• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.463-470
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• 2000

In tunnel excavation by blast beneath the surface structures in urban area, the characteristics of ground vibration induced by blast and its influence on surface structures are analyzed by the field test and the numerical analysis on dynamic behaviors of the structure. According to the field test on the propagating characteristics of blast vibration through the rock mass and the concrete foundation pile. the attenuation index of peak particle velocity with distance shows the range of 1.7∼2.0 for the rock mass and the range of 2.0∼2.3 for the concrete pile. This shows that the blast vibration reduces more rapidly in the concrete pile. It is known from the numerical analysis on dynamic behavior of the structure that the coefficient of response, velocity ratio of structure response to input wave, is different according to the story of the structure. It can be said from this research that the characteristics of the ground vibration and the dynamic behavior of the structure should be well evaluated and be considered as important factors for safe blasting design especially in underground excavation at shallow depth in urban area.

• 대한가정학회지
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• 제44권12호
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• pp.189-201
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• 2006

The purpose of this study was to explore consumers' experiences in one used market site. For this purpose, in-depth interviews were conducted for the 8 consumers who were members of the used market site. In the study methodology, the grounded theory designed by Strauss and Corbin was utilized. From the analysis results, 23 subcategories and 11 categories were created. In the axial coding, the following paradigm model was proposed: 1) the casual conditions were "the pond of information" and "underground market," 2) the contextual conditions were "inconsistent behavior" and "error of communication", 3) the central phenomenon was "non-ethic behavior of seller/buyer, 4) the intervening conditions were "induction of intimacy", "use of patronage", and "creation of network", 5) the action/interaction strategy was "being shrewd", and 6) the consequence was "adaptation/non-adaptation". In selective coding, the core category was "to adapt of non-ethic behaviors through being shrewd." Based on the core category, the following four types of process of adaptation of the used market site were found: "A selfish addict," "An advanced utilitarian", "A hard philosopher," and "A cynical dropout".

• 설비공학논문집
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• 제27권3호
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• pp.169-173
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• 2015

Recently, ground source heat pump (GSHP) systems have attracted much attention, according to the enhanced social demand of renewable energy. GSHP systems can achieve higher coefficient of performance than the conventional air-source heat pump systems by utilizing stable underground temperature. However, the initial cost of GSHP system is higher than that of the conventional systems, especially, in the small-size buildings. Therefore, it is necessary to develop small-size ground heat exchanger with low cost and quick installation. In this study, a unit-type ground heat exchanger was developed and heat exchange rate was calculated by the numerical simulation. As a result, 27.45 W/m of heat exchange rate was acquired in the condition of $0.5m{\times}0.2m{\times}2m$ unit.

• 터널과지하공간
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• 제25권3호
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• pp.244-254
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• 2015

모래와 자갈이 암반 위에 퇴적된 지층에서 터널의 윗부분이 지하수가 많은 모래자갈층을 통과하는 상황에서 터널을 시공하였다. 지상의 일부 곡선구간에 빌딩들도 있는 저심도 터널을 안전하게 시공하기 위하여 강도가 작고 지하수가 많은 터널천정부의 모래자갈이 터널 내로 낙하하는 유사현상(sand flow)을 예방해야 하였다. 이를 위하여 대구경강관다단그라우팅이나 제트그라우팅으로 터널주변 충적층을 굴착 전에 미리 보강한 후 터널을 시공하였다. 이와 같이 터널을 보강한 효과와 지상빌딩의 안전을 시공 중 계측을 통하여 확인하였다.

• 방사성폐기물학회지
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• 제14권1호
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• pp.11-19
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• 2016

This paper focuses on the estimation of durability and service-life of reinforced concrete structures in Wolsong Low- and intermediate-level wastes Disposal Center (WLDC) in Korea. There are six disposal silos located in the saturated environment. The silo concrete is degraded due to reactions with groundwater and chemical attacks, and finally it will lose its properties as a transport barrier. The infiltration of sulfate and magnesium, leaching of potassium hydroxide, and chlorine induced corrosion are the most significant factors for degradation of reinforced concrete structure in underground environment. From the result of evaluation of the degradation time for each factor, the degradation rate of the reinforced concrete due to sulfate and magnesium is $1.308{\times}10^{-3}cm/yr$, and it is estimated to take 48,000 years for full degradation while potassium hydroxide is leached in depth of less than 1.5 cm at 1,000 years after the initiation of degradation. In case of chlorine induced corrosion, it takes 1,648 years to initiate corrosion in the main reinforced bar and 2,288 years to reach the lifetime limit of the structural integrity, and thus it is evaluated as the most significant factor.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.1017-1020
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• 2008

