• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.49-57
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• 2013

Recently, recycling of industrial by-products and CO2 reduction have been important issues in the world. In this reason, applications and reuse of Fly ash as a binder for concrete, which is generated in thermoelectric power plant, have been one of the effective recycle methods. In order for Fly ash to be applied to concrete, Korean Standard(KS) has selected and managed quality such as $SiO_2$, fineness, specific gravity, ignition loss and activity index. However, there is a limits for activity index, whose test period required is at least 28 days or 91 days. Activity index is the critical indication standard to determine mechanical strength of concrete that contained Fly ash. To complement the disadvantage of test method, this research provided "API test method", which quickly measure Pozzolanic reaction of Fly ash can be considered as a alternative of activity index. Then, the adaptable API test method need to be investigated through comparative analysis with the test result of API, activity index and K-value. The test method can make evaluation of Fly ash quality faster and more accurate. As a result, most Fly ash produced in Korea has not been satisfied in the KS quality standard except water content and specific gravity, and especially fluidized bed boiler ash has its characteristics. Also, API, activity index and K-value have superior interrelationship. The interrelationship between API and activity index and K-value gets increased as the material age gets higher, so API test can be considered as very useful test method for Pozzolanic reaction evaluation of Fly ash.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.3
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• pp.233-244
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• 2008

A conceptual design study for a pyroprocesing facility, has been carried out in this study, which is available for the recovery of uranium and transuranic elemental group(TRU), that is, reusable as a nuclear fuel especially in a next generation-type reactor. The scale of this facility has been chosen as 20 kg HM/batch, comparatively small engineering size in order to collect scale-up data for the design of a commercial facility as well as to get operational experience. The spent fuel to be handled in this process is as follows : 3.5 % enriched uranium fuel, 35,000MWd/tU and 5-year cooled. The major items considered in the conceptual study are a building lay-out including various hot cells, safety management of the process operation in conjunction with material balance control, radiation safety, inert atmosphere control in shielded hot cells, and criticality control of uranium and TRU products.

• Journal of the Korean GEO-environmental Society
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• v.25 no.5
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• pp.39-47
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• 2024

In this study, the environmental implications of electric arc furnace steel slag, commonly used in road construction and soil reinforcement, were examined. Experiments were conducted to assess the leaching of heavy metals based on particle size and to investigate ion leaching from specimens with varying mixtures of steel slag and clay. The official waste test revealed no detectable heavy metals in the sample items. However, when subjected to leaching experiments and analyzed using ICP-OES, certain heavy metals were found. The reaction of steel slag with water, facilitated by free CaO within the slag, was identified as the cause of leaching. Results showed that aluminum, exhibiting the highest leaching rate, displayed an inverse relationship with particle size. In mixed soil containing steel slag and clay, higher steel slag content resulted in increased aluminum leaching. Nonetheless, the quantity of leached aluminum was notably lower in mixed soil compared to pure steel slag. Furthermore, leaching of other heavy metals remained within acceptable limits. These findings suggest that recycling mixed soil of steel slag and clay for road construction or soil stabilization presents reduced environmental risks compared to using steel slag alone. Utilizing such mixtures could offer an environmentally sustainable and safe alternative.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.933-935
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• 2017

This paper deals with the influence of fungi for the thermal protective cork-based exterior insulator which protect a missile system from aerodynamic loads and heating during flight of missile. We consider the adhesion of cork-based composite on the composite motor case which fabricated by filament winding process. We also consider the importance of the requirement analysis for effective, successful system development under given system conditions. In order to develop the basic requirement analysis for the thermal protective cork-based exterior insulator, an experimental requirement analysis was accomplished, and some experimental comparing results, the study for preventing fungi are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3542-3547
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• 2015

There is commonly used the full depth excavation method of sewer pipeline maintenance in Korea. This induces couple of technical and social problems like increase of construction cost and time for excavation and backfill, increase of public complains and delay of traffic, and so force. In order to overcome these problems, lots of laboratory tests were carried out for sewer pipeline of maintenance materials with trenchless methods. The testing materials are liquid and hardened polyurethane, and polyurethane CIPP. The lab tests were followed by Korean Standard. There are no side effects, like harmless to the human body and air pollution with stink. Judging from the limited test results, all the items tested were satisfied the KS criteria.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.15-20
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• 2002

