nearby ship traffic and ocean weather information. As a result, it was observed that the underwater ambient noise was highly correlated with the change of the ship's traffic volume, and that marine environment factors such as wind speed, wave height, and rainfall had an effect on a specific frequency band.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.154-164
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• 2013

In this study, a new type floating breakwater was proposed to improve the capability of wave attenuation compared with the existing floating breakwater in Wonjun Port, which is located in Masan City, Korea. In order to develop the optimal design, many different configurations considering the shape and location of vertical barrier and horizontal plate were examined based on the shape of existing floating breakwaters in Wonjun and Tongyeong Port. The analytical and numerical results of the new type floating breakwater showed better performance in long-period wave attenuation than the existing floating breakwater in Wonjun. Therefore, the new type floating breakwater can improve harbor tranquility in Wonjun Port.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.177-188
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• 1991

The littoral drift in the nearshore zone occurs mainly due to wave action and nearshore currents. Beach topotraphical evolution model presented in this study shows the possibility which can be applied to the prediction of beach deformation over short time interval, associated with the construction of coastal structures. The 3-dimensional beach evolution model, based on Watanabe's equation and Deguchi's flux model, is developed and consists of three submodels of wave transformation, rip-currents, and beach deformation. This model is applied to the several cases with different conditions and compared with the results of Watanabe's numerical model. In addition, the effects of parameters involved are discussed.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.122-133
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• 2005

The change of surface sediment composition, shoreline and transection of geography were studied to investigate the Typhoon(Maemi) effect in Naa Beach located in the south area of East sea. In the backshore the volume of gravel is do creased, and increased in the volume of sand. The erosion in the sediment occurred to 4 m in the thickness and effected to 10 m in depth. And the coastline retreated to 12 m after typhoon. During typhoon conditions, higher amplitude waves deepen the wave base, causing much of the lower beach face and the offshore. The upper beach face is extensively eroded during typhoon and sand sediment is redeposited.

• Journal of the Korean Wood Science and Technology
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• v.39 no.6
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• pp.521-530
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• 2011

Nowadays, market demand of structural Glulam is growing and diversifying. The durability of Glulam should be significantly considered when they are intended to apply for out-door use such as timber bridge and pergola. This study was aimed to develop the manufacturing process of preservative treated structural Glulam using domestic softwood species. 10 m long structural Glulam were manufactured from domestic pitch pine logs with CuAz-3 preservative treatment. At each manufacturing process, the production yield was evaluated. Finally, bending tests were performed to verify the structural performance of manufactured Glulam. From the results, it was shown that the preservative treatment process hardly influenced on the production yield. But domestic pitch pine was proved to not be suitable for making the preservative treated Glulam due to the large difference of preservative permeability between sapwood and heartwood.

• JOURNAL OF ELECTRICAL WORLD
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• s.351
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• pp.89-94
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• 2006

에너지 해외의존도 97%, 무역의존도 70%인대한민국. 우리는하루220만배럴, 연간8억배럴이상을소비한다. 부존자원이 극도로 빈약한 우리나라가 나아가야 할 길은자명하다. 에너지 자원을 거의수입해 의존하다보니 이를고부가화 해 내수에 돌리면서 최우선으로 수출을 통해 온나라가 먹고 살고 있다해도 과언이아니다. 해외 에너지자원을 안정적으로 확보하는 것이 바로 국가경쟁력의 근원이 되는것은 어제오늘의 일이 아니다. 고유가 파고를 헤쳐나가야 한다는 절박한현실에서안정적인 에너지자원확보를 위한 정부의 해외자원분야 정책 및 민관전략이 올들어 의욕적으로 전개되고 있다. 우선정부는 자원개발 업무를 강화하기 위해 현재1과1팀의 자원개발조직을 보강하 고유전개발팀을 신설하는 등 모두3개팀으로 늘린다. 나아가 해외 자원확보에주력 산업 동반진출도 착착진행하고 있다. 국내 자원 개발 기업과 에너지관련기업, 해외진출기관등 14곳으로 구성된 ‘에너지산업해외진출협의회’도 최근 출범시켰다. 유전을탐사하거나 개발하는데 개인들도간접투자할수있는 ‘유전개발펀드’도 7월에 첫 선을 보인다. 약2000억원규모의이 시범펀드 도입 등을 통해 자원개발을 가속화,2013년까지원유-가스자주개발률을18%(원유15%, 가스30%)까지 끌어 올릴 계획이며 여기에16조원 신규투자가 소요 될 것으로보고있다. 이같은 일련의 공격적인 움직임은 단순히 돈을 주고 자원을 사오는 기존방식을 앞으로는과감히탈피,자원부국이 원하는 산업인프라등을 수주해제 공한뒤 그 대가로자원을 확보하는 총체적 자원확보전략에 무게를두겠다는 의지를 담고 있어 고무적이다. 여기에 다원유 등 수입원자재 가격이 급등세를 보이고있는 가운데 우리나라의 해외 자원개발사업이 활기를 띠고있다.석유공사는 민간기업들과 함께 지난해에만 예멘2곳 등 전세계 5개국9곳의 석유 및 천연가스 광구계약을체결, 올들어 최근참여사들과 함께 주주간계약 서명식을 갖고본격적인 사업을 추진 중이다. 광업진흥공사역시 SK네트웍스와제휴, 최근 전체 매장량이650만t으로 추정되는 중국 후난성의 아연광 탐사권을 획득, 합작 사설립계약을 체결한 것으로 알려지고 있다. 민간기업들도 해외자원분야진출이 활발하다. 기업들의 해외 자원개발을 위한 투자규모도 늘어 올해38개 해외 자원개발기업이 32개국 211개 사업에 모두31억달러를 투자할 계획인것으로 나타났다. 이에본지는 올해 들어서도 고유가의 지속으로 속증하고 있는에너지수입동향과 해외 자원 개발의 현실과 문제점, 개선방향, 나아가 최근 안전적인 자원확보를 위한 동향을 진단해본다.

