• 한국인구학
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• 제2권1호
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• pp.5-16
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• 1978

The main purpose of this study is to examine the recent level of fertility and potentiality of the Korean population in Japan and to investigate some forces which influence the fertility of them using survey data. Some estimates of the level of fertility for the Korean population in Japan in 1974 are presented in Table 1. Comparing the some estimates for 1974 with those for 1969, the level of fertility in 1974 was realistically declined. It also indicated that potentiality of Koreans in Japan showed decreasing population. For investigating some factors affecting fertility, total births is selected which regressed on some variables believed in general to be influential in determiaing fertility. It was used a step-wise multiple regression to determine the independent as well as the combined effects of each of the variables. The SPSS computer program was used to perform the anlysis. Result from this data reveals that wife's family size preference as relevant predictor does influence the fertility of Koreans in Japan at this point considering that the age group of 20-29 is very much related. By employing multiple classification analysis, the analysis is concluded by nothing that the wi 3 family size preference has an even stronger relationship with economic factors than any other facto 3.

• 동의생리병리학회지
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• 제19권2호
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• pp.323-328
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• 2005

Oriental medicine specifies points which have proven to be valuable in the treatment of certain diseases or conditions of pain-the so-called master points and alarm points of the acupuncture system. The idea of applying colorpuncture via the master points already suggested itself on the basis of the very old correlations between organs and organ systems and colors which we find in a number of different therapeutic systems and trations. Each of the twelve organs of the acupuncture system has an alarm point which is usually not situated on the related meridian but on another channel. These alarm points are always to be found in the vicinity of the organs they are associated with. The combined use of master points and alarm points is a simple and excellent way of using colorpuncture. Via their inherent vibrational frequencies, the healings rays of colored light radiation are capable of releasing potent resonance forces within the organism, thus contributing to the alleviation and healing of acute and chronic diseases.

• 드라이브 ㆍ 컨트롤
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• 제13권2호
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• pp.1-9
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• 2016

In this paper, an elementary force fighting problem was investigated. The problem is encountered when a double-rod type EHA(electro-hydrostatic actuator) is combined with a single-rod type EHA to build a redundant actuator system with synchronized motion. When the rod-side chambers of the two different types of EHAs have the same effective piston areas and are simultaneously pressurized by an external load, the two EHAs behave identically, sharing the external load equally. However, when the piston head-side chamber of the single rod type EHA, having a larger effective area than the rod-side chamber, is pressurized by the external load, an abnormal force fighting between the two EHAs occurs, unless their pump speeds are properly decoupled. In this study, the output drive forces of each EHA were obtained from the cylinder pressure signals and applied to the position control for each EHA to maintain the balance between their pump speeds. Adding minor force difference feedback loops to the position control, the force fighting phenomena could be eliminated and steady state synchronization errors were reduced. The power consumption of the pumps also could be remarkably reduced, avoiding unnecessarily high load pressures to the pumps.

• Computers and Concrete
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• 제23권5호
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• pp.329-334
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• 2019

Traffic flow capacity of some old road bridges is insufficient due to limited deck width. In such cases bridge deck widening is a common solution. For multi-girder reinforced concrete (RC) bridges it is possible to add steel-concrete composite girders as the new outermost girders. The deck widening may be combined with bridge strengthening thanks to thickening of the existing deck slab. Joint action of the existing and the added parts of such bridge span must be ensured. It refers especially to the horizontal plane at the interface of the existing slab and the added concrete layer as well as to the vertical planes at the external surfaces of the initially outermost girders where the added girders are connected to the existing bridge span. Since the distribution of the added concrete is non-uniform in the span cross-section the structure is particularly sensitive to the added concrete shrinkage. The shrinkage induces shear forces in the aforementioned planes. Widening of a 12 m long RC multi-girder bridge span is numerically analysed to assess the influence of the added concrete shrinkage. The analysis results show that: a) in the vertical plane of the connection of the added and the existing deck slab the longitudinal shear due to the shrinkage of the added concrete is comparable with the effect of live load, b) it is necessary to provide appropriate longitudinal reinforcement in the deck slab over the added girders due to tension induced by the shrinkage of the added concrete.

