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Comparative Analysis of the Vulnerable Period of Groundwater Level Drawdown
이재범,양정석 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.11
This study selected groundwater level as the factor to represent the changes in groundwater resources and developed an evaluation method for the management of monthly groundwater level considering the temporal variability with the target of 9 sub-basins located in the Namwon. For the evaluation of vulnerable period in the groundwater level considering the influence of rainfall on the underground aquifer, the following methods were used: applying effective rainfall amount based on the application of rainfall data, and using rainfall data with the notion of critical infiltration, among which vulnerable periods were compared for evaluations. A standard was developed for evaluating groundwater level; the weighting values were determined by using the entropy method, and the vulnerability period of groundwater resources of each sub-basin was evaluated via multiple decision-making methods. The methods developed in this study are expected to make grounds for building measures for the effective spatiotemporal management of groundwater resources.
이재범,이영주,심성한,조수진 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.8
Concrete gravity dams are widely constructed owing to their advantages of low maintenance cost and relatively low risk of sudden failure. However, the structural failure rate has been reported to be higher than other dam types. Although various studies have been conducted to assess the structural fragility of concrete gravity dams, not enough emphasis was placed on system-level fragility and sensitivity analyses, which provide crucial information for mitigating dam failure. This study proposes a new probabilistic framework for system fragility and sensitivity analysis by employing a finite element model for concrete gravity dams. The proposed framework consists of four steps, namely, structural analysis modeling considering the realistic loading conditions, component fragility analysis employing finite element reliability analysis, system fragility analysis employing system reliability analysis, and system sensitivity analysis using the finite difference method, which require several numerical algorithms and computational techniques. The proposed framework is applied to a numerical example of a typical concrete gravity dam in South Korea, and the analysis is completed successfully. As a result, the example dam is found to be relatively more vulnerable to sliding and concrete overstress than ground overstress. In addition, it is revealed that the dam system is more likely to fail in the overflow part than in the non-overflow part. The most critical factor in preventing these failures is the concrete mass density, followed by the silt mass density and the concrete compressive strength. Based on these analysis results, it is confirmed that the proposed framework provides valuable information for risk-informed structural design and failure mitigation of concrete gravity dams.
GaOOH 선구체의 스핀코팅에 의한 GaN 박막의 성장
이재범,김선태,Lee, Jae-Bum,Kim, Seon-Tai 한국재료학회 2007 한국재료학회지 Vol.17 No.1
GaN thin fan were grown by spin coated colloidal GaOOH precursor. Polycrystalline GaNs with crystalline size of $10{\sim}100nm$ were grown on $SiO_2$ substrate. The shape of crystallite above $900^{\circ}C$ had the hexagonal plate and column type. X-ray diffraction patterns for them correspond to those of the hexagonal wurtzite GaN. With increasing droplets. i.e, thickness of deposited layers, XRD intensity increased. PL (photoluminescence) spectrum consisted with an weak near band-edge emission at 3.45 eV and a broad donor-acceptor emission band at 3.32 eV. From the low temperature PL measurement on GaN grown at $800^{\circ}C$ that the shallow donor-acceptor recombination induced emission was more intense than the near band-edge excitonic emission.
Values of Health Qigong as Elderly Exercise
이재범,이동준 한국발육발달학회 2015 한국발육발달학회지 Vol.23 No.1
Recently, interest in Health Qigong training in the East has been increasing and people pay more attention tothe enhancement of national health by supplementing worldly proven western medicine with traditional medicine of theirown countries. From this aspect, Health Qigong has attracted people’s attention which is a traditional exercise and healthenhancement sports in the East. Health Qigong is a traditional training method as well as exercise to coordinate and enforcevarious organs and systems of human bodies through posture coordination, breath training, relaxation of body and mind andrhythmical movements which has theoretical base in oriental medicine and does not ask extreme movements. Ageing of thepopulation makes big influence on life of individuals and families as well as causing national and social problems. In themodern society which is being changed dynamically, Health Qigong is not only a program enhancing health but also hasvalue and efficacy as a new paradigm in sports of the elderly to reach consistency between mind and body and knowledgeand conduct through training of sprit of mind, meridians, and breathing.