• Wind and Structures
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• 제31권2호
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• pp.143-152
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• 2020

The wind design of buildings is typically based on strength provisions under ultimate loads. This is unlike the ductility-based approach used in seismic design, which allows inelastic actions to take place in the structure under extreme seismic events. This research investigates the application of a similar concept in wind engineering. In seismic design, the elastic forces resulting from an extreme event of high return period are reduced by a load reduction factor chosen by the designer and accordingly a certain ductility capacity needs to be achieved by the structure. Two reasons have triggered the investigation of this ductility-based concept under wind loads. Firstly, there is a trend in the design codes to increase the return period used in wind design approaching the large return period used in seismic design. Secondly, the structure always possesses a certain level of ductility that the wind design does not benefit from. Many technical issues arise when applying a ductility-based approach under wind loads. The use of reduced design loads will lead to the design of a more flexible structure with larger natural periods. While this might be beneficial for seismic response, it is not necessarily the case for the wind response, where increasing the flexibility is expected to increase the fluctuating response. This particular issue is examined by considering a case study of a sixty-five-story high-rise building previously tested at the Boundary Layer Wind Tunnel Laboratory at the University of Western Ontario using a pressure model. A three-dimensional finite element model is developed for the building. The wind pressures from the tested rigid model are applied to the finite element model and a time history dynamic analysis is conducted. The time history variation of the straining actions on various structure elements of the building are evaluated and decomposed into mean, background and fluctuating components. A reduction factor is applied to the fluctuating components and a modified time history response of the straining actions is calculated. The building components are redesigned under this set of reduced straining actions and its fundamental period is then evaluated. A new set of loads is calculated based on the modified period and is compared to the set of loads associated with the original structure. This is followed by non-linear static pushover analysis conducted individually on each shear wall module after redesigning these walls. The ductility demand of shear walls with reduced cross sections is assessed to justify the application of the load reduction factor "R".

• 디지털융복합연구
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• 제11권12호
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• pp.41-47
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• 2013

국내 미디어기업에 대한 경영전략 사례 연구가 극히 드문 상황에서, 본 연구는 대표적인 뉴미디어 콘텐츠 기업인 CJ E&M에 대한 사례분석을 실시했다. 분석틀로는 CJ E&M의 출범과 다각화 과정에 대해서는 진화론적 관점을 적용하고, 출범 이후는 외부환경분석과 자원준거관점에 기반한 내부역량분석을 실시했다. CJ E&M은 그동안 수평 수직 다각화를 통해 규모의 시너지를 높이고, 타 미디어기업과는 달리 콘텐츠 강화 전략을 꾸준하게 전개한 점이 돋보인다. 또 엔터테인먼트 미디어 산업에 대한 열정과 의지의 리더십, 전문성 높은 인적 구성, 유연하고 창의적인 기업 문화, 효과적인 콘텐츠 포트폴리오 구성 등이 CJ E&M을 국내 미디어 선도기업으로 이끈 원동력이라고 평가할 수 있다. 그러나 경쟁과 성과를 지나치게 강조하는 조직 분위기와 오너의 의지에 따라 주요 사업이 결정되는 기업구조는 오히려 조직문화를 경색시키고 글로벌 경쟁력을 약화시킬 수 있다는 점을 주지할 필요가 있다.

• Smart Structures and Systems
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• 제20권3호
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• pp.273-283
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• 2017

This paper presents and compares three feedback control strategies for active control of noise inside a 3-D vibro-acoustic cavity. These are a) control strategy based on direct output feedback (DOFB) b) control strategy based on linear quadratic regulator (LQR) to reduce structural vibrations and c) LQR control strategy with a weighting scheme based on structural-acoustic coupling coefficients. The first two strategies are indirect control strategies in which noise reduction is achieved through active vibration control (AVC), termed as AVC-DOFB and AVC-LQR respectively. The third direct strategy is based on active structural-acoustic control (ASAC). This strategy is an LQR based optimal control strategy in which the coupling between the various structural and the acoustic modes is used to design the controller. The strategy is termed as ASAC-LQR. A numerical model of a 3-D rectangular box cavity with a flexible plate (glued with piezoelectric patches) and with other five surfaces treated rigid is developed using finite element (FE) method. A single pair of collocated piezoelectric patches is used for sensing the vibrations and applying control forces on the structure. A comparison of frequency response function (FRF) of structural nodal acceleration, acoustic nodal pressure, and piezoelectric actuation voltage is carried out. It is found that the AVC-DOFB control strategy gives equal importance to all the modes. The AVC-LQR control strategy tries to consume the control effort to damp all the structural modes. It is seen that the ASAC-LQR control strategy utilizes the control effort more intelligently by adding higher damping to those structural modes that matter more for reducing the interior noise.

• Steel and Composite Structures
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• 제34권5호
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• pp.625-641
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• 2020

The realistic modeling of the beam-column semi-rigid connection in steel frames attracted the attention of many researchers in the past for the seismic analysis of semi-rigid frames. Comparatively less studies have been made to investigate the behavior of steel frames with semi-rigid connections under different types of earthquake. Herein, the seismic behavior of semi-rigid steel frames is investigated under both far and near-field earthquakes. The semi-rigid connection is modeled by the multilinear plastic link element consisting of rotational springs. The kinematic hysteresis model is used to define the dynamic behavior of the rotational spring, describing the nonlinearity of the semi-rigid connection as defined in SAP2000. The nonlinear time history analysis (NTHA) is performed to obtain response time histories of the frame under scaled earthquakes at three PGA levels denoting the low, medium and high-level earthquakes. The other important parameters varied are the stiffness and strength parameters of the connections, defining the degree of semi-rigidity. For studying the behavior of the semi-rigid frame, a large number of seismic demand parameters are considered. The benchmark for comparison is taken as those of the corresponding rigid frame. Two different frames, namely, a five-story frame and a ten-story frame are considered as the numerical examples. It is shown that semi-rigid frames prove to be effective and beneficial in resisting the seismic forces for near-field earthquakes (PGA ≈ 0.2g), especially in reducing the base shear to a considerable extent for the moderate level of earthquake. Further, the semi-rigid frame with a relatively weaker beam and less connection stiffness may withstand a moderately strong earthquake without having much damage in the beams.

• 보건행정학회지
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• 제8권2호
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• pp.25-57
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• 1998

In order to assess the attractiveness of the hospital industry, the competitive environment of the industry was analyzed. With the employment of Michael Porter's five forces model' the deciding factor was examined and applied to evaluate the intensity of the competitiveness in the hospital industry, and then the structure and attractiveness in hospital industry was assessed. The subject of this study was hospitals that have over 500 beds. Main findings are as follows. 1. Out of 5 factors deciding competitiveness, the pressure from newly opened hospitals and the competition between existing hospitals, were both high in intensity; this makes hospital industry less attractive. The pressure from the substitutes and the pressure from the negotiating power of consumers and suppliers were low; this makes hospital industry more attractive. 2. Overall intensity of competitive pressure pressure for existing hospital industry that have over 500 beds was rather low, consequently the attractiveness of the industry was evaluated quite high. These findings, however, were not solid enough to endorse the attractiveness of the industry. 3. It was understood that future industry would have bigger pressure/ competition so that the attractiveness for the relevant hospital industry would be decreased. This study has its limitations. As the evaluation of competitive factor was not grounded on quantitative data, its objectivity could be questioned. Also, the overall result of each factors could be distorted as it was calculated with same weