• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.109-116
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• 2021

In order to replace mineral aggregate used as road pavement materials with steel slag aggregate, this present study evaluated mechanical properties of SMA Concrete mixtures using steel slag aggregate as oxidized slag from electric furnace in iron works. The variables of this experiment are the aggregate type of mineral and steel slag and the sieve sized of 10mm and 13mm. The physical properties inclu ding the specific gravity and absorption rate etc. of the slag aggregate mixtu res satisfied the KS standard as asphalt mixtu re. As a resu lt of evalu ating the mechanical properties of the asphalt mixtures, the optimum asphalt content of the slag aggregate mixtures were lower than that of the mineral aggregate mixtures, but other quality standards were all satisfied. In the deformation strength evaluation, the slag aggregate mixtures were measu red slightly higher than that of the mineral aggregate mixtu res, and the dynamic stability test satisfied the 2,000pass/mm standard value in all specimens. And, the moduli of resilient of the slag aggregate mixtures showed an improved value compared with the mineral aggregate mixtures. Therefore, as the resilient rate of the slag aggregate mixtures improved, it is speculated that there will be an effect of improving public performance according to the repeated traffic load of the vehicle.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.77-91
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• 2006

Domestic practices in shotcrete use have developed in many respects even now, but it still has issues about material, construction, quality standard and so on. In overseas, the construction using high strength shotcrete with $39.2{\sim}58.8 MPa$ of compressive strength is becoming common based on the shotcrete technology of high strength and durability. However, domestic shotcrete design strength is low at around 20.6 MPa of compressive strength and a long term durability is also insufficient. In this paper, field tests using high-quality additives and accelerators were performed to obtain the improvement of shotcrete strength and EFNARC standard was used to evaluate the field test results. In addition, deterioration test combined with the freezing-thawing and carbonation was also performed in order to investigate a long-term durability of high-strength shotcrete. As a result of the field test, the promotion ratio of early strength was $90{\sim}97%$ in case of using alkali-free accelerators. And the compressive strength of the shotcrete using Micro-silica fume was $45.2{\sim}55.8MPa$ and flexible strength was $5.01{\sim}6.66MPa$, so the promotion ratio of strength was $37{\sim}79%$ and $17{\sim}61%$ respectively. The promotion effect of strength by silica fine additives ratio of $7.5{\sim}10%$ for cement mass was much superior to the other cases. It was especially examined that using Micro-silica fume reduced deterioration due to mixed steel fiber and improved a long-term durability of shotcrete.

• Land and Housing Review
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• v.6 no.2
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• pp.67-77
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• 2015

Now that it is the current situation that the smooth supply and demand are necessary for 2nd phase of beginning construction and stable development of Gaesung Industrial Complex, this study was willing to offer the planning criteria and model to establish the lodging for the workers in Gaesung Industrial Complex based on the agreement that both South and North Korea agreed in 2007. Regarding the plan, its standard and the alternative were reviewed considering welfare of workers, economic efficiency, technical validity, possibility of agreement and long-term development. The exclusive area per capita was calculated through Labor Standards Act of Korea and status survey of lodging for the workers provided to border line area between China and North Korea and the economic alternative based on one room for 6 persons with the public restroom was compared with that of development type based on one room for 4 persons with indoor restroom. Especially regarding the proposed site, the area with the optimized position was set by considering gradient, accessibility and convenience of development out of the area of Dongchang-ri where was agreed already and the priority of the proposed site that can keep the existing building site and provide was offered. The necessary period for whole construction was set as approximately 36 months. Regarding construction method, RC Rahmen method was selected as the optimized alternative considering the workmanship of manpower of North Korea and conditions of supply and demand of materials and cluster-type vehicle allocation plan based on 4~6 units considering the efficiency of supplying service facilities and convenient facilities along the simultaneous accommodation of 15,000 people was offered. It was analyzed that total business expenses of approximately 80~100 billion Korean Won would required though there were the difference for each alternative in the charged rental way that the development business owner develops by lending the inter-Korea Cooperation Fund and withdraws the rent by the benefit principle. The possibility of withdrawing the rent was analyzed assuming that the period of withdrawing the investment is 30 years. Especially for the operation management after moving, the establishment of the committee of operating the lodging for the workers of Gaesung Industrial Complex (tentative name) was offered with the dualized governance that the constructor takes charge of operational management, collecting fees and management of infrastructure and human resource management is delegated to North Korea.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.333-344
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• 2022

