• Journal of the Korean Geotechnical Society
• /
• v.19 no.2
• /
• pp.65-74
• /
• 2003

Most of land reclamation projects are being implemented along the south and west coastal lines of the Korean Peninsula. The earth structures and in-ground LNG tank, and buildings can be constructed using artificial freezing method on the reclaimed land to control the uplift pressure caused by capillary forces. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable frost heaving pressure was developed. Decomposed granite soils, silty soil, and sandy soil were used in the laboratory freeze test which is sometimes subjected to thermal gradients under closed-systems. A major concern has been the ability to predict the frost heaving pressure over the results of relatively short-term laboratory tests. The frost heaving pressure arising within the soil samples and the temperature of the samples inside were monitored with time elapse. The degree of saturation versus heaving pressure curve is presented for each soil sample and the maximum pressure is closely related to this curve. TDR apparatus was used to measure the volumetric water content by the measurement of unfrozen water contents of frozen soils. Unfrozen water increased in soils containing a high percentage of fine-grained particles. In fine-grained soils with strong attractive farces between soil grains and water molecules, additional water is attracted into the pores leading to further volume changes and ice segregation.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.3
• /
• pp.227-234
• /
• 2018

Concrete mix design controls the various concrete properties such as workability and strength. Fresh concrete requires workability and the hardened concrete requires compressive strength. If using the concrete from different supplier concurrently, the concrete placed can show different properties unlike originally designed. However most of construction sites place the concrete from several companies. One of the predictable problems is whether the ultimate performance of concrete achieves the originally designed performance after placing the concrete from several companies. Therefore this research aims to keep the concrete quality in the above cases. This research has been done through literature review, questionnaire and the verification at the sample construction site. A literature review describes the general characteristics and quality control of concrete and a questionnaire describes the awareness and implementation of Korean Construction Specification(KCS). The production capacity and the delivery capacity of concrete suppliers is smaller than the daily quantity required on the sample site, therefore the placing of the concrete with different mixing ratio is inevitable and it can not keep the KCS. As a conclusion, this research proposed 5 alternatives and one of them has been adopted, i.e. to unify the concrete mix design of multiple concrete suppliers.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.3
• /
• pp.259-266
• /
• 2018

In recent years, the early strength of concrete is important in order to shorten the time of form removal at the construction site. The purpose of this study is to analyze the moment of form removal as investigating the amount of cement contents and the physical properties and strength of the concrete according to types of admixture in the curing temperature of $10^{\circ}C$ for concrete of 21 to 27 MPa. As a result, it was found that compressive strength of concrete could not be secured 5 MPa by 36 hours even if the amount of cement contents were increased to $360kg/m^3$ with plain admixture. Also, it was confirmed that the strength improvement rate was excellent when using the accelerating agent with polycarboxylic acid type, and the moment of compressive strength of 5 MPa was estimated at 30 hours.

• Journal of the Korean GEO-environmental Society
• /
• v.17 no.1
• /
• pp.13-19
• /
• 2016

Soft ground stabilization is needed to construct large civil facilities on the soft clay ground. Pre-loading method, which is accelerating consolidation method, is generally used to stabilize the soft ground. However, pre-loading method is required long construction period and quantities of fill material. Therefore, electro-osmosis method is used to replace pre-loading method for stabilizing the soft ground. Electro-osmosis method is disadvantageous in constructive and economic aspects because it is needed a metallic electrode. So, in order to solve the those disadvantages, plastic electrode was developed to replace metallic electrode. Plastic electrode, which is made by using nano-technology on existing Plastic Drain Board (PDB), was used to supply the electric power. In this study, therefore, the model test was conducted to confirm the effect of improvement and electrical characteristics of soft ground by spacing of plastic electrode. The result shows that the effect of improvement of soft ground was decreased up to 45% by increasing electrode spacing and electrical characteristics on the soft ground were influenced by consolidation settlement with electrode spacing.

• Archives of design research
• /
• v.17 no.4
• /
• pp.233-240
• /
• 2004

Living in the modern age with well-developed scientific technologies, all of us are enjoying convenient lives because of 'energy'. Korea, poor in resources, is importing a large portion of its energy sources from abroad but energy consumption shows an upward tendency due to the continuing economic growth and the improvement of living conditions. The atomic energy is considered a self-reliant, alternative energy source like our country. However, it is necessary to educate the people on and publicize atomic power generation in the face of the widespread negative recognition that the atomic power plant is a hazardous facility. The study approaches to these matters with a human-friendly and environment-friendly coloring plan in the perspective of environment coloring plan. The study aims to minimize negative images of the atomic power, while highlighting its friendly and positive images so as to enhance the confidence of the people on the atomic power and to create a clean image for the atomic power. For this goal, the study examined and analyzed cases of Japanese nuclear power plants and domestic nuclear power plants, and also carried out an on-site survey in the sites in which nuclear power plants would be constructed to extract concrete colors through the analyses of their natural environment and actual conditions. The study also carried out a survey of residents in the regions to induce their participation, and reflected the survey results to the coloring plan. The study is expected to create a stable and friendly image of the nuclear power plant through materializing its environment-friendly image and remove negative recognition that the people have on the nuclear power plant. It also attempted an external environment-coloring plan a s a strategic means for positive publicity and through this, is expected to ultimately contribute to the creation of the new images of nuclear ower plants.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.1
• /
• pp.73-80
• /
• 2008

An hydraulic experiment was carried out in an open channel flume in order to improve the technique of designing shape of the sluice used for tidal power generation, which greatly affects the economical efficiency of the construction of a tidal power plant. To predict the influence of change in the major design parameters relating to the sluice shape on the water discharge capability of the sluice, it was necessary to perform a precise experiment that is discriminated to previous feasibility studies or design projects. For this purpose, by installing various flow straighteners and rectifying structures inside the water supply system and the rectifying tank, the flow in the flume was stabilized as tranquil as possible. In addition, the measuring instruments and the location of installing them were carefully determined so as to minimize the errors intervened during the measurement of water discharge and water level. The method of estimating head difference between upstream and downstream of the sluice was also developed by taking account of the head loss due to the friction at the bottom and side walls in the flume.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.30 no.1
• /
• pp.10-18
• /
• 2018

Recently, a port city has been gradually expanding near coastal area, and many facilities for tourism and waterfront have been constructed near the shore. When storm surge developed by typhoon have occurred, coastal facilities have a lot of damage and failure with loss of life caused directly by the waves. Various barriers have been suggested to protect property and human life from disasters, they have not been widely applied though. Because they do not satisfy the recent trends that emphasize the surrounding scenery. In this study, a moveable barrier on revetment is proposed against wave overtopping. This moveable barrier has two function, sightseeing and protecting. In case of usual day, it is installed on the revetment and used observatory deck for sightseeing. When wave overtopping has occurred by storm surge, it protect coastal area through changing of flat deck to triangular barrier. The hydraulic and the structural performance of the newly proposed movable barrier was investigated through numerical analysis using commercial program. As a results, this structure has numerically good performance, and follow-up research is required through experimental tests though.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 2000.11a
• /
• pp.397-406
• /
• 2000

