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New Definition of the Kilogram by Fixing the Numerical Value of the Planck Constant
김동민(Dongmin Kim),김명현(MyeongHyeon Kim),우병칠(Byung-Chill Woo),이광철(Kwang-Cheol Lee) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.4
In the current SI (International System of Units), the kilogram is defined by the mass of a material artefact. In this instance, because the artefact can be damaged during use, the present definition is inherently considered unstable. To overcome the shortcomings of the present kilogram definition, the SI will be redefined in near future. In the new SI, the kilogram will be redefined by fixing the numerical value of the Planck constant. After the kilogram redefinition, realization experiments which link the Planck constant to the mass will be necessary. In the new SI, the kilogram will be realized through experiments including the Kibble balance and the X-ray crystal density. The Kibble balance, which is named for the scientist Bryan P. Kibble, is an electromechanical device comparing mechanical power and electrical power. The electrical power is proportional to the Planck constant, because of the voltage and resistance are measured using the Josephson effect and the quantum Hall effect, respectively. The Planck constant is an invariant and not a characteristic of a man-made object, or a specific experiment. The new mass unit is more stable than the current one, and will pave the way for the advancement of precision measurement.
역간 OD자료를 활용한 급행열차 최적 정차역 결정 방법론
권오현(Kwon O-hyeon),김명현(Kim Myeonghyeon),이성모(Rhee Sung-Mo),전경수(Chon Kyong Soo) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
Although the effectiveness of an express train's service is measured in "Total System Time or Cost" units many cases had used indirect method what based on the distintion by number of passengers in a station or experiential knowledgements. These methods are not guarantee itself as an optimal strategy. Focusing "Total System Time or Cost" directly this paper investigates the express train service's stop scheduling based on each OD-volume and trip time which mainly affect system time and cost. To do this we built an IP model which has a binary set presenting express train's stop scheduling as decision variable and suggest a Genetic Algorithm (GA) to find heuristic optimal solution.