• Smart Structures and Systems
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• 제24권4호
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• pp.525-539
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• 2019

In this study, vibration characteristics of a gravity-based caisson-foundation breakwater system are investigated for ambient and geometric parameters such as various waves, sea levels, and foundation conditions. To achieve the objective, following approaches are implemented. Firstly, operational modal analysis methods are selected to identify vibration modes from output-only dynamic responses. Secondly, a finite element model of an existing caisson-foundation breakwater system is established by using a structural analysis program, ANSYS. Thirdly, forced vibration analyses are performed on the caisson-foundation system for two types of external forces such as controlled impacts and wave-induced dynamic pressures. For the ideal impact, the wave force is converted to a triangular impulse function. For the wave flow, the wave pressure acting on the system is obtained from wave field analysis. Fourthly, vibration modes of the caisson-foundation system are identified from the forced vibration responses by combined use of the operational modal analysis methods. Finally, vibration characteristics of the caisson-foundation system are investigated under various waves, sea levels, and foundations. Relative effects of foundation conditions on vibration characteristics are distinguished from that induced by waves and sea levels.

• Structural Engineering and Mechanics
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• 제77권5호
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• pp.691-703
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• 2021

Reinforced concrete (RC) beams can be subjected to a complex combination of shear forces (V), torsional moments (T), flexural moments (M) and axial loads (N). This paper proposes a unified approach for the analysis of these elements. An existing model for the analysis of orthogonally reinforced concrete membrane elements subjected to in-plane shear and normal stresses is generalized to apply to the case of beams subjected to the complex loading. The combination of V and T can be critical. Torsion is modelled using the hollow-tube analogy. A direct equation for the calculation of the thickness of the equivalent hollow tube is proposed, and the shear stresses caused by V and T are combined using a simple approach. The development and the evaluation of the model are described. The calculations of the model are compared to experimental data from 350 beams subjected to various combinations of stress-resultants and to the calculations of the ACI and the CSA codes. The proposed model provides the most favorable results. It is also shown that it can accurately model the interaction between V and T. The proposed model provides a unified treatment of shear in beams subjected to complex stress-resultants and in thin membrane elements subjected to in-plane stresses.

• Structural Engineering and Mechanics
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• 제77권6호
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• pp.753-763
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• 2021

Feasibility studies of a reinforced concrete (RC) deep pile foundation system with the compressed air energy storage (CAES) technology were conducted in previous studies. However, those studies showed some technical limitations in its serviceability and durability performances. To overcome such drawbacks of the conventional RC energy pile system, various steel-concrete composite pile foundations are addressed in this study to be utilized as a dual functional system for an energy storage medium and load-resistant foundation. This study conducts finite element analyses to examine the applicability of various composite energy pile foundation systems considering the combined effects of structural loading, soil boundary forces, and internal air pressures induced by the thermos-dynamic cycle of compressed air. On this basis, it was clearly confirmed that the role of inner and outer tubes is essential in terms of reliable storage tank and better constructability of pile, respectively, and the steel tubes in the composite pile foundation can also ensure improved serviceability and durability performances compared to the conventional RC pile system.

• 풍력에너지저널
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• 제14권4호
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• pp.13-20
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• 2023

A self-climbing crane (SCC) system is under development for the installation and maintenance of wind turbines. It can move vertically along the wind turbine tower by itself. One of the key components of the SCC system is the clamping pad to maintain a safe position on the wind turbine tower. The SCC system can maintain its position on the tower from the frictional force generated between the surfaces of the clamping pads and the tower. If the frictional force provided by the clamping pads are insufficient, the SCC system cannot stay in the vertical position on the tower. Therefore, the development of clamping pads with sufficient frictional force is very important for the SCC system. At the same time, the operation of the SCC system should not damage the paint coating of the wind turbine tower. In order to verify that the frictional force is sufficient and that frictional and compressive forces do not cause damage to the paint, a number of combined compression and shear loading tests were conducted using a test device prepared for this study. The details regarding the test specimens, test procedure, and test results are summarized in this paper.

