• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.28-30
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• 2020

우리나라 해역은 크게 동해, 서해와 남해로 나뉜다. 해역별 특성은 공간적 및 유체역학적으로 상이하여 해역별 수중거주시설의 설계에 있어 서로 다른 주요건과 시설구성을 필요로 한다. 본 연구는 거시적 수중주거시설 설계기술 연구의 일환으로서 특히 해역별 공간 특성을 잘 갖춘 3곳의 입지 후보지(동해:Phoenix point, 남해:South Brother point와 서해:Mud point)에 대하여 요구되는 해역별 설계 환경부하를 최근 태풍Haishen, 태풍Maysak과 태풍 Bavi의 기상 예측자료 및 관측자료를 통해 비교하고 가정한 건축목표(Phoenix point: 속초시에 탈탄소 전력공급, South Brother point:부산항 수소연료 비축기지 및 해상 수소충전소, Mud point:에너지 자립형 기후중립 수산양식 기지)에 부합하도록 시설구성을 제안함으로써 우리나라 연안의 천해와 심해에서의 수중거주 가능성을 조사했다.

• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.131-138
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• 2019

Recently, there are many structures exposed to severe outdoor environments, which results in rapid degradation of durability of the concrete structures. there can be rapid deterioration of the concrete structures from early frost damage due to the insufficient curing in low outdoor temperature condition. The objective of this study is to investigate the effect of thickness change conditions and binding material on early frost damage depth of the concrete exposed to cold weather in winter, and is to clearly assess damage depth of the concrete structure due to early frost damage. Specimens with 300x300x(150, 200, 250, 300mm) were prepared. OPC and OPC+FA+BS were adopted for binders. Test results indicate that the depth of the early frost damage was deeper with the decrease of thickness of members. The brightness of specimens were reduced when the member thickness was thinner. When determining the depth of early frost damage, it can be distinguished into dark color and relatively bright color when dried for approximately 30 minutes in the indoors of $20^{\circ}C$ in temperature and 60% in relative humidity after submerging in water for 24 hours. The dark colored part can be determined easily when measured with vernier calipers.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.427-438
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• 1999

Differential growth of Ulva pertusa Kjellman was observed in response to different photon irradiances and seawater. Growth rate of U. pertusa cultivated in the seawater collected from the East Sea was significantly higher than that in the seawater collected from the Yellow Sea. Optimal growth was found at $100{\mu} molm^{-2} s^{-1}$ in both cases. Chlorophyll contents of U. pertusa grown in the east sea water were higher than that cultivated in the west sea water at irradiances lower than $60{\mu} molm^{-2} s^{-1}$. At irradiances higher than $100{\mu} molm^{-2} s^{-1}$, there was no difference in chlorophyll content in between the two different sea waters with tendency that pigmentation decreased with increasing photon irradiances. Nitrate concentration in the west sea water was 2-fold higher than that in the east sea water, while phosphorus concentrations (0.03 ppm) were similar. Concentrations of $Cu^{2+}$ and $Pb^{2+}$ were 0.004 and 0.003 ppm respectively which are far below environmental standard concentrations (0.02 ppm for $Cu^{2+}$ and 0.1 ppm for $Pb^{2+}$). Taking those data into account, we have done laboratory investigations into the effects of inorganic nutrients and heavy metals on U. pertusa. As nitrate concentration increased from 0.5 to 5 ppm, growth rate of U. pertusa increased, but different concentrations of phosphorus did not cause any differential effect. On the other hand, chlorophyll contents increased with increasing phosphorus concentrations. Copper of U. pertusa be toxic decreased the growth and pigmentation as the concentration increased, whereas lead showed no such effect. Concentrations of $Cu^{2+}$ employed in the present study were much higher than those in ambient seawater. Intermittent soaring of $Cu^{2+}$ level as observed in natural seawater could, however, seriously damage the growth behaviour of U. pertusa.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.288-289
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• 2000

일반적으로 수산자원생물은 본능적으로 자기 자신에게 가장 적합한 환경에서 생활하게 되며 또한 이런 적합한 환경이 재생산력을 높여 각 개체군의 번영을 조장한다. 각 개체군은 수온, 염분, 투명도, 해류, 해저지형, 저질, 먹이생물 등의 호적한 조건을 가진 장소로 찾아 이동하거나 모이게 되며, 주로 성장기의 먹이를 찾는 색이회유나 성숙에 따른 산란회유, 겨울을 지나기 위한 월동회유 등을 계절에 따라 반복하게 된다(Hardoen Jones, F.R., 1968). (중략)

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.969-974
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• 2008

This study was carried out to investigate the service life of reinforced concrete structures for durability design. The service life has three aspects physical service life, functional service life, and social service life, and that a structures are normally demolished to end its service life when either the functional or social service life is over before the physical service life comes to end an end. In the future, it is very important that durability design shall be performed establishing design service life and the unallowable state of deterioration in the course of design service life.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.748-750
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• 2003

