• 터널과지하공간
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• 제19권4호
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• pp.339-347
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• 2009

터널굴착기술이 발달된 근래에도 터널붕괴사고는 지속되고 있다. 본 논문은 미고결 지반에서 발생하는 대표적인 두 가지 사례를 제시하였다. 각각의 사례에 대한 터널붕괴원인을 계측기록과 수치해석 모델링을 통해 분석하고 붕괴메커니즘을 고찰하였다. 이로부터 미고결 지반에서 터널붕괴의 핵심 지시자는 전단변형율과 지하수위의 변화이며, 터널붕괴는 굴착과정에 따라 터널주변의 전단변형이 어떠한 양상으로 발전되느냐와 밀접히 관련되어 있음을 알 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.660-670
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• 2009

Neighboring construction becomes mainstream of Ground excavation in downtown area. This causes the displacement, deformation, stress condition, etc of the ground surroundings. Therefore Neighboring construction have an effect on Neighboring structure. All these years a lot of Neighboring construction carried out, and the accumulation of technology also get accomplished. But earth retaining structure collapse happens yet. Types of earth retaining structure collapse are 12. 1. Failure of anchor or strut system, 2. Insufficiency of penetration, 3. H-pile Failure on excessive bending moment, 4. Slope sliding failure, 5. Excessive settlement of the back, 6. Deflection of H-pile, 7. Joint failure of coupled H-pile, 8. Rock failure when H-pile penetration is rock mass, 9. Plane arrangement of support systems are mechanically weak, 10. Boiling, 11. Heaving, 12. Over excavation. But field collapses are difficult for classification according to the type, because collapse process are complex with various types. When we consider the 12 collapse field, insufficient recognition of ground condition is 4 case. Thorough construction management prevents from fault construction. For limitations of soil survey, It is difficult to estimate ground condition exactly. Therefore, it should estimate the safety of earth retaining system, plan for necessary reinforcement, according to measurement and observation continuously.

• Bulletin of the Korean Chemical Society
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• 제21권6호
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• pp.583-587
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• 2000

Depletion kinetics of ground state FeO molecules by $0_2$, $N_2O$ and $N_2$ has been studied at room temperature. The ground state FeO molecules were generated by photolysis of a $Fe$(CO)_5$/M(O_2$, $N_2O)/He$ mixture using an unfocused weak UV laser beam. The formation of ground state FeO molecules was identified by a laser-induced fluorescence (LIF) method. The intensity distribution of those undisturbed rotational lines suggests that the rotational temperature of the ground state FeO molecules is lower than room temperature. The LIF intensities of FeO molecules at different partial pressures of $0_2$, $N_2O$ and $N_2$ were monitored as a function of the time delay between the photolysis and probe laser pulses to obtain the depletion rate constants for the ground state FeO. They were 1.7+ 0.2x $10^{-12}$, 4.8 $\pm0.4$ x $10^{-12}$, and $1.4\pm$ 0.2x $10^{-12}cm^3$molecule^{-1}s^{-1}$$ by $0_2$, $N_20$, and $N_2$, respectively.

• 대한전자공학회논문지TC
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• 제48권10호
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• pp.13-19
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• 2011

이 논문은 위성항법시스템을 이용한 위치측위에서 지역별 특성에 따른 위치오차실험을 통하여, 음영지역 발생 원인과 해결 방법을 제안하기 위한 연구이다. 동적측위에서 이동체는 이동 위치에 따라 사용할 수 있는 위성항법시스템의 수가 변화한다. 정확한 위치측위를 위해서는 4개 이상의 위성항법시스템으로부터 위치정보데이터를 수신 받아야 한다. 하지만 급격한 산업화와 열악한 지역 환경으로 위치오차가 커지고 음영지역이 발생한다. 이러한 위치오차를 줄이고 음영지역 발생을 해소하기 위해서는 대도시의 환경과 지역 환경 특성에 따른 원인을 파악하는 것이 중요하다. 따라서 본 논문에서는 대도시, 주택 지역, 숲 지역, 바다 지역, 대지 등을 선정하여 위치오차와 음영지역 발생 원인을 실험하였다. 그리고 이 논문을 기반으로 지역 환경에 따른 적합한 고정밀 측위 알고리즘을 제안하고, 음영지역해소 알고리즘을 제안하려고 한다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권7호
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• pp.137-144
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• 2019

