• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.2
• /
• pp.63-73
• /
• 1998

Due to the collapse of corrugated bulkheads subject to accidental flooding which is thought to be a primary cause of bulk carrier losses International Maritime Organization(IMO), the International Association of Classification Societies(IACS) and the leading classification societies are taking a growing concern for the structural safety of corrugated bulkheads of bulk carriers. To prevent progressive collapse of corrugated bulkhead in flooded condition particularly of forward cargo ho1d they try to make rules which require reinforcement of corrugated bulkhead structure. However, we are still confronted with the urgent problem of more accurate and efficient ultimate strength assessment for corrugated bulkheads. This paper develops a special purpose nonlinear FE program for analyzing progressive collapse behavior of corrugated bulkheads subject to lateral pressure loads. As verification examples, the program is applied to collapse strength analysis of steel corrugated bulkhead test model.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.19 no.4
• /
• pp.332-340
• /
• 2016

Sunken ships cause damage to the environment due to the dispersal of fuel oil and harmful cargo goods in the hull. Since the sunken ship is mostly flooded by the seabed, it tends to be in a relatively stable condition. However, the heavy body, together with the load of remaining goods in the cargo hold, the constant contact with the seabed, and ocean currents and tidal waves, can affect dispersal of residual fuel oils out of the sunken ship. Corrosion of the sunken ship starts upon sinking, decreasing the thickness of the hull structure and sub-materials. Therefore, it is necessary to assess the structural stability against the potential breakdown of the sunken ship. Whilst evaluating the danger of the sunken ship, this result should be reflected in 'the possible discharge'. This study was undertaken to suggest a procedure for a step by step evaluation to assess the structural stability a sunken ship. The structural stability assessment to estimate the collapsibility of the hull was structure targeted at the sunken ship 'No. 7 HaeSung', which was classified as the prime example for the intensive management of sunken ships. This study was undertaken to suggest a procedure for a step by step evaluation to assess the structural stability a sunken ship and to propose a method to conduct a structural safety assessment that estimates the collapsibility of the hull by targeting the sunken ship 'No. 7 HaeSung',which was classified as the prime example for the intensive management of sunken ships. The collapsibility of the hull structure was estimated Based on the damage size of the hull structure, and the corrosion rate of the hull structure and sub-materials due to the seawater after sinking. It was confirmed that there was a low possibility of the total destruction of the hull structure at the current time. However, there is a high possibility in the potential failure of the hull structure due to increased rate of corrosion thereafter. Therefore, we believe continuous study on influence of corrosion and marine environment change to sunken ship's structural safety is necessary.

• Proceedings of the KAIS Fall Conference
• /
• 2008.11a
• /
• pp.459-462
• /
• 2008

본 논문에서는 $10K_2O$-30CaO-$60P_2O_5$ mol%를 기본조성으로 하여 Fe, Cu, Zn의 미량성분을 첨가하여 유리를 제조하고 용출 특성을 평가 하였다. 제조된 유리는 미량성분의 첨가량에 따라 유리의 투명도가 변하는 것이 관찰되었다. 용출특성은 측정 4시간 뒤 pH값 증가되는 것으로 16시간 후 pH가 증가하는 것으로 관찰되었다. 여기서 pH의 증가는 염기성산화물이 용출되는 것으로, 감소는 $P_2O_5$구조인 망목형성구조가 붕괴되어지면서 산성이온이 용출되어지는 것으로 판단되어진다. ICP관찰시에는 함량이 증가하면서 K, Ca, P이온의 용출량이 감소되었고, Zn, Cu, Fe이온의 용출량이 증가하는 경향이 관찰되었다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2023.11a
• /
• pp.116-118
• /
• 2023

In recent years, the need for economical and sustainable ship routing has emerged due to the enforced regulations on environmental issues. Despite the development of weather forecasting technology, maritime accidents by rough waves have continued to occur due to incorrect weather forecasts. In this study, onboard measurements are conducted to observe the acutal situation on merchant ships in operation encountering rough waves. The types of measured data include information related to navigation (Ship's position, speed, bearing, rudder angle) and engine (engine revolutions, power, shaft thrust, fuel consumption), weather conditions (wind, waves), and ship motions (roll, pitch, and yaw). These ship experiments was conducted to 28,000 DWT bulk carrier, 63,000 DWT bulk carrier, 20,000 TEU container ship, and 12,000 TEU container ship. The actual ship experiment of each ship is intended to acquire various types of data and utilize them for multi-objective studies related to ship operation. Additionally, in order to confirm the sea conditions, the directional wave spectrum was reproduced using a wave simulation model. Through data collection from ship experiments and wave simulations, various studies could be proceeding such as the measurement for accurate wave information by marine radar and analysis for cargo collapse accidents. In addition, it is expected to be utilized in various themes from the perspective of safety and efficiency in ship operation.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.6
• /
• pp.675-682
• /
• 2015

Current design codes such as AASHTO LRFD or Korean Highway Bridge Design Code recommend of using static force for designing bridge column against vehicle collisions. However, there was an accident that the bridge was collapsed shortly after vehicle impact on bridge pier in Nebraska(near Big Spring, 2003). It was found that the second largest cause of bridge collapse is collision after hydraulic causes. It can be thought that the possibility of truck-bridge collision are getting increasing as the size of truck increases and traffic condition are becoming improved. However, dynamic behavior under the impact loading seldom considered in bridge design procedure due to computational cost and time. In this study, in order to reduce the computational cost for dynamic impact analysis, model reduction method was developed. Obtained results of residual displacement were compared with the results of direct impact simulations.

• Proceedings of the Korean Society of Disaster Information Conference
• /
• 2017.11a
• /
• pp.337-338
• /
• 2017

지난 60년간 일본, 한국, 중국은 물론이고 아시아에서의 공정 산업은 크게 성장했다. 그 발전과정에서 다양한 사고들을 겪고 극복해내는 과정이 있었으며, 최근 한국의 화학물질관리법을 포함하여 안전 기술 및 안전 관리에 많은 진전 또한 있었다. 이 발표의 서두에서는 한국의 공정산업의 역사적 발전에 대해 뒤돌아보며 당면 과제들에 대한 논의를 전개하고자 한다. 장기적인 경제발전의 일환으로 중화학공업 육성을 표방하며, 초기 단계에 정부주도의 적극적인 산업 발전 계획을 수립해 산업의 성장을 주도하였으며, 1990년대에는 어려움을 극복하기 위해 시장 중심의 구조 조정이 도입되었다. 지난 30년 동안 한국사회에서는 가스 폭발, 건물 붕괴, 화물 및 여객선의 사고를 비롯한 치명적인 사고들이 있었다. 이러한 사고 후에는 필연적으로 안전 정책 및 법률에 중요한 발전이 있었는데, 가장 최근의 것은 2012년 유독 가스 배출 사고 이후 화학물질관리법(Chemical Control Act)을 시행한 것이다. 또한 앞으로 20년간 (2036 년까지) 다양한 구성요소의 수준을 정량화할 수 있는 지속 가능성 개념에 대한 강한 요구가 있음은 주지의 사실이다. 지속 가능성의 새로운 패러다임은 에너지, 경제 및 환경의 전통적인 구성 요소로 구성된다. 더불어 지속 가능성은 안전, 보안 및 세계화(globalization)를 다루어야 한다. 미래의 지속 가능성 개념은 이러한 6가지 구성 요소 모두를 하나의 기능으로 정량적으로 통합할 것이다. 특히 이 작업에 대한 강력한 리더십은 화학 공정 산업에서 절대적으로 부족한 현실이기에, 이러한 기능의 통합과 특화된 교육 및 훈련에 대해 한국의 사례와 해외에서의 글로벌 응용 프로그램에 대란 논의를 통해 본 발표는 향후의 발전방향과 비전에 대해 논의하고자 한다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.7
• /
• pp.863-868
• /
• 2016

In this study, the precise shapes of sunken ships and information on seafloor topography were analyzed using data obtained from a multi-beam echo sounder. The state of each sunken ship was analyzed by processing diverse imagery data which was compared with data obtained from past investigations to determine changes in the state and circumjacent seafloor topography. Apparent changes in the seafloor topography around one sunken ship, the "Pacific Friend", were found from stern to bow as a result of continued submarine erosion and sedimentation. In the case of sunken ship "No. 7 Haeseong", the partial collapse of the bow was revealed in the seabed images captured in 2015, though it had still been intact in images captured during the Korea Hydrographic and Oceanographic Agency's investigation in 2011. This partial collapse was presumed to have resulted from the effects of continued tidal currents, the cargo load of the ship and continued corrosion of the ship over a long time on the seabed. Continuous monitoring of residual fuel inside the ship is necessary to avoid leakage and potential marine pollution. By conducting image analysis on these sunken ships, it has been determined that the structural safety of the ships is seriously influenced by tidal currents and seafloor topography, while the hulls will be continuously changed by corrosion. As a result, it can be concluded that the development of prediction and response techniques that take into consideration residual fuel leakage and environmental changes according to the geological characteristics of sunken ships is necessary.

• Economic and Environmental Geology
• /
• v.50 no.2
• /
• pp.105-116
• /
• 2017

The purpose of this study is to provide the information on genesis of obsidian occurring in the southwestern part of Ulleung Island, Korea, and to discuss its implications for volcanic activity through volcanological and mineralogical properties of obsidian. Obsidian occurs locally at the lower part of the Gombawi welded tuff, showing various complex textures and flow banding. Though obsidian is mostly homogeneous, it is closely associated with alkali feldspar phenocrysts, reddish tuff, and greyish trachyte fragments. The obsidian occurs as wavy, lenticular blocks or lamination composed of fragments. Cooling fractures developed on obsidian glass are characterized by perlitic cracks, orbicular or spherical cracks, indicating that obsidian rapidly quenched to form an amorphous silica-rich phase. It is evident that hydration took place preferentially at the outer rim relative to the core of obsidian, forming alteration rinds. The glassy matrix of obsidian includes euhedral alkali feldspars, diopside, biotite, ilmenite, and iron oxides. Microlites in glassy obsidian are composed mainly of alkali feldspars and ilmenite. Quantitative analysis by EPMA on the obsidian glass part shows trachytic composition with high iron content of 3 wt.%. Accordingly, obsidian formed with complex textures under a rapid cooling condition on surface ground, with slight rheomorphism. Such results might be induced by collapse of lava dome or caldera, which produced the block-and-ash flow deposit and the transportation into valley while keeping high temperatures.

• Journal of the Mineralogical Society of Korea
• /
• v.31 no.1
• /
• pp.23-32
• /
• 2018

Noerok ia a green pigment used in Joseon dynasty, and its main usage was for forming foundation layers of Dancheong, the ornamental paintings on the surface of traditional buildings in Korea, such as the Daeung-jeon(main hall) of Bulguk-sa temple. In this research, we investigated the mineralogical characteristic changes of Noerok, a traditional Korean pigment, depending on its firing temperature. The Noerok that we experimented on was mined from Noeseong Mountain, Pohang where it is locally reserved. The major composition mineral is Celadonite, and the main constituent elements are Fe, Si, K and Mg, that refers to the existence of Fe-rich mica. As a result of phased firing experiment from $105^{\circ}C$ to $1000^{\circ}C$, the color was changed from green to pale green, then to brown, and finally to red in order. In the thermal analysis, endothermic reaction induced by the dehydration of crystalline water was confirmed at around $616^{\circ}C$. In the mineralogical change, the crystal surface [($11{\bar{1}}$) and ($02{\bar{1}}$)] of the mineral collapsed at temperatures above $600^{\circ}C$, and iron oxide was formed at $1000^{\circ}C$ or higher. Therefore, it is estimated that the crystallization temperature of Noerok is below $600^{\circ}C$, and it is also considered that it has undergone the alteration phase up to stage I, based on the presence of only a celadonite.

• Journal of the Korean Wood Science and Technology
• /
• v.28 no.3
• /
• pp.34-41
• /
• 2000

Recently many scientists have tried to synthesize biodegradable polymers due to durable and non-biodegradable products of conventional synthetic plastics when these were wasted in nature. So to reuse the wastepapers for biodegradable polymer resources, ONP (old newsprint), OCC (old corrugated containerbpard) were carried out by the pretreatment of chlorinite, hypochlorite and oxygen-alkali treatment conditions. For manufacturing of biodegradable polymer with wastepaper, this study performed to investigate change of chemical components and optimal pretreatment condition. The summarized results in this study were as follows: Lignin content in ONP and OCC was was higher than in MOW and ash content was the highest in MOW. More amount of ash components were reduced by wet defiberation than by dry defiberation. Wet defiberation fiber are better than dry defiberated fiber in chemical pretreatment condition for wastepapers, and the best result was obtained in the condition of sodium chlorite at $70^{\circ}C$, because it has high delignification ratio, ${\alpha}$-cellulose contents and degree of polymerization in this treatment condition. Oxygen-alkali treatment condition is the worst method because of low yield, low degree of polymerization in this pretreatments.