정보 인프라가 제공됨에 있어서 정보보호를 위한 암호화의 중요성이 강조되고 있다. 기존의 유선 인터넷환경에서 EDI의 전자서명과, 기밀성 서비스는 RSA 방식을 동해 이루어지고 있다. 이러한 유선환경의 방식을 무선환경에 적용시키기 위해서는 여러가지 제약조건으로 인하여 속도, 데이터 교환 및 암호화 알고리즘의 적용에 있어서 문제점이 야기된다. 본 논문에서는 무선 환경에서의 효율적인 암호화키 관리를 위한 EKCS(Encryption Key Control System) 시스템을 제시한다. EKCS 시스템은 적은 메모리와 제한된 환경에서의 처리능력을 가진 무선 환경에 적합한 ECC 암호화 알고리즘과 무선환경에서의 제약성을 극복하고자 데이터의 폭넓은 활용성을 가진 XML문서를 사용한다. 본 논문은 무선환경에서 컴포넌트 기반의 다중 계층 구조를 갖는 암호화 키 관리 시스템을 설계 및 구현한다.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.371-372
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• 2000

방선균은 생리활성물질의 탐색원으로서 많은 주목을 받고 있는 미생물이지만 현재까지 이용되어온 균주의 대부분은 육상의 토양에서 분리된 것들이고, 해양의 방선균에 관하여서는 아직까지 거의 연구되지 않은 분야이다. 미생물의 서식지로서 해양의 환경조건은 육상과 현저히 다르기 때문에 해양에 있어서 방선균의 microflora는 육상과는 상당히 다를 것으로 생각되어지며, 또한 연안해역에 존재하는 방선균 중에는 육상에서 유입된 담수 등으로 인하여 육상의 토양으로부터 유래된 방선균도 많은 것으로 알려지고 있다. (중략)

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.4
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• pp.158-177
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• 2023

An estuary is a transitional water area that links the land and sea through rivers and streams, transporting various components from the land to the sea, which plays an important role in determining primary productivity in the coastal environment, and this coastal ecosystem captures a huge amount of carbon into biomass, known as blue carbon, which mitigates climate change as a potential carbon reservoir. This study examined the variation of mean grain size and organic carbon content of the surface sediments for 6 years and analyzed their relationship in the western and southern estuarine areas (Han River Estuary, Geum River Estuary, Yeongsan River Estuary, Seomjin River Estuary, and Nakdong River Estuary) and the East Sea upwelling area. During the sampling period (2015 to 2020), seasonal variation of both properties was not observed, because their variations might be controlled by diverse oceanographic environments and hydrographic conditions within each survey area. However, despite the synoptic problem of all samples, the positive relationship was obtained between the averages of mean grain size and organic carbon content, which clearly distinguishes each survey area. The unique positive relationship in all estuarine areas implies that the same process by sediment clay particles is important in the organic carbon accumulation. However, additional important factor may be expected in the organic carbon accumulation in the East Sea upwelling area. Further necessary data (sedimentation rate, dry bulk density etc) should be required for the estimation of carbon stock to evaluate the major estuaries in Korea as potential carbon reservoirs in the coastal environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.122-129
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• 2002

An optimization of satellite honeycomb platforms under sever space environment is performed. There are many optimization constraints for space environment to be considered. A modified method of feasible direction and a genetic algorithm are used to optimize the satellite platform structures. The design constraints are concerned with bearing stresses at joints and natural frequencies. The results from the optimization methods are compared. The numerical results show that natural frequency constraints are dominant to reach the optimum design. This study verifies the design of satellite honeycomb platforms and suggests an optimal platform design.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.1
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• pp.18-29
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• 2019

ROV surveys were conducted using 500 meter mini class ROV with HD video camera, 2 LED lights, a simple manipulator and 8 thrusters near the Dokdo and Simheungtaek seamount. Total six dives have been conducted using the ROV "V8 SII" from Sweden and ROV's support ship, "KOSAL V" at 4 stations between 45 and 370 meters with diving time ranged from 30 to 120 minutes. Dense communities of sea anemone (Actinostolidae sp.) and ophiuroids (Ophiuridae sp.) on the surface of rocky bottom and snow crab on the soft bottom with muddy-sand were observed at northwestern part of Simheungtaek seamount. We obtained the following results 1) habitats information for snow crab, one of the major fisheries resources, and deep-sea fauna, 2) observation on the specific topography and sediment conditions, 3) observation of the seabed surface covered with the discarded fishing gears. This study represents the first report of in situ visual observation of deep-sea organisms and their habitats near the Dokdo slopes and flat top of the Simheungtaek seamount in the East Sea. These results indicated that immediate oceanographic survey using the mini class ROV is available in the East Sea.