근단층 지역에 위치한 교량은 근단층지반운동에 대한 내진안전성을 확보하는 것이 중요하다. 본 연구에서는 연약지반이 두껍고 다양한 지층으로 구성된 지역에 건설되는 단일형 현장타설말뚝 교량의 지진거동특성과 내진안전성을 분석하였다. 근단층지반운동을 생성하고 지반해석을 수행하여 각 지층에서의 지반가속도이력을 산정하였다. 이 가속도이력을 이용하여 각 지층의 지반을 등가스프링으로 모델화하고, 각 지층에서의 가속도시간이력을 입력지반운동으로 하는 다지점 가진 지진해석을 수행하였다. 근단층지반운동의 특성으로 인하여 교량은 탄성영역 내에서 거동하였지만 최대모멘트의 발생 위치 등이 설계지반운동을 고려할 때와는 상이한 특성을 보였다.

• Earthquakes and Structures
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• 제9권2호
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• pp.431-453
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• 2015

A destructive earthquake, the magnitude of this earthquake was 7.2, hit Van, Turkey on October 23, 2011. After this devastating earthquake, a moderate earthquake which had 5.7 magnitude on November 9, 2011 occurred in Edremit, Van. These earthquakes caused heavy damages and collapses in many reinforced concrete buildings with loss of lives. In this paper, characteristics of ground motions of these earthquakes were studied and, deficiencies in structural elements and engineering faults such as poor workmanship and quality of construction, soft and weak stories, strong beam-weak column, short column, large overhang, hammering and unconfined gable wall were investigated. According to the observations, it was seen that, low quality of structural materials, lack of engineering services, inappropriate design and construction with insufficient detailing of the structural elements were the main reasons of heavy damages.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.2043-2045
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• 2004

This thesis complemented the weak points that the existing theses did not represented a phase characteristic as the equivalent circuit by applying 4-port simulation to DGS (Defected Ground Structure) characteristic and an equivalent circuit, which are the transmission line structure that has the defect made in the ground surface. We used a distribute device and a lumped device, obtained the equivalent circuit by applying the structure of balun to a discontinuous part. An indicated DGS (Defected Ground structure) is a dumbbells-shaped single defect, we indicated satisfying a magnitude and phase characteristics by applying this equivalent circuit.

• Structural Engineering and Mechanics
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• 제39권6호
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• pp.877-893
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• 2011

Response spectra of earthquake ground motions are important in the earthquake-resistant design and reliability analysis of structures. The formulation of the response spectrum in the frequency domain efficiently computes and evaluates the stochastic response spectrum. The frequency information of the excitation can be described using different functional forms. The shapes of the calculated response spectra of the excitation show strong magnitude and site dependency, but weak distance dependency. In this paper, to compare the effect of the earthquake ground motion variables, the contribution of these sources of variability to the response spectrum's uncertainty is calculated by using a stochastic analysis. The analytical results show that earthquake source factors and soil condition variables are the main sources of uncertainty in the response spectra, while path variables, such as distance, anelastic attenuation and upper crust attenuation, have relatively little effect. The presented formulation of dynamic structural response in frequency domain based only on the frequency information of the excitation can provide an important basis for the structural analysis in some location that lacks strong motion records.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.119-121
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• 2008

In underground power cable system, the device for limiting over-voltage is needed when transient over-voltage break out between sheath and ground. For this reason, the SVL(Sheath Voltage Limiter) has been applied on weak points. But the broken SVLs which are installed on the single point bonding system on underground cable are frequently found. In this paper, EMTP(Electromagnetic Transient Program) is utilized to analyze effects on the installation methodology of the parallel ground conductor and SVL for the single point bonding system on the underground cable. The result shows that the proposed installation methodology can be applied for single point bonding system and contribute for power system stabilization.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2004년도 하계학술대회
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• pp.386-389
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• 2004

This thesis complemented the weak points that the existing theses did not represented a phase characteristic as the equivalent circuit by applying 4-port simulation to DGS (Defected Ground Structure) characteristic and an equivalent circuit, which are the transmission line structure that has the defect made in the ground surface. We used a distribute device and a lumped device, obtained the equivalent circuit by applying the structure of balun to a discontinuous part. An indicated DGS (Defected Ground structure) is a dumbbells-shaped single defect, we indicated satisfying a magnitude and phase characteristics by applying this equivalent circuit.