• 한국치위생학회지
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• 제17권5호
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• pp.817-826
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• 2017

Objectives: The aim of this study was to investigate the effects of bamboo salts on remineralization effects on subsurface of artificial carious enamel. Methods: Incipient carious enamel was formed in permanent bovine incisors and then specimens were divided into three groups randomly: 3% bamboo salt (BS), 2% (NaF) and the solution of mixed 3% BS and 2% NaF. For remineralization, specimens of each of the three groups were treated for 24 hrs at $37^{\circ}C$ incubator. After treatment, specimens were analyzed using SEM and VHN. Statistical analysis used was one-way ANOVA. Results: In SEM observation, the BS group showed narrower distances between enamel rods than the cases of incipient subsurface caries enamel. The NaF and BS+NaF groups showed that the enamel rods near the surface were destructed, and innumerable round small particles were deposited near the surface of enamel. The BS+NaF group showed more minerals attachment between enamel rods than the cases of other groups. The differences in subsurface microhardness (${\Delta}VHN$) increased all of three groups in total by $80{\mu}m$. The ${\Delta}VHN$ of the BS+NaF group increased significantly more than NaF and BS groups in depth of $50{\mu}m$, $80{\mu}m$. Conclusions: The 3% bamboo salt with 2% NaF solution was found to increase subsurface hardness of incipient caries enamel. Thus, bamboo salt will be used to contribute to prevention on dental caries.

• 한국토양비료학회지
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• 제48권5호
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• pp.372-378
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• 2015

Growing crops under different soil textures may affect crop growth and yield because of soil N availability, soil N leaching, and plant N uptake. The objective of this study was to evaluate effects of three different soils (sandy loam, loam, and clay loam) on cucumber (Cucumis sativus L.) yield, nitrogen (N) use efficiency (NUE), and water use efficiency (WUE) by subsurface drip fertigation in the greenhouse. Three different soil textures are sandy loam, loam, and clay loam with 3 replications. The dimension of each lysimeter was $1.0m(W){\times}1.5m(L){\times}1.0m(H)$. Cucumber was transplanted on April $8^{th}$ and Aug $16^{th}$ in 2011. The subsurface drip line and tensiometer was installed at 30 and 20 cm soil depth, respectively. An irrigation with $100mg\;NL^{-1}$ concentration was automatically applied when the tensiometer reading was 10 kPa. Volumetric soil water content for cucumber cultivation was the highest in 30 cm soil depth regardless of soil texture and was lowered when soil depth was deeper. The volumetric soil water contents at soil depths of 10, 30, 50, and 70 cm were the highest at clay loam, followed by loam, and sandy loam. The growth of cucumber at the $50^{th}$ day after transplanting was the lowest at sandy loam. Cucumber fruit yields were similar for all three soil textures. The highest amount of water use at sandy loam was observed. Nitrogen and water use efficiencies for cucumber were higher for clay loam, followed by loam and sandy loam, while the amount of N leaching was the greatest under sandy loam, followed by loam, and clay loam. Overall, growing cucumber on either loam or clay loam is better than sandy loam if subsurface drip fertigation is used in the greenhouse.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권spc호
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• pp.64-74
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• 2022

The conceptual site model (CSM) is used as a key tool to support decision making in risk based management of contaminated sites. In this work, CSM was applied in Jeonju Industrial Complex where site investigation for groundwater contamination was conducted. Site background information including facility types, physical conditions, contaminants spill history, receptor exposure, and ecological information were collected and cross-checked with tabulated checklist necessary for CSM application. The CSM for contaminants migration utilized DNAPL transport model and narrative CSMs were constructed for source to receptor pathway, ecological exposure route, and contaminants fate and transport in the form of a diagram or flowchart. The component and uncertainty of preliminary CSM were reviewed using the data gap analysis while taking into account the purpose of the survey and the site management stage at the time of the survey. Through this approach, the potential utility of CSM was demonstrated in the site management process, such as assessing site conditions and planning follow-up survey work.

• 한국지반공학회논문집
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• 제22권7호
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• pp.45-54
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• 2006

전기비저항콘은 현장에서 지반의 오염대를 조사하는데 상대적으로 경제적인 비용으로 적용될 수 있다. 그러나, 전기비저항 결과만에 의한 해석은 정량적 데이터베이스의 부족과 함수비 등의 다른 지반공학적 영향인자들에 의해 모호한 결과를 나타낼 수 있다. 본 연구에서는 지반오염조사에서의 전기비저항 측정기법을 보완하기 위하여 정전용량 측정기법을 도입하여 중금속과 유류로 오염된 지반에서의 적용성을 평가하고자 하였다. 함수비와 오염물질의 종류에 따른 전기비저항과 정전용량의 변화를 평가하기 위하여 실내모형시험을 수행하였으며, 그 결과 전기비저항과 유전상수를 통시에 측정하여 분석함으로써 오염대의 감지에 신뢰도를 높일 수 있는 것으로 나타났다. 전기비저항과 정전용량 측정기법은 중금속으로 오염된 포화지반과 지하수대 상부에 존재하는 디젤유 오염층을 감지하는 데 적용성이 높은 것으로 나타났다.

• 자원환경지질
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• 제56권5호
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• pp.501-514
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• 2023

산불은 연소 과정에서 다양한 오염물질을 배출하여 심각한 환경 문제를 초래할 수 있다. 최근 지구 온난화와 기후변화의 영향으로 전 세계적으로 산불의 규모와 빈도가 증가하여 환경에 미치는 영향 역시 급증할 것으로 예상된다. 한국은 산불 발생이 빈번한 동해안 지역에 원자력 발전소가 위치하고 있어, 중대 사고에 대비하여 산불 환경에서 방사성 핵종의 거동 특성에 대한 이해가 요구된다. 본 리뷰 논문에서는 산불이 지하수 토양 환경에 가져오는 변화와 오염 특성을 검토하고, 산불로 변화된 지하수 토양 환경에서의 방사성 핵종 거동을 고찰하였다. 특히, 변화된 지중환경의 여러 특성 중 방사성 핵종의 거동에 영향을 미칠 수 있는 요인들을 고려하였으며, 보다 구체적인 메커니즘 이해를 위해 산불이 초래하는 지하수 토양 환경 변화와 오염에 대한 연구의 필요성을 기술하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.543-550
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• 1999

Hazardous substances produced from industrial sectors have caused serious contamination of soils and groundwater. The hydrophobic organic compounds in the subsurface are hard to be decomposed, and as they soil on the soil or last as a NAPL they might contaminate the groundwater for a long time. Although we recognize the danger of contaminated subsurface, very little was known about the effective remediation technique. This paper focuses on the remediation of the p-Cresol which contaminated subsurface by applying the surfactant-enhanced description technique. Sorption characteristics of soils and organic compounds are studied, and the applications of surfactant solution are studied for effective rededication. The results from this study could be used as some data for surfactant-enhanced rededication. The flexible-wall permeameter tests are performed in which in-situ remediation is simulated. Results show that triton X-100 at 2% solution disrobes p-Cresol 1.7 times as much as water description in the flexible-wall permeameter tests.

• Tribology and Lubricants
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• 제20권5호
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• pp.252-258
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• 2004

In this study, using high cycle fatigue (HCF) criteria, the simulation of rolling contact fatigue is conducted under elliptical contact. The HCF criteria fall into three categories: the critical plane approach, the stress invariant approach and the approach based on the mesoscopic scale. The accurate calculation of contact stresses and subsurface stresses is essential to the prediction of crack initiation life. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions and the subsurface stress field is obtained using rectangular patch solutions. The simulation results show that the critical load is decreasing rapidly and the site of crack initiation also moves rapidly to the surface from the subsurface when the friction coefficient exceeds a specific value for all of three fatigue criteria.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.331-337
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• 2000

A numerical procedure for contact analysis and calculating subsurface stress was developed. The procedure takes the advantage of signal processing technique in frequency domain to achieve shorter computing time. Boussinesq's equation was adopted as a response function in contact analysis. The validity of this procedure was proved by comparing the numerical results with the exact solutions. The fastness of this procedure was also compared with other algorithm.

• 자원환경지질
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• 제27권3호
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• pp.313-321
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• 1994

Structural interpretation by using subsurface attitude of coal seam and outcrop patterns of folds and faults shows that wrench and thrust tectonics took place simultaneously in the study area. From the interference patterns of fold axes, three generations of folding are suggested: $F_1$ (NE-SW), $F_2$ (N-S), and $F_3$ (E-W). Differential displacement of rock mass from north to south yields to E-W fold and Osypcheon Fault. Geometry of subsurface coal seam show different patterns comparing to those of surface outcrop because of shallow-depth crustal shortening which took place post Cretaceous.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.66-69
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• 2001

A subsurface containment system which is constructed by pumping a gelling liquid (Colloidal Silica) into the unsaturated medium is investigated by developing a mathematical model and conducting numerical simulations. The proposed model is verified by comparing experimentally and numerically determined hydraulic conductivities of gel-treated soil columns at different Colloidal Silica (CS) injection volumes. The numerical experiments indicate that an impermeable gel layer is formed within the time period twice the gel-point. At the Same normalized time, the CS solutions with lower NaCl concentrations result ill further migration and poor Performance in plugging the pore space.