Quality variation of plastic pouch packing of Changran-Jeotgal produced by improved process and conventional process were investigated during storage at 10, 20 and $30^{\circ}C$, respectively. The kind of plastic pouch used in this study were polyethylene/nylon/linear low density polyethylene (PE/Ny), polyethylene terephthalatefpolyethyleneflinear low density polyethylene (PET) and low density polyethylene (PE). In the higher storage temperature, the faster increase of$ CO_2$, concentration and volume of pouch packing in all kinds of pouch. However, the highest value of pH, L-value, volatile basic nitrogen (VBN) and viable cell counts were shown in PE, the next was PET and PE/Ny, Overall, Changran-Jeotgal produced by improved process showed a little change of physical and chemical characteristics than conventional process. From above results, relationship between quality parameters were predicted pH, L-value, VBN and sensory score were highly correlated, therefore, these parameters is expected to uses as shelf-life indicated elements in cease of plastic pouch packaging.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.520-527
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• 2020

Hwangtoh is the rich resource that accounts for about 15.0% of the domestic soil, and can be used as the admixture of concrete with Pozzolan characteristics if activated by rapidly freezing after burning with high temperature. In this study, the mortar curbs containing active hwangtoh were produced, based on the mixture for the mortar curbs sold on the market. The substitution rate of active hwangtoh were considered 10.0% and 25.0%, and the test items were selected to compressive and flexural strength tests, freezing/thawing resistance tests, accelerated carbonation tests, and accelerated chloride diffusion tests. In the results of the mechanical performance, it was showed that the highest strength was evaluated in OPC mixture, and the increase in strength was small by the increase of age, which was believed to be due to the fact that most of the strength in each mixture was created in three days of steam curing. The results of the freezing/thawing tests for 28 aged days showed the reduction rate of compressive strength was 85.0% or higher for all specimen, meeting the criteria presented. The accelerated carbonation tests were carried out on the specimen at 28 days of age, and the results showed that the mortar with active hwangtoh had lower carbonation resistance performance than mortar with OPC. The passed charge of each mixture was assessed in accordance with ASTM C 1202 on 28 and 91 aged days. The OPC mixture had "Low" rate and the mortar with active hwangtoh had "Moderate" rate. So it was thought that the mortar with active hwangtoh had appropriate resistance performance for chloride attack.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.270-279
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• 2018

Purpose: The aim of this study was to assess the patients' perception, acceptance, and preference of the difference between a conventional impression and digital impression through questionnaire survey. Materials and Methods: Thirteen (6 male, 7 female) subjects who experienced both digital and conventional impression at the same day were enrolled in this study. Conventional impression were taken with polyvinylsiloxane and digital impression were performed using a newly developed intra-oral scanner. Immediately after the two impressions were made, a survey was conducted with the standardized questionnaires consisting of the following three categories; 1) general dental treatment 2) satisfaction of conventional impression 3) satisfaction of digital impression. The perceived source of satisfaction was evaluated using Likert scale. The distribution of the answers was assessed by percentages and statistical analyses were performed with the paired t-test, and P < 0.05 was considered significant. Results: There were significant differences of the overall satisfaction between two impression methods (P < 0.05). Digital impression showed high satisfaction in less shortness of breath and odor to participants compared to conventional impression. The use of an oral scanner resulted in a discomfort of TMJ due to prolonged mouth opening and in lower score of the scanner tip size. Conclusion: It was confirmed that the preference for the digital impression using intraoral scanner is higher than the conventional impression. Most survey participants said they would recommend the digital impression to others and said they preferred it for future prosthetic treatment.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1756-1761
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• 2006