The quarrying and utilization of natural building stones such as granite and marble are rapidly emerging in developing countries. A huge amount of wastes is being generated during the processing, cutting and sizing of these stones to make them useable. These wastes are disposed of in the open environment and the toxic nature of these wastes negatively affects the environment and human health. The growth trend in the world stone industry was confirmed in output for 2019, increasing more than one percent and reaching a new peak of some 155 million tons, excluding quarry discards. Per-capita stone use rose to 268 square meters per thousand persons (m²/1,000 inh), from 266 the previous year and 177 in 2001. However, we have to take into consideration that the world's gross quarrying production was about 316 million tons (100%) in 2019; about 53% of that amount, however, is regarded as quarrying waste. With regards to the stone processing stage, we have noticed that the world production has reached 91.15 million tons (29%), and consequently this means that 63.35 million tons of stone-processing scraps is produced. Therefore, we can say that, on a global level, if the quantity of material extracted in the quarry is 100%, the total percentage of waste is about 71%. This raises a substantial problem from the environmental, economical and social point of view. There are essentially three ways of dealing with inorganic waste, namely, reuse, recycling, or disposal in landfills. Reuse and recycling are the preferred waste management methods that consider environmental sustainability and the opportunity to generate important economic returns. Although there are many possible applications for stone waste, they can be summarized into three main general applications, namely, fillers for binders, ceramic formulations, and environmental applications. The use of residual sludge for substrate production seems to be highly promising: the substrate can be used for quarry rehabilitation and in the rehabilitation of industrial sites. This new product (artificial soil) could be included in the list of the materials to use in addition to topsoil for civil works, railway embankments roundabouts and stone sludge wastes could be used for the neutralization of acidic soil to increase the yield. Stone waste is also possible to find several examples of studies for the recovery of mineral residues, including the extraction of metallic elements, and mineral components, the production of construction raw materials, power generation, building materials, and gas and water treatment.

• Journal of the Korean Wood Science and Technology
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• v.42 no.1
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• pp.1-12
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• 2014

This study carried out life cycle assessment for evaluating environmental impacts of timber Arch-Truss bridge by using domestic Pinus rigida Miller glued-laminated timber throughout life cycle such as extraction, manufacturing, transportation, construction, use, dismantlement, transportation of waste, disposal and recycling. The life cycle GHG (GreenHouse Gas) emissions of the target bridge are 192.56 ton $CO_2$ eq. in 50 years. Especially, the life cycle GHG emissions of concrete used in the target bridge are 82.84 ton $CO_2$ eq. which accounts for 53.02% of the GWP (Global Warming Potential) in extraction and manufacturing stages. The target bridge is constructed of $116.57m^3$ of domestic Pinus rigida Miller glued-laminated timber and used timber has stored 104.72 ton $CO_2$. If an effect of carbon storage in timber is applied to the total GHG emissions of the target bridge, the GHG emissions can be reduced by 54.38%. In the case of substitution effect, if domestic Pinus rigida Miller glued-laminated timber replaces steel manufactures used in other bridge which has the same structure and life span as the target bridge, the GHG emissions in extraction and manufacturing stages can be reduced by 10.26% to 23.91%.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.47-47
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• 2011