• 한국과 국제사회
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• 제1권2호
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• pp.209-242
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• 2017

본 연구의 목적은 군사력의 유 무형 전력을 효과적으로 통합하여 전투력상승효과(synergy)를 극대화시키는 '합동성(Jointness)'을 기반으로 이순신장군의 4대 대첩 리더십 분석과 제언을 통해 한국군의 무형전력의 핵심인 정신전력 강화에 기여하기 위함이다. 우리군의 효율성 증진을 위해 하드웨어 차원에서 군 구조개선을 하고 있는데, 이를 실질적으로 뒷받침 할 소프트웨어 차원에서 동맹국과 우리군의 합동성 추진과정을 분석한 결과 미래지향적인 정신전력 강화 시스템구축과 더불어 무형전력이 핵심인 리더십과 관련된 제반 과제들과 함께 조화롭게 혁신되어야 한다고 판단된다. 국방정신전력 강화를 위한 군 구조개혁과 함께 추진하여야 할 소프트웨어 차원의 한국군 리더십에 관한 과제를 도출하기 위하여 합동성과 연계한 연구문제(1. 합동성시대 서구 선진국가의 군 리더십의 핵심은 무엇인가? 2. 이순신장군의 전사(戰史)를 통한 한국적 리더십의 현대적 조명)를 선정하여 문헌조사 방법과 본 연구자의 참전당시 현지 인터뷰결과와 이순신장군의 4대 대첩을 중심으로 한 리더십 전사(戰史)를 모델로 고찰한 결과, 1) 미래를 예측하고 대비할 수 있는 전략적 리더십, 2) 상승효과를 발휘할 수 있는 융합의 리더십, 3) 전투중심으로 실천할 수 있는 지식의 리더십을 도출하게 되었다. 아울러 합동성을 기반으로 한 정신전력강화를 위해서는 첫째, 합동성 증진을 위한 심층깊고 실질적인 리더십진단이 선행되어야 하고, 둘째, 국방부와 육 해 공군 리더십센터와 PKO센터의 차별화와 통합에 관한 효율성을 과학적으로 비교분석한 후 국방개혁과 함께 합동성 증진을 위한 통합노력을 구현해야 하며, 셋째, 국방부 예하 무형전력 관련기관의 통폐합을 해야 한다는 결론에 도출하였다.

• 해양안보
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• 제5권1호
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• pp.113-136
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• 2022

본 논문은 중국의 서해 내해화 전략을 분석하여 해양에 종사하거나, 해양 정책을 연구하는 이들에게 시사점을 제공하기 위해 작성하였다. 이를 위해 최근 서해에서 이루어지고 있는 중국의 해상활동을 아더 라이케가 제시한 전략 구성요소인 목표(Ends), 방법(Ways) 및 수단(Means)의 세 가지 기준으로 분석하였다. 연구 결과, 중국은 서해 내해화라는 목표를 달성하기 위해 국가 차원에서 제 요소를 복합적으로 활용한다는 결과를 도출할 수 있었다. 중국은 ① 정전 상태에 있는 한반도의 특수한 안보 환경을 이용하여 북방한계선(NLL, Northern Limit Line) 인근에서 자국 어선들의 불법조업을 의도적으로 방조하여 서해를 영해로 기정사실화하며, ② 자국의 국가안보에 대한 위협을 이유로 서해상 한･미 연합훈련을 거부하는 한편, 동 해역 내 군사훈련을 확대하고 군용기를 한국방공식별구역 인근으로 상시 진입하게 하여 군사적 능력을 과시하고, ③ 과학탐구를 빙자하여 서해에 각종 시설을 확대 설치하고 있다. 필자가 본 연구를 통해 강조하고 싶은 것은 '서해에서 자행되는 일부 중국의 활동은 한국의 주권을 심각하게 침해하는 행위이며, 한국은 서해에서 국민의 자유로운 해양 활동과 안전을 보장하기 위해 한미 연합전력 중심의 비례적 대응을 해야 한다는 것'이다.