본 연구의 목적은 임진강 유역을 대상으로 2005년에 발생한 유출특성을 분석하는데 있다. 임진강 유역은 유역전체 면적중 2/3이상이 북한지역에 위치하고 있어서 전체적인 수문관측 자료를 수집하기 어려운 상황에 있으나, 가용한 수문관측 자료 및 유량측정성과를 이용하여 5개 지점에 대한 유출특성을 분석하였다. 임진강 유역에서는 30분 단위의 연속적인 우량 및 수위관측(건설교통부)을 하고 있으며, 기상청에서는 1시간 단위의 기상관측을 하고 있다. 우량 및 수위자료의 수집과 검토를 통하여 유역면적우량과 5개 수위관측소의 수위를 최종 확정하였다. 그리고 2005년에 측정한 유량측정성과를 통하여 유량측정성과에 대한 불확실도, 기본 수리특성 분석, 수위-유량관계곡선식을 개발하여 유량을 산정하였다. 산정된 유량은 월별, 주요 호우사상별 유출률 분석을 통하여 합리적인 유출률 범위내에서 재 조정절차를 거쳐 최종 유량을 확정하였다. 산정된 유출률은 57.0%(영중)${\sim}$72.1%(적성)의 유출률을 보였으며, 2004년 임진강 유량측정용역 보고서의 유출률과 비교한 결과 일부지점을 제외하고는 비교적 일치하는 것으로 나타났다. 임진강 유역의 일부인 설마천 시험유역에서의 2005년 연간 유출률은 60.9%로 상기의 값은 매우 타당하다고 할 수 있다. 그리고, 남북한 수문자료의 공유 및 기술적 교류, 유역 전체의 정밀한 수문관측 및 신뢰성 있는 수문자료 생성이 이루어진다면 보다 정확한 유출특성 거동을 분석할 수 있을 것이며, 효과적인 치수 및 이수계획의 수립 등 수자원 개발을 위한 기반을 확보할 수 있을 것이다.수리모형실험과 연계하여 댐 설계에 효율적으로 사용될 수 있을 것으로 전망된다.지는 것으로 평가되었다. 그러나 본 연구결과를 통하여 투수성 포장과 지하수에 관련된 매개변수의 집적과 분석결과는 현장기술 적용 시 매개변수의 유용한 선택과 도시유역의 물 순환 건전화 대안기술 적용에 효과적인 방법론을 제시할 수 있을 것으로 사료된다.첨두홍수량을 저류하기 위해서 상대적으로 넓은 저류면적이 필요한 것으로 나타난다. 대등한 수위감소값의 홍수저감효과를 발휘하기 위해서 본 연구에서는 On-Line 저류지 면적은 Off-Line 저류지에 비 두배 이상이 필요한 것으로 보여졌다.들에 관한 정보는 종종 현장관측에서 조차 무시되는 경우가 많다. 이에 본 연구에서는 수질모형의 매개변수 중 특히 수리특성에 관련된 매개변수들이 수질에 미치는 영향을 파악하는 것을 목적으로 하고 있다. 이를 위해 적용된 수질모형은 QualKo를 사용하였으며, 대상 하천은 낙동강 본류 경남구간 시점 부근인 회천 합류 전부터 낙동강 본류 경남구간 종점 부근인 밀양강 합류 전까지의 경남 오염총량관리 기본계획 시 구축된 모형 매개변수를 바탕으로 분석을 수행하였다. 일차오차분석을 이용하여 수리매개변수와 수질매개변수의 수질항목별 상대적 기여도를 파악해 본 결과, 수리매개변수는 DO, BOD, 유기질소, 유기인 모든 항목에 일정 정도의 상대적 기여도를 가지고 있는 것을 알 수 있었다. 이로부터 수질 모형의 적용 시 수리 매개변수 또한 수질 매개변수의 추정 시와 같이 보다 세심한 주의를 기울여 추정할 필요가 있을 것으로 판단된다.변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.1-7
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• 2004

Roads, like bikeways, parkways and walks, are to be just capable of supporting light traffic and traveling public, but they are required to be human friendly and environmental-oriented. Lately soil-solidifier mixture, a kind of soil-cement, has developed and has been applied to the recycling and environment-oriented pavement as the surfacing material. Soil-solidifier pavement structure has been designed by only experience. To design this pavement mechanically, it is necessary to find out basic engineering properties of soil-solidifier mixture. This study focuses on finding out mechanical characteristics of the mixture according to mixture proportions and aging. Test molds with various mixture proportions are made, and then unconfined strength tests are performed for test molds with aging of the mixture. As the result of this study, it is found that the strength of the mixture increases with amount of cement and that maximum strength is achieved at 6%$\sim$8% of the ratio of solidifier and water. The strength increase rapidly until 14 days, after then slowly. After 28 days the strength of the mixture approaches to the constant value. The heat of hydration during curing of the mixture is measured no significantly. It also shows that temperature characteristics of the mixture is similar to that of soil. Since this mixture is mixed with soil and is able to improve engineering problems in pavement due to temperature, this mixture is expected to use effectively in the environment-oriented pavement for light traffic.