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소규모 지하굴착에서 지중경사계와 변형률계의 최적 위치 선정에 대한 연구
강기천,박진욱,노병진,손가호,윤성규 한국지반신소재학회 2023 한국지반신소재학회 논문집 Vol.22 No.2
Currently, there are cases in Korea where economic damage has occurred due to the ambiguity instrument installation and operation standards in the construction of temporary earth retaining wall, failing to prevent collapse of temporary earth retaining wall at the construction site in advance. Therefore, in this study, a numerical analysis was conducted to find the appropriate installation location of the inclinometer and strain gauge among the installed instruments shown in the design drawing of the temporary earth retaining wall. As a results, It was found that the installation position of the underground inclinometer is the corner of the retaining wall in the case of plane-deformation analysis, and the most displacement occurs in the center of the excavation surface in the case of 3D analysis. When the stress and moment are comprehensively analyzed, the corner is judged to be a vulnerable point. In the case of the strain gauge, In plane-deformation analysis and 3D analysis, the maximum bending stress occurred at the wale connection where the end of the strut and the counter strut are in contact. At this point, it is analyzed that it is necessary to focus on installing and managing the connection to prevent accidents from being vulnerable. 현재 국내에서는 흙막이 가시설 공사에서 계측기 설치 및 운영기준이 모호하여 공사현장에서 흙막이 공사의 붕괴사고를 사전에 예방하지 못하여 경제적 피해가 발생한 사례가 있다. 따라서 본 연구에서는 흙막이 가시설 설계도면에 제시되어 있는계측기 중 지중경사계 및 변형률계의 적합한 설치 위치를 찾고자 수치해석을 통한 연구를 진행하였다. 해석결과 지중경사계의설치 위치는, 평면변형 해석의 경우 가시설의 우각부에서, 3차원 해석의 경우는 굴착면의 중심부에서 가장 많은 변위가 일어나는 것으로 나타났다. 지반응력과 모멘트를 종합적으로 분석하였을 때 우각부가 취약지점으로 판단된다. 변형률계의 경우 평면변형 해석과 3차원 해석에서 버팀대 끝단과 맞버팀대가 접하는 띠장 접속부에서 최대 휨 응력이 발생하였다. 이 지점에서취약 부분으로 사고예방을 위해서는 접속부에 중점적 설치 및 관리가 필요한 것으로 분석된다.
강기천 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.4
We investigate the local geometric phase induced by Faraday’s law of induction in a superconductingcharge qubit threaded by an Aharonov-Bohm flux. A quantum-state reconstruction scheme,which is based on measurement of three complementary quantities, that is, the extra charge and twolocal currents, is introduced. We find that, while the variation of the local phase with magnetic fieldis determined by Faraday’s law, incorporation of the time-reversal symmetry enables complete determinationof the local phase. This procedure clearly demonstrates that the local geometric phaseis a physical quantity (aside from a global phase factor), in contrast to the standard description ofthe Aharonov-Bohm effect.
Complementarity in a Closed-Loop Aharonov-Bohm Interferometer
강기천,장동인,이후종,정윤철 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6
We study complementarity in a two-terminal closed-loop Aharonov-Bohm interferometer with a quantum dot embedded in an arm of the ring and a nearby charge detector capacitively coupled to the quantum dot. We show that perfect charge detection does not give full information of the electronic path, so it does not completely suppress the interference. We propose that this property can be verified even in the limit of weak charge detection by investigating the dephasing of the first and the second harmonics of the Aharonov-Bohm oscillation. The first harmonic of the AB oscillation is reduced monotonically as a function of the charge detection strength. In contrast, the second harmonic interference remains unaffected due to the fact that charge detection is not able to detect the electronic path responsible for the second harmonic. Our theory confirms that the particle-like behavior of an electron emerges from the path information itself rather than from the disturbance.
강기천 한국무역연구원 2015 무역연구 Vol.11 No.3
Does FTA increase the spread of exports to neighboring countries outside the FTA area? An analysis of the development of exportation from Korea to Latin American countries after the inception of the Korea-Chile FTA in April 2004 provided evidence to support this hypothesis. Thus, this paper analyzed the relationship between the Korea-Chile FTA and the growth of Korean exports to Latin American countries. The results showed that the Korea-Chile FTA is one of the reasons behind the noticeable increase of Korean exports to Latin American countries.
The Choice of Export Destinations and Its Determinants: Evidence from Korean Exports
강기천 한국경제학회 2013 The Korean Economic Review Vol.29 No.1
Empirical evidence shows that zeros in a bilateral export matrix are very common and non-zeros are extremely concentrated across destinations. According to the simple version of Melitz (2003) model, variations in market size, as well as variable and fixed trade costs across destinations are potential candidates for explaining the stylized facts on the incidence of zeros and non-zeros in a trade matrix. Using Korean disaggregate export data (HS 10-digit level), this paper finds that export participation depends on destination-specific factors such as destination income, distance, local distribution cost, and fixed entry costs associated with the destination language, institution, and information. In line with this theory, the empirical findings suggest that destination-specific factors are important for shaping the country’s export entries.
China’s Impact on Korean Import Price Level
강기천 한국동북아경제학회 2016 동북아경제연구 Vol.28 No.4
Many people have believed that China’s export growth has led to downward pressure on the import prices in the world countries. However, empirical findings have documented that the impact of China was clearly deflationary, but the effect was quite small. The impact of China on import price may be large in small open countries like Korea. The startling increase in the number of Chinese goods may provide a possibility that the spectacular growth in import from China was largely attributed to new goods (extensive margin), and then the large growth of Chinese goods reduced the cost of living for Korean consumers. In order to identify the impact of new goods on the cost of living, we adopt the methodology of Broda and Weinstein(2006, 2010), This paper empirically quantifies the impact of new Chinese goods on the Korean import price. The paper finds that the upward bias in the conventional import price index aggregated over Chinese goods is approximated 31 percent between 1992 and 2008, or 1.93 percent per year. The increase in new Chinese goods has resulted in substantial deflationary pressure on Korean import prices. We confirm the truth of the conjecture that China’s impact on a small open economy like Korea may be significant.
ON THE MEASURMENT OF EXPORT VARIETY: EVIDENCE FROM KOREA AND TAIWAN
강기천 한국경제학회 2006 The Korean Economic Review Vol.22 No.2
This paper sheds some light on measure of export variety and features the geographical spread of a country’s export varieties to the worldwide countries. First this paper constructs measures of export variety that are consistent with an underlying constant-elasticity of substitution (CES) aggregator function to compare export varieties from a country to its many destination countries. Second this paper shows how exports to different destination markets shows a distinct pattern with greatest variety to the wealthier and larger markets, following by exports of those products to other countries.