• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.454-454
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• 2017

국내 상수도가 보급되지 않은 지역 내 취약 계층은 약 214만 명으로 대부분은 노후관정 및 미신고 관정에서 지하수를 먹는물로 이용하고 있다. 이들은 대부분 미신고 관정이기 때문에 실태파악이 어렵고 정기적인 수질 검사를 실시하지 않아 수질상태에 대한 안전 대책이 미흡한 실정이다. 우리나라의 경우 농촌지역의 관정은 천부지하수의 의존도가 크고 강우에 의한 지표오염물질(축산분뇨, 비료 등)이 관정 내부로 유입 가능성이 매우 높다. 기존 연구에서도 천부지하수 관정의 조사 결과, 질산성질소 및 총대장균군에 의한 수질 오염이 심각하다고 보고된다(Chae et al., 2004; Min et al., 2003). 따라서 상수도 미보급지역 지하수 관정의 지하수 수질 현황을 파악하고, 고농도 오염 관정 및 지역의 경우 정밀조사를 통해 오염 원인을 규명해야 한다. 또한 오염 원인에 대한 향후 개선방안 및 대책안을 마련하여 지하수 수질 안정성 확보를 도모할 필요가 있다. 이를 위해 환경부 산하 국립환경과학원에서는 안심지하수 지원 사업을 2012년 "지하수 안심이용 무료 수질검사 시범사업"부터 시작하여 2016년 "상수도 미보급지역 2016년 안심지하수 지원사업 연구"로 이어지며 수행하였다. 이 사업은 수질분석, 관정내부 탐사, 마을 공용 음용관정 설치지원, 고농도 오염지역 중 시범사업 지역 선정, 고농도 오염지역 수질개선 시범사업으로 구성된다. 수질 분석은 2012년 TA군 내 8개 읍 면의 1,200개 관정, 2013년 경기 북동부권 8개 시 군 11,861개 관정, 2014년 전국 14,494개 관정, 2015년 전국 25,900 관정, 2016년 전국 25,914 관정에 대해 수질 분석을 실시하였다. 수질분석 결과를 바탕으로 고농도 오염지역의 지하수 관정 내부 탐사를 실시하여 소유주에게 주변 환경 개선 조치 및 대민 지원(마을 공용 음용관정 설치)을 수행하고, 시범조사 대상지역을 선정하여 오염지역의 오염원 현황, 수질조사, 지하수 유동 모델링을 실시하여 오염 원인을 파악하였다. 추가로 2014년에는 안심지하수 수질보전 연구로드맵을 작성하여 환경부에 제시하였고, 2015년은 수질개선 사업에 대한 경제성 분석, 수질자료 DB 구축이 완료되었다.

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.151-161
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• 2007

EPS provides a superb self-sufficient stability. Studies on the process of EPS construction method focus on the inchoate phase of general construction, which is increasingly applied to construction sites throughout the world. Unfortunately, there has been little study on the durability and long-term soil behavior involving EPS materials. In this study, the boring, in-site and laboratory tests were conducted to examine the long-term soil behavior in the back-filling of alternating behind the side to which EPS was applied. And results of finite element analysis considering various test results and the soil behavior data measured during the construction show that EPS construction method is a superb process that relieves the load and consequently reduces the settlement, alleviates the stress on the abutment, and prevents lateral flow.

• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.2
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• pp.107-116
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• 2017

When drilling operation is being performed, many physical and chemical changes are occurred near wellbore. To handle various changes of well condition and keep drilling process safe, additives of bulk, such as bentonite for increasing density of drilling mud, barite for increasing viscosity of drilling mud, polymer for chemical control, or surfactant, are added into drilling mud through a mud shear mixer. Because the achievement of the required material property through mud mixing system is essential to stabilize drilling system, it is of importance to analyze multi-phase flow during mud mixing process, which is directly related to increase mixing performance of the system and guarantee the safety of the whole drilling system. In this study, a series of liquid-solid flow simulation based on a computational fluid dynamics (CFD) are performed with comparing to solid concentration in experiment by Gilles et al. [2004] to understand the characteristics of liquid-solid mixing in a mud shear mixer. And then, the simulation-based design of shear mixer are carried out to improve mixing performance in a mud handling system.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.3
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• pp.35-47
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• 1996

A surface panel method treating a boundary-value problem of the Dirichlet type is presented to design a three dimensional body with free surface corresponding to a prescribed pressure distribution. An integral equation is derived from Green's theorem, giving a relation between total potential of known strength and the unknown local flux. Upon discretization, a system of linear simultaneous equations is formed including free surface boundary condition and is solved for an assumed geometry. The pseudo local flux, present due to the incorrect positioning of the assumed geometry, plays a role f the geometry corrector, with which the new geometry is computed for the next iteration. Sample designs for submerged spheroids and Wigley hull and carried out to demonstrate the stable convergence, the effectiveness and the robustness of the method. For the calculation of the wave resistance, normal dipoles and Rankine sources are distributed on the body surface and Rankine sources on the free surface. The free surface boundary condition is linearized with respect to the oncoming flow. Four-points upwind finite difference scheme is used to compute the free surface boundary condition. A hyperboloidal panel is adopted to represent the hull surface, which can compensate the defects of the low-order panel method. The design of a 5500TEU container carrier is performed with respect to reduction of the wave resistance. To reduce the wave resistance, calculated pressure on the hull surface is modified to have the lower fluctuation, and is applied as a Dirichlet type dynamic boundary condition on the hull surface. The designed hull form is verified to have the lower wave resistance than the initial one not only by computation but by experiment.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.5-5
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• 2000

액체 추진 로켓 엔진의 고주파 연소 불안정 관련 이론은 대체로 연소기 내부의 음향 공명 모드와 분무 연소 과정의 상호 작용을 구동 메커니즘으로 전제하며 Rayleigh Criterion의 재해석에 기초하여 불안정성 평가를 위한 매개변수를 도입하고 연소 불안정성을 예측한다. 여기에는 음향장 분석 이론, 음향 불안정 이론, 연소응답 및 기화반응 이론 등이 포함된다. 본 연구에서는 LOX/RPl 추진제 조합의 액체 추진 로켓 엔진 연소기를 대상으로 다차원 순수 음향장 해석과 연소-음향장 분석을 통해 대상 엔진의 고주파 연소 불안정 특성을 예측하였다. 수동 제어 기기인 음향공 설치에 따른 연소기의 음향장 및 연소-음향장의 특성 변화를 고찰하고 위 결과를 종합하여 음향공의 연소 불안정 억제 성능 및 대상 엔진의 연소 불안정성을 평가하였다. 연소기 형상 및 음향공 설치에 따른 다차원 순수 음향장 해석은 상용코드인 ANSYS를 사용하여 수행하였다. 내부 유체는 압축성, 비점성 유체로 유체의 평균 유동은 무시하며 위치에 관계없이 균일한 물성치를 부여하였다. 정상상태 연소과정을 가정하고 평형 화학을 이용한 분석 결과로부터 연소 기체의 관련 물성치를 결정하였다. 연소기 길이 방향, 반경 방향, 원주 방향 격자점들의 음향 특성을 주파수 영역에 대해 해석하고 3차원 음향 모드 형상을 토대로 음향장을 분석하였다. 연소-음향장 해석은 음향 불안정 이론 중 n- $\tau$ 2 매개변수 기법을 사용하였다. 연료 액적의 분무 연소 과정을 1차원적으로 가정하고 정상상태의 평형 화학 계산 결과를 이용하여 엔진의 연소면을 1차원적으로 설정하였다. 상류 연소응답과 중립 안정 곡선을 토대로 대상 엔진의 연소 불안정 특성을 분석하였다.구 분석 결과 기술적 문제점으로는 배기 가스온도가 낮은데 따른 출구 부분의 Bearing, Sealing이 문제가 될 수 있다고 판단되며 배기 가스 자체에 대기 공기중에 함유되어 있던 습기가 얼어붙는(Icing화) 문제가 발생하기 때문에 배기가스의 Icing을 방지하기 위하여 압축기 끝단에서 공기를 추출하여 배기부분에 송출할 필요성이 있는 것으로 판단되었다. 출구가스의 기체 유동속도가 매우 빠르므로 (100-l10m.sec) 이를 완화하기 위한 디퓨저의 설계가 요구된다고 판단된다. 또 연소기 후방에 물을 주입하는 경우 열교환기 및 기타 부분품에 발생할 수 있는 부식 및 열교환 효율 저하도 간과할 수 없는 문제로 파악되었다. 이러한 기술적 문제가 적절히 해결되는 경우 비활성 가스 제너레이터는 민수용으로는 대형 빌딩, 산림, 유조선 등의 화재에 매우 적절히 사용되어 질 수 있을 뿐 아니라 군사적으로도 군사작전 중 및 공군 기지의 화재 그리고 지하벙커에 설치되어 있는 고급 첨단 군사 장비 등의 화재 뿐 아니라 대간첩작전 등에 효과적으로 활용될 수 있을 것으로 판단된다.가 작으며, 본 연소관에 충전된 RDX/AP계 추진제의 경우 추진제의 습기투과에 의한 추진제 물성 변화는 미미한 것으로 나타났다.의 향상으로, 음성개선에 효과적이라고 사료되었으며, 이 방법이 편측 성대마비 환자의 효과적인 음성개선의 치료방법의 하나로 응용될 수 있으리라 생각된다..7%), 혈액투석, 식도부분절제술 및 위루술·위회장문합술을 시행한 경우가 각 1례(2.9%)씩이었다. 13) 심각한 합병증은 9례(26.5%)에서 보였는데 그중 식도협착증이 6례(17.6%), 급성신부전증 1례(2.9%), 종격동기흉과 폐염이 병발한 경우와 폐염이 각 1례(2.9%)였다. 14)

• Tunnel and Underground Space
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• v.16 no.4 s.63
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• pp.281-287
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• 2006

Intake of groundwater by tunneling in a mountainous area mostly results from groundwater flow through fractured parts of total rock mass. For reasonable analysis of this phenomenon the representative joint groups 1, 2, and 3 have been selected by previous investigations, geological/geophysical field tests and boring works. Three dimensional fractures were generated by the FracMan and MAFIC which is a three dimensional finite element model has been used to analyse a groundwater flow through fractured media. Monte Carlo simulation was applied to reduce the uncertainty of this study. The numerical results showed that the average and deviation of amounts of groundwater intaked into tunnel per unit length were $5.40{\times}10^{-1}$ and $3.04{\times}10^{-1}m^3/min/km$. It is concluded that tunnel would be stable on impact of groundwater environment by tunneling because of the lower value than $2.00{\sim}3.00m^3/min/km$ as previous and present standard on the application of tunnel construction.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.121-126
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• 2010

Current technology for radioactive waste disposal facility is operated as part of KURT site characterization in terms of reliability assessment is conducted to expand. In this study, a geological model of KURT surrounding area on the basis of flow characteristics of the site-scale hydrogeological study was about. Distributed in the study area into four boreholes were plotted using the stereo net NS, NW, EW, Low-angle fracture group was able to identify the components of geological models and include top soil layer, belt of weathering, Low-angle fracture zone, fracture zone was divided into. Separated by fracture of the hydraulic test of through the groundwater aquifer that provides the flow hydraulic conductivity and insulation hydraulic affecting the slope of the normal distribution for the size and direction by performing statistical analysis of fracture in the direction of local ns The advantage was confirmed. In addition, Low-angle fracture hydraulic conductivity of the value of 3.61e-07 m/s has a value greater than the major fracture, the fracture zones exist in the base rock and base rock and the hydraulic characteristics of the different methods applied and had to have a different interpretation judged by was.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.318-328
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• 2018

The purpose of this study was to investigate the differences in the characteristics of the aesthetic salon operation and job satisfaction according to important considerations in opening aesthetic salons as well as to provide basic data for improving the operation of the salons. Toward this aim, a questionnaire survey was conducted for owners of small aesthetic salons across South Korea from January-March, 2016. Results were as follows: Among those who identified means of transportation and parking convenience as key considerations in launching aesthetic salon businesses, length of service, length of business operation, monthly fixed revenue and proportion of the highest profit were highest. Job satisfaction (F=3.223, p<.05) was highest (M=4.11) among those that responded 'floating population' as a primary component in launching aesthetic salon businesses, and lowest among owners who mentioned 'cost of investment' (M=3.41). Specifically, job mobility (F=2.960, p<.05) was the highest among respondents who selected means of transportation and parking convenience (M=3.95) as key criteria in launching aesthetic salon business. For the stable operation of an aesthetic salon, a location with high floating population, good transportation, parking convenience, high levels of customer access, and job satisfaction are critical factors. In addition, future studies should examine marketing strategies by operating characteristics.

• 한국지구물리탐사학회:학술대회논문집
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• 2000.09a
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• pp.19-40
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• 2000

We applied both SP monitoring and pole-pole array resistivity surveys and SP survey and dipole-dipole array resistivity survey to leakage problems in several embankments and dike, respectively, to estimate and detect the zone of leakage. The embankment is generally affected by tidal variation and has low resistivity characteristics due to the high saturation of seawater. According to this situation, SP monitoring and resistivity survey using pole-pole electrode array, which is relatively more effective to the conductive media, were carried out to delineate the leakage zones of sea water through the embankment. We checked out electrical conductivity(EC) and temperature variations along the inner part of the embankment to detect the zone of seawater leakage and found that the measured EC value agreed to that of seawater in the leakage zone and the temperature was lower than that of the vicinity of leakage zone. SP monitoring results were coincide with tidal variations at each embankment. Based on the survey results, it is concluded that both SP monitoring and the pole-pole array resistivity method are quite effective for investigation of seawater leakage zones in the embankment.

• Journal of Energy Engineering
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• v.24 no.1
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• pp.149-163
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• 2015

In this study, we conducted study on the confirmation of thermal-hydraulic safety for Mast assembly with Computational Fluid Dynamics(CFD) analysis. Before performing the natural convection analysis for the Mast assembly by using CFD code, we validated the CFD code against two benchmark natural convection data for the evaluation of turbulence models and confirmation of its applicability to the natural convection flow. From the first benchmark test which was performed by Betts et al. in the simple rectangular channel, we selected standard k-omega turbulence model for natural convection. And then, calculation performance of CFD code was also investigated in the sub-channel of rod bundle by comparing with PNL(Pacific Northwest Laboratory) experimental data and prediction results by MATRA and Fluent 12.0 which were performed by Kwon et al.. Finally, we performed main natural convection analysis for fuel assembly inside the Mast assembly by using validated turbulence model. From the calculation, we observed stable natural circulation flow between the mast assembly and pool side and evaluated the thermal-hydraulic safety by calculating the departure from nucleate boiling ratio.