• Journal of Korean Association for Spatial Structures
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• v.7 no.1 s.23
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• pp.79-85
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• 2007

Steel plate bonding method with epoxy is common applied to repair and strengthen RC structures, but Steel is apt to corrode quickly, hard to manufacture and heavy. To overcome these defects, it is carried out research on strengthening RC structures with FRP(Fibre Reinforced Polyrner/Plastic) FRP is generally used in the shape of Plate or Sheet, but it has weak point such as premature failure, difficult work. To cope with these problem, NSMR(Near Surface Mounted Reinforcement) which uses CFRP in the shape of Rod is proposed and carried out active research on strengthening effect of variables such as quantity, anchorage length and space of CFRP-Rod. Strengthening with CFRP-Rod is carried out under loading to some degree in fact, and so the amount of pre-loading is selected as variable in this research. The amount of pre-loading is chosen in proportion to nominal strength of non-strengthened specimen with CFRP-Rod.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.2
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• pp.201-208
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• 2013

In this paper, the PTS scheme generate alternative orthogonal frequency frequency division multiplexing (OFDM) signal sequences by multiplying all the time domain samples with phase rotating vectors to find an OFDM signal having the minimum peak-to-average power ratio (PAPR). However, it needs an exhaustive search which causes large computational complexity. In order to solve this problem, we propose two efficient methods based on the crest factor. The first proposed scheme is to select time domain sample with large magnitude to calculate PAPR, and the next scheme is to calculate the absolute value of real and imaginary part of the sample at each subblock. The simulation results show that the proposed schemes achieve better PAPR reduction performance than existing PTS schemes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1033-1039
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• 2012

Artificial joints are used when joints lose their function because of either the destruction or damage of the composing bones of the joints. To evaluate the primary stability of a femur-implant system, the relative displacement caused by a repeated load is measured immediately after the insertion of the artificial joint. For more accurate stability evaluation, the accurate measurement of the penetration displacement of the artificial joint to the bone and the rotation angle of the artificial joint is essential. In this study, to evaluate the primary stability of the femur-implant system, we propose a new relative displacement measurement method. By using this new method, we comparatively evaluate the primary stability for various surgical methods and the varying stiffness of the cadaver femur-implant itself.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.91-105
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• 2013

This study performed an assessment of wave power potential in the Kangwon and Dongnam regions encompassing the East Sea and part of South Sea. Annual electricity production and economic effects of 28 wave energy converters with 750kW capacity were analyzed using significant wave height and peak wave period data(created from the NOAA's NWW3 model) and InVEST software(developed by Stanford University and University of Minnesota). Annual electricity production was estimated to be up to 1,207MWh/year and at least 163MWh/year. The spatial pattern of annual electricity production showed that the sea far from land has higher wave power potential than the sea near coast. The net present value(NPV) of 28 wave energy converters was calculated by considering an operation period of 25 years. When assuming that the electricity produced from wave energy converters is transferred to onshore power plants through underwater cables, the NPV was estimated to be up to 5,883USD(6,600,000KRW) and at least -63,494USD(-71,000,000KRW). In contrast, the NPV increased up to 28,095 USD(31,600,000KRW) when assuming that the electricity is utilized in the Ulleungdo and Dokdo. In addition, it was found that the break-even line of NPV in the East Sea becomes closer towards the land according to the increment of electricity price. The NPV of wave energy converters near the Ulleungdo and Dokdo will be 88,158 USD(99,000,000KRW) if the increment of electricity price is 100KRW.