• Journal of the Korea Concrete Institute
• /
• v.20 no.4
• /
• pp.415-421
• /
• 2008

Reinforced concrete starts to corrode when the chloride ion concentration which is the sum of included in concrete and penetrated from environments exceeds a certain level of critical chloride concentration. Therefore each country regulates the upper bounds of chloride amount in concrete and the regulations are different for each country due to its circumstances. In this study, the critical threshold chloride content according to unit cement amount is empirically calculated to propose a reasonable regulation method on the chloride amount. As a result, the critical threshold chloride content increases considerably according to cement content and it agrees with the established theories. The present regulations on total chloride amount 0.3 or 0.6 kg chloride ions per $1\;m^3$ of concrete does not reflect the influences of mix design, environmental conditions and etc. So it can be said that it is more reasonable to regulate the critical threshold chloride content by the ratio of chloride amount per unit cement content than by the total chloride content in $1\;m^3$ of concrete.

• The Journal of Engineering Geology
• /
• v.17 no.1 s.50
• /
• pp.125-133
• /
• 2007

The environmental and geotechnical properties are investigated to the 8th landfill area made of only sewage sludge in Nanji-Do. To do this, the soils are sampled in this area, and leaching tests, heavy metal content tests, and so on are performed to research the environmental properties. As the result of heavy metal content tests, Pb, Zn, Cu, Ni, Cd and Cr were leached from the sewage sludge. Because the leaching concentration of Cu is more than the standard value of California state, Cu content have to bring down during the recycling of the sewage sludge. Meanwhile, a series of tests concerning specific gravity, liquid and plastic limits, compaction, permeability and shear strength is performed to research the geotechnical properties. The sewage sludge is consisted of sand, silt and clay, and is classified into non-organic silt or organic clay with 42.3% of plastic index. As the result of compaction test, it is expected that the compaction effect according to variation of water contents is low relatively because the dry unit weight is low and the curve of compaction forms flatness. Also, as the result of direct shear tests, the cohesion is $0.058kg/cm^2$, and the internal friction angle is $14^{\circ}$. Taking everything into consideration, the various problems are happening in case of recycling the sludge like the cover layer of landfill and so on because the compaction is bad, and the shear strength is low. Also, it is expected that the ground water pollution caused by leaching the heavy metal into the sludge. To do recycling the sewage sludge in this site, supplementary and treatment programs should be prepared.

• Environmental and Resource Economics Review
• /
• v.29 no.3
• /
• pp.363-388
• /
• 2020

The purposes of this study are to not only estimate optimal harvests and efforts using the surplus production methods for Spanish mackerel caught by multiple fishing gears, but provide dynamic optimal fisheries management for these gears using the current value Hamiltonian method. To achieve the above purposes this study uses several models such as Gavaris's general linear model for standardizing fishing efforts, surplus production method for estimating biological and technological coefficients, current value Hamiltonian method for estimating dynamic optimal harvest and efforts, and sensitivity analysis for diagnosing economic influences of these fisheries. As a result, this study showed that Spanish mackerel was overfished by multiple fishing gears based on surplus production method and the current value Hamiltonian method. Also, this study found that when the price and cost proportionally changed, the optimal harvest and fishing effort sensitively responded to the stock level of Spanish mackerel. Next, this study suggested that the multiple fishing gears for Spanish mackerel should reduce unnecessary costs such as operating time or inefficient fuel consumption. Finally, this study provided reasons Spanish mackerel should be included in the TAC system in a view of profit maximization based on sustainable use of the Spanish mackerel.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1979.10a
• /
• pp.234-236
• /
• 1979

인구의 도시집중과 고도산업사회 건설에 필연적으로 수반되는 도시하수 및 산업폐수등은 하천을 심각하게 오염시켜 하천수가 지니고 있는 자정능력 한계를 초과하고 있어 재생될수 없는 상태이므로 수자원의 보호가 요청된다. 이런 상황의 하천오염 증가 추세와 주요 오염원 및 오염물에 대하여 고찰하고 대책에 방향을 제시한다. 먼저 전국의 급수 현황과 장래를 보면 다음과 같다. 한편 수도권 한강수계를 오염시키는 주요 오염원인 폐수를 보면 주거지의 생활하수, 상업행위로 발생되는 폐수와 공장의 산업폐수로 대별할 수 있으며 수도권 한강에 유입 되는 지천 수질을 보면 다음과 같다. 위와 같은 상태의 총폐수량은 280만톤인데 비하여 청계, 중량하수처리장과 서부 북부 동부분뇨처리장의 일일 처리능력은 16.4%에 불과하다. 한편 서울지역 오염원구성비를 보면 다음과 같다. 이런 계속적인 오염물은 1977년 경우 갈수기에 80~100t/sec의 하천유량으로 희석되고 있어 자정능력 한계를 벗어나서 하류의 물은 혼탁하고 용존산소의 고갈현상을 초래하고 있다. 그러므로 도시 하천에서는 수류침체로 인한 하상퇴적을 방지하여 국소적 오염의 심화를 방지하며 유량을 증가 시켜야 한다. 수도권 한강 수계의 수질의 일부는 다음과 같다. 한편 생활수준의 향상과 더불어 수요가 급증되며 처리장의 효율과 하천수의 수질을 악화시키는 합성세제의 총생산량은 1971년에 21000톤이던 것이 1978년에는 약 50,000톤에 이르고 있으며 이중 55~60%가 서울지역에서 소모되는 것으로 추산되어 진다' 결과 한강수에서 검출되는 합성세제의 오염 현황을 보면 다음과 같이 이미 몇개 지점에서는 세계 보건기구의 허용량인 0.5ppm을 초과 하고 있는 실정이다. 또한 오염의 연쇄현상을 나타내는 중금속의 일종인 csduium의 검출 정도를 보면 다음과 같다. 이상의 하천오염에 따른 수중생태계의 변화는 물리적 화학적 생물학적 환경요인이 복합적으로 작용하는 세부적 기계에 대하여는 규명되지 않은 문제가 아직도 많으며 지표생물의 표현형은 중요한 가치를 부여하고 있다. 식물성 plankton의 우점종의 출현 빈도에 따른 수질계급을 보면 뚝섬지역 BOD 3.3~5.3 빈부수성 $~\alpha$ 중부수성, 보광동 BOD 6.0~10.3중부수성, 제 2한강교 BOD10~28 $\alpha$ 강부수성, 난지도 BOD29 $\beta$ 강부수성 등이며 이와 상이한 결과도 보여주고 있다. 이상으로 볼 때 1) 가정하수의 질을 높이기 위하여 분뇨정화조 의 효율증대 2) 산업폐수의 공정별 폐수량의 조절 및 폐수성 상에 따른 총량규제에 대비한 효율증대 3) 하천의 오염부하와 자정능력 최대한 부여 4) 폐수처리를 위한 미생물제개발 및 오염지표 종 연구와 오염내성 생물의 연구등이 종합적 으로 수행되어야 한다. 5) 이상의 모든 조사와 연구결과를 객관적으로 표기할 수 있도록 하천의 이정표가 정해져야 하겠다.

• Journal of Advanced Technology Convergence
• /
• v.2 no.4
• /
• pp.13-19
• /
• 2023

Following the signing of the Paris Agreement on Climate Change (UNFCCC, 2015), the world is expanding greenhouse gas reduction activities through comprehensive participation that includes not only developed countries but also developing countries. Major countries around the world are placing high expectations on the effectiveness of total carbon emissions regulation through the carbon emissions market. However, in order to obtain carbon credits, third-party verification is required based on quantitative carbon reduction data. Accordingly, in this paper, we developed an AIoT high-efficiency street light for carbon emissions and conducted a performance analysis study to measure the luminous efficiency of the lighting fixture. To obtain carbon emissions rights, we used high-efficiency LED PKG, developed our own high-voltage PFC, and developed high-efficiency lighting fixtures capable of communication. For communication, the 2.4GHz LoRa method was adopted between the lighting fixture and the gateway. Lens design was conducted through simulation of Korea Expressway Corporation's standard streetlight types A, B, and C. The performance of the streetlight was verified as being more efficient than other existing products through the measurement of luminous efficiency by an accredited rating agency, and it is expected that carbon emissions rights will be obtained by reducing electrical energy through this.

• Journal of Korean Society of Transportation
• /
• v.21 no.1
• /
• pp.41-49
• /
• 2003

Marine traffic management could be defined as the implementation of managerial technical measures to improve vessel traffic safety. The managerial elements of vessel traffic management for ports and harbours or narrow channels include the total amount of traffic control, the vessel traffic separation scheme, speed restriction, traffic control by signals, the navigation information service and so forth. This research aims to quantify how much the traffic separation schemes(TSS) contribute to the alleviation effect of ship handling difficulty and to propose a design standard when the individual management measure is applied in an actual waterway. Traffic separation schemes have now been established in most of the major routes and congested waters of the world, and the number of collisions and groundings have often been dramatically reduced. In this part, the relationship between the alleviation of ship handling difficulty and the reduction of encounter figures among ships is quantitatively clarified by applying the ES model. As results of simulation analysis, it is recognized that a traffic separation system is most effective in the case of narrow width and heavy traffic volume. The centre buoy installation reduces about 1/4 of the alleviation of ship handling difficulty, TSS establishment 1/3, and design change to one-way traffic from two-way traffic reduces 1/2.