에너지자원이 부족하여 에너지 해외의존도가 약 80% 이상인 우리나라의 특성상 에너지 해외의존도를 경감시키고 에너지부족 상황을 안정시키기 위하여 국내의 부존에너지를 최대한 활용하는 것이 필요하다. 또한 지구온난화에 대처하는 범세계적인 규제에 대비하기 위하여, 청정에너지를 적극 개발하여 에너지자립도를 향상시켜야 한다. 신재생에너지 중 하나인 소수력은 친환경적인 청정에너지 중 하나로 다른 대체 에너지원에 비해 높은 에너지 밀도를 가지고 있어 개발 가치가 큰 부존자원으로 평가되고 있다. 그리고 소수력은 여러측면의 사회적 환경적 이점으로 최근에는 선진국에서도 매우 큰 관심을 끌고 있으며, 에너지 자원이 빈약하여 대부분 석유수입에 의존하는 우리나라는 지역에너지로 소수력을 적극 개발하여야 한다. 소수력 부존량이 풍부한 우리나라는 1982년에 소수력 개발 활성화 방안이 공표되면서부터 정부주도 하에 소수력 발전소 건설에 관한 연구를 적극적으로 지원하게 되었다. 대수력과 비교하여 소수력의 장점으로는 비교적 짧은 계획 및 시공기간, 낮은 투자비용, 개인이나 기업을 통한 투자참여, 주위 인력이나 자재를 이용한 쉬운 설치, 적은 환경적인 피해 등이 있다. 이와 같이 청정에너지 중 하나인 소수력의 개발과 활용을 위하여 IT 기술을 접목한 다양한 응용시스템 구축이 진행되고 있다. 특히, 한국에너지기술연구원에서는 신재생에너지 개발 및 보급 확대를 목표로 2006년에 신재생에너지 자원지도시스템을 구축하였으며, 이를 웹상에서 제공하고 있다. 소수력 발전시설의 적극적인 활용을 위해서는 초기설계시 장기유출 특성분석을 통해 해당유역의 수자원을 최대로 활용하고, 지형적인 요소를 이용하여 전기의 생산이 최대가 되도록 하는 최적설계가 이루어 져야 한다. 따라서 본 연구에서는 소수력 발전시설의 최적설계를 위해 한강수계 258개 표준유역 중 섬강합류점에 대하여 자원지도를 활용하여 연평균유량을 추정한 후 소수력 자원량을 산정하였고, 그 결과로 시설용량과 연간전기생산량은 각각 1,633kW, 6,224MWh로 산정되었다. 또한 유출량의 미계측 유역에서의 소수력 발전성능을 예측하기 위한 방법으로 Weibull 분포의 특성화 방법을 선택하여 그 적용성을 검토하였다. 섬강합류점 표준유역 내에 위치하고 있는 목계관측소, 앙성관측소에서의 10개년(1999~2008) 강우자료를 바탕으로 유황곡선을 작성하여 상관관계분석을 실시한 결과 목계관측소에서 0.994701, 앙성관측소에서 0.992616으로 관측치와 계산값이 상당히 유사한 것으로 나타났다.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.233-236
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• 2001

일반적으로 스피커를 동작시키게 되면, 스피커 보이스 코일에 열이 발생하게 되고, 열에 의한 보이스코일의 저항의 증가가 나타나게 되는데, 기존의 연구는 저음용 스피커(Woofer) 만을 대상으로 스피커의 음향특성 변화들에 관해 수행되었다. 그러나, 현대의 스피커는 A/V시스템분야의 발전에 따라 고음재생의 충실도가 강조되고 있는 경향이므로, 고음용 스피커(Tweeter)에 대한 열 발생의 영향을 조사하였다. 본 연구에서는 고음용 스피커의 입력전력에 따른 특성 변화를 조사하고, 입력전력의 증가로 인한 보이스코일(voice coil)의 저항 증가에 따른 고음용 스피커의 특성변화에 관해 실험하였다. 그리고, 스피커의 진동에 의한 펌프(pump) 역할을 이용하는 냉각용 구멍을 뚫어 스피커의 특성변화를 검토하였다. 실험대상으로는 직경 25mm의 돔(Dome)형 진동판을 가진 고음용 스피커와 이 스피커의 후면 중심부에 구멍을 뚫어 열 방출구가 형성된 3종의 시료를 대상으로 특성변화를 비교$\cdot$측정하였다. 여기에서, 사용된 시료는 국내 Y사의 판매용 고음용 스피커로 제품의 원 상태인, 구멍이 없는 것을 기준시료로 하고, 이와 동일한 제품들의 후면에 각각 직경 5mm, 10mm, 15mm의 구멍을 가공하여 비교시료로 하였다. 기준 및 비교시료의 스피커 특성을, 한국산업규격 KS C 6027의 측정법에 따라, 입력 1W 상태에서 기준시료의 사양을 측정하였고[1], 입력을 0.5W, 1W, 2W, 4W, 8W, 16W로 가하여, 시료별 입력증가에 따른 스피커의 주파수 응답특성, 임피던스(Impedance), 조화 왜(Harmonic Distortion)의 변화율 측정을 통해 스피커의 특성변화 정도를 검토하였다. 향후, 본 연구의 결과는 고음용 스피커의 특성 열화에 대한 예측 및 개선 방안을 제시하는 기본 자료로 활용이 가능할 것으로 사료된다.용하여 현금흐름예측을 할 수 있는 Model을 제시하였다. 특히 건설공사의 현금흐름 예측의 중요한 요소인 Cash-Out에 대하여, 공사비 구성요소인 자재, 노무, 중기, 외주, 경비등 각 Resource의 보할(Weights)을 실 공사원가에 따른 보할의 변화와 Resource들의 Time Lag를 적용 기존 연구자의 Model과 다른 Model을 제시하였다. 또한 기존 연구자들의 Model과 비교하여 편리성, 정확도 및 신뢰성이 높은 Model임도 증명하였다.세대까지도 발현수준이 유지될 것으로 판단된다. 이러한 연구결과는 계통으로 확립된 형질전환 동물에 부여된 새로운 유전형질은 지속적으로 후대로 유전될 수 있음을 제시한다.잖⨀瘀Ā퀇Āゑ잖⨀Ā퀇Ԁ￿™잖⨀䌀Ā퀇ĀꄏĀꀏꄏĀꀏ₱?⨀Ā Ԁ￿䂱?⨀ऀĀ耀Ā삱?⨀؀Ā Ā?⨀ጀĀ耀Ā?돀ꢘ?⨀硩?⨀ႎ?⨀?⨀넆돐쁖잖⨀쁖잖⨀／ࠐ?⨀焆덐瀆倆Āⶇ퍟ⶇ퍟ĀĀĀĀ磀鲕좗?⨀肤?⨀⁅Ⴅ?⨀쀃잖⨀䣙熸ጁ↏?⨀