대부분의 국방정보시스템의 소프트웨어는 높은 가용성, 신뢰성, 신속성, 정확성 등을 요구하는 대규모이면서 복잡한 실시간 시스템이다. 이러한 국방정보시스템의 소프트웨어 개발사업에 있어서 저비용 고효율의 미개국방경영 건설을 위하고 강한 전투력을 육성하기 위해서는 국방정보시스템의 효율적인 소프트웨어 개발사법이 요구된다. 따라서, 국방정보시스템의 소프트웨어 사업관리자가 개발사업을 관리하고 감독하는데 있어서 개발자와 사용자간의 조정 및 통제 기능을 수행하고 해당 국방정보시스템의 특성을 파악하여 성공적인 사업수행을 할 수 있도록 기술적인 사업관리 측면에서 구체적이고 상세화된 방안/지침을 제공하기 위한 전문가시스템의 지식베이스 도메인 지식개발에 관한 연구이다. 기존의 국방정보시스템의 사업관리자가 경험을 동해 축적해 온 기술, 정책, 아이디어, 노하우 등에 대한 지식을 습득하고 사업 관련자료에서 제시한 소프트웨어 생명주기 단계별 방안이나 지침 등을 바탕으로 하여 식별된 사실이나 내용을 지식베이스로 구축하여 국방정보시스템의 사업관리자가 필요로 할 때 설명모듈을 거쳐 임무 및 세부활동사항을 게시하여 줌으로써 사업관리 경험이 부족하거나 사업관리자가 교체되었을 때 사업관리자들이 업무를 지속적으로 연계시켜 임무수행이 가능하도록 기초/기반 여건을 제공하고자 한다. 본 논문은 국방정보시스템의 소프트웨어 개발사업에서 소프트웨어 생명주기 단계별 사업관리자의 임무 및 세부활동사항 지원용 전문가시스템을 개발할 때 이용할 수 있도록 도메인 지식을 개발하는 것이며 논문의 결과를 활용시 기대되는 효과는 본문을 참고 바란다.의 장점을 취합하여 설계되었다. 본 시스템은 기존의 UN/EDIFACT표준을 사용하고 있는 EDI환경과 기존 VAN 방식의 EDI 중계 시스템과 연동되며, 향후 관세청의 XML/EDI 표준 시행을 미리 대비하는 선도연구로서 자리매김이 된다. 본 연구에서는 개발된 XML/EDI 통관시스템은 향후, 서비스의 최대 걸림돌이 되어왔던 값비싼 EDI 사용료의 부담에서 벗어날 수 있게 할 것이며, 저렴한 EDI구축/운영 비용으로 전자문서교환의 활성화와 XML이 인터넷 기반의 문서유통 표준으로 자리매김할 수 있는 중요한 계기가 될 것이다.재무/비재무적 지표를 고려한 인공신경망기법의 예측적중률이 높은 것으로 나타났다. 즉, 로지스틱회귀 분석의 재무적 지표모형은 훈련, 시험용이 84.45%, 85.10%인 반면, 재무/비재무적 지표모형은 84.45%, 85.08%로서 거의 동일한 예측적중률을 가졌으나 인공신경망기법 분석에서는 재무적 지표모형이 92.23%, 85.10%인 반면, 재무/비재무적 지표모형에서는 91.12%, 88.06%로서 향상된 예측적중률을 나타내었다.ting LMS according to increasing the step-size parameter $\mu$ in the experimentally computed. learning curve. Also we find that convergence speed of proposed algorithm is increased by (B+1) time proportional to B which B is

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.3
• /
• pp.112-121
• /
• 2020

In suspension bridges, hanger cables are the main load-supporting members. The tension of the hanger cables of a suspension bridge is a very important parameter for assessing the integrity and safety of the bridge. In general, indirect methods are used to measure the tension of the hanger cables of a suspension bridge in traffic use. A representative indirect method is the vibration method, which extracts modal frequencies from the cables' responses and then measures the cable tension using the cables' geometric conditions and the modal frequencies. In this study, the image processing technique is applied to facilitate the estimation of the dynamic responses of the cables using the image signal, for which a portable digital camcorder was used due to its convenience and cost-efficiency. Ambient vibration tests were conducted on a suspension bridge in traffic use to verify the validity of the back analysis method, which can estimate the tension of remote hanger cables using the modal frequencies as a parameter. In addition, the tension estimated through back analysis method, which was conducted to minimize the difference between the modal frequencies calculated using finite element analysis of the hanger cables and the measured modal frequencies, was compared with that measured using the vibration method.

• Journal of Korean Society of Transportation
• /
• v.34 no.4
• /
• pp.304-317
• /
• 2016

The advancement in technology including transportation and information communication has accelerated the flow of supplies, and the importance of the national logistics policy has increased following the expansion of the regional range of logistics to a national range. The rapid growth of the domestic logistics market results in the deficit of logistics facilities, inefficient operation of logistics facilities, and a complicated distribution structure. It has precipitated a plan aimed at efficiency improvement by building base logistics facilities, but this market is now undergoing difficulties due to low performance. Many studies on the revitalization of base logistics facilities have been conducted, but a causal analysis focusing on the function overlap of private logistics businesses has been absent. Therefore, this study has analyzed the function overlap of logistics facilities and the irrationality of the system, which resulted from the lost function of Inland Freight bases in the Yeongnam region. By suggesting the cause of disuse of base logistics complexes from the function overlap in the ground transportation of domestic freight, the study can provide the policy implication for the national logistics infrastructure.