• Environmental and Resource Economics Review
• /
• v.20 no.4
• /
• pp.689-733
• /
• 2011

This study evaluates a novel scheme to trade sulfur dioxide emission permits subject to non-uniform rates. These rates are based on generators' marginal costs of compliance with environmental policy in a hypothesized least social-cost solution. This scheme is compared against the existing trading program used by the U.S. Environmental Protection Agency, featuring permits tradable one for one. Both policies are modeled to yield identical aggregate emissions. A numerical partial-equilibrium model of the U.S. energy industry is used to infer sulfur dioxide concentrations and health damages, as well as producer and consumer surplus, under the two policies. Regional pollution levels are found to vary across the two policies significantly. The system of exchange rates is estimated to outperform the uniform-trading scheme by $2.2 billion in industry profits and $2.1 billion in health damages, but to reduce consumer surplus by $6.7 billion. Paradoxically, exchange rates are thus estimated to lower total welfare by $2.5 billion. This is due to conceptual mechanism-design problems, as well as empirical issues.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.2
• /
• pp.351-359
• /
• 2019

In order to improve the problem of parking which is getting worse day by day, the municipality carries out a survey on the actual situation of the parking lot supply and demand periodically according to the related law. However, in the existing evaluation method, the parking demand that occurs under the condition that the demand is suppressed by the parking supply and regulation due to the limit of the survey method is investigated. In addition, the analysis is conducted only for the present year, and prediction and analysis of future parking problems are limited. Therefore, we propose a method to evaluate the status of parking supply and demand, which is differentiated to improve the problem of the existing evaluation method. As a result, comparing the existing method with the improved method, it can be seen that the improved evaluation method can be useful for establishing the long-term parking policy for the improvement of parking problems.

• Archives of design research
• /
• v.20 no.3 s.71
• /
• pp.191-202
• /
• 2007

In these days, open signboard system is controlled by administrative policy and law, but there is no consideration for different types of building. As such, this study aims to propose planning criteria for streetside commercial buildings, such as elevation and mass design of buildings, layout of signboard attached to the building elevation with consideration for streetscape. In mass planning for streetside commercial buildings, the building type with front open space keeps lower open signboard density than the building type directly leading to the street. It is desirable that open signboard of lower floor part is attached by a horizontal type, open signboard of low medium floor part by a projected vertical type, open signboard of high medium floor part and roof part with a minumum attachment of open signboard. As for elevation planning relative to open signboard, it is desirable that an irregular wall type is more useful than a regular wall type to control open signboard. And in all cases, horizontal element facade has a handicap to control the quantity of signboard. If the building has a corner, the piloti should be used in the corner of lower story for smooth circulation of pedestrians and emphasizing the transparency of elevation. Specially, in the case of a round corner, the corner should be emphasized by the composition of high transparent mass.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.9 no.4
• /
• pp.193-202
• /
• 2006

The Consultative Meeting of the Convention on the Prevention of Marine Pollution by Dumping of Wastes and other matter, 1972 (London Convention 1972) has requested to International Maritime Organization (IMO) Marine Environmental Protection Committee to collaborate and help clarify a boundary issue between International Convention for the Prevention of Pollution from Shops, 1973 as modified by the Protocol of 1978 (MARPOL) and the London Convention concerning 'dumping' versus 'discharges' during normal operations of ships in 2004, and subsequently established a Joint London Convention/MEPC Correspondence Group. The Contracting Parties to London Convention expressed their environmental concerns on the broad interpretation of the "cargo-associated wastes" by the States, which could be discharged by ships under MARPOL. Regulatory regimes for the cargo residues appear to vary among states. Some countries require fur ships to discharge their cargo wastes into the port reception facility and IMO also recommends doing so. This paper examines the related current national and international legal texts for the regulation of disposal of wastes from ships in order to analyze the current global concern on the marine pollution associated with waste discharge during operations of ships. In particular, we attempt to evaluate the likely marine environmental consequences arising from the disposal of cargo residue using an hypothetical case for the coal cargo residue among bulk cargos in this paper, since location, magnitude and frequency of the discharge of coal cargo residues into the sea adjacent to Korean Peninsula are not readily available. The cargo residues may be discharged to the sea according to MARPOL 73/78; however, its marine environmental consequences can be significant depending upon the characteristics and amounts of wastes to be discharged. Also the public tolerance of the environmental consequences would be widely different among nations. Multilateral environmental agreements, in general, more strictly apply their rules if there are other options to disposal at sea, i.e. port reception facility in this case. Therefore, port reception facilities for the wastes generated by ships are recommended to be further constructed in major national ports in order to reduce the risk of environmental damages during the operations of ships.