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.307-313
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• 2010

Recently in Korea, or companies considering overseas expansion is often already begun. Past, enterprise's overseas economic cooperation fund(OECF) was consisted of overseas economic cooperation fund(OECF) of most large enterprise leading but medium and small enterprises as well as large enterprise is recognized for factor that competitive power security through overseas economic cooperation fund(OECF) is indispensable by economy opening Tuesday such as deregulation of great foreign enemy environment change and a technology and capital introduction. In the case of Korea, that advance of the China is going through bottleneck among by far bank Vietnam advance gradually expand. Therefore, in this study, I wished to quote plan for efficient and desirable Vietnam advance strategy establishment regarding our country enterprise's Vietnam advance through economy, politics, social environment analysis. In this study, can do on the basis of Vietnam advance connection domestic?outside literature investigation and virtue study through theoretical investigation according to these purpose and behaved theoretical investigation and lift construction materials allied industry, labor-intensive manufacturing industry, fisheries farm produce cultivation, processing household mascot etc. as energy industry, refined oil and petrochemical industry, electric-power industry, other field by our country medium and small enterprise.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.259-265
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• 2012

Differently from fly ash, the bottom ash produced from thermal power generation has been treated as an industrial waste matter, and almost reclaimed or was applied with the additive of the part concrete. Bottom ash has various problems to use with the aggregate. Bottom ash is lighter than typically the sand or the gravel and it's physical properties (compressive strength etc.) is somewhat low because of high absorptance. In order to manufacture the ash concrete, we used a bottom ash as a main material and a pure sulfur as a binder. In this study, fundamental research methods that vary the grain-size of bottom ash and the ratio of sulfur vs ash were investigated to improve the quality of ash concrete such as compressive strength. Bottom ash in this research which occurs from domestic 4 place power plants, was checked physical and chemical properties. The compressive strength seems the result which simultaneously undergoes an influence in content of the sulfur and Bottom ash grain-size. We got the result of the maximum 92 MPa. The compressive strength was high result for grain size below 1.2 mm and high sulfur content.

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.207-215
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• 2014

As a reinforcement material for RC members, the modified epoxy mortar has been reported one of the superior materials since the material can improve the load capacity and the seismic performance of the RC members. However, there were few experimental studies and analytical research for improving seismic performance with the material. This study is to propose an effective reinforcement plan for RC Ordinary Moment Resisting Frame (OMRF) with the evaluation of seismic performance and economic analysis. For the objective, first, the load-deflection curve of a simple beam specimen was compared with the analytical results. Second, a 5-story RC OMRF structure was designed only for gravity load and the alternatives for seismic reinforcement were suggested. Third, pushover analysis was executed for evaluation of design coefficients and seismic performance of the structures. Finally, an effective reinforcement plan was suggested based on the results of quantity take-off and economic analysis. The findings of this study can be utilized as the basic data when the modified epoxy mortar is applied to practice for improving the seismic performance of RC members.