콘크리트구조물에서의 탄산화 현상은 단독 또는 복합적으로 작용하고 사용환경의 조건에 따라 각각 상이한 탄산화 현상을 나타나게 된다. 이에 본 연구에서는 사용연수가 $10{\sim}60$여년이 경과되고 사용환경이 상이한 건축물과 토목구조물에 대하여 탄산화 깊이와 알칼리 농도를 측정하여 열화 정도를 판단하였다. 그 결과 건축물(옥내)은 외기에 노출된 토목구조물 보다 빠르고 해안가에 근접 할수록 열화현상이 심화된 것으로 나타났다. 또한, 공동구 또는 지하터널 보다는 하수암거의 용도로 사용하는 콘크리트구조물에서의 열화현상이 큰 것으로 조사되었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.643-650
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• 2009

The necessary consequence by the rapid economic growth in large-scale urban excavation is increasing. If the site is the congested in downtown, the scale of excavation will get the large-scale and the extreme depth. We have achieved a high level technology internationally by the design and construction of underground excavation since 1980's. But the accidents during excavation are frequently occurring. So, this demage instigates the human life loss as well as economical loss. The recent accident is come about the damage for public facilities such as the railroad, subway and etc. in addition to the loss of life and property. For these reasons, the recent accident is being caused the damage of copious social overhead capital. The reasons of collapse during excavation can be classified roughly into the administrative part(sanction, permission), the investigation and design, the construction and management and etc. In this study the close check for the cases of the recent collapse is performed and the improvement course for the prevention of collapse is found.

• 한국응용곤충학회지
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• 제30권3호
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• pp.174-179
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• 1991

1986~1990년에 3년근 인삼포장에서 참검정풍뎅이 유충에 의한 춘기 피해 양상을 조사한 결과 인삼포장의 바깥쪽일수록 피해가 심하였는데 이는 참검정풍뎅이 자성충의 dirks 이동 습성 때문으로 보인다. 3령 유충에 의한 3년근 인삼의 피해부는 뿌리 동례의 상부, 중부, 하부 또는 뿌리 전체였으며 드물게 지하부 줄게에도 피해가 있었다. 섭식기 3령층의 평균 서식 깊이는 인삼 유묘, 2년근, 3년근, 쑥에서 각각 3.2cn, 5.6cm, 6.6cm, 4.9cm 였다. 춘기의 참검정풍뎅이 유충에 의한 인삼의 피해는 주러 5월 중순에서 7월 상순에 발생하였고 강우량이 증가할 경우 피해가 일시적으로 감소하는 것으로 보였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2017-2022
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• 2008

The crude oil pump system is the equipment for transporting crude oil and it consists of 3 major components, a motor and an impeller which discharge underground crude oil, a pipestack that transmits the cooling oil and power, and a cooling oil unit & junction box that provides cooling oil and electric power. When considering the system characteristics that it has to be installed at a depth of deeper than 100 m, a design technology for the efficient control of the heat occurring at a conductor and motor is necessary and it is the essential factor for ensuring system durability. In this paper, therefore, cooling oil flow has been calculated to satisfy the limit value of the system temperature by analyzing heat flow considering the related losses such as loss of conductor, contact resistor loss at the conductor connection, and operation loss of motor. And the operation temperature has been set up based on the temperature of crude oil and the heat of motor and conductor. Also, a design for cooling of crude oil pump system has been proposed by calculating the operation pressure loss and selecting the capacity of a cooling oil pump and a heat exchanger.

• 한국지반공학회논문집
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• 제33권7호
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• pp.43-53
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• 2017

최근 도시지역에서 빈번하게 발생하는 도로함몰은 지하에 생성된 동공으로 인해 지표면이 붕괴되는 현상을 의미한다. 지하 공간에서 동공 생성 과정과 생성된 동공이 도로함몰로 이어지는 현상을 이해하기 위해서는 동공의 형성 메커니즘을 명확히 이해할 필요가 있다. 따라서 본 연구에서는 실제 사례와 여러 모델 시험 결과를 분석하여 두 가지 가능한 메커니즘을 제시하였으며 각 메커니즘에 대해 개별요소법 기반의 수치해석 시뮬레이션을 수행하였다. 특히, 도로함몰 영향인자 중 토사 유출구의 크기와 지반의 간극비, 지반 구성 입자 형상의 영향을 확인하기 위한 수치해석을 통해 유출구 특성과 지반 조건에 따라 입자 손실과 지표 침하가 다르게 발생할 수 있음을 확인하였다. 또한, 불연속 침하 해석 결과로 본 연구에서 제시한 도표를 통해 동공의 지름과 심도를 통해 지반의 포화 시 거동을 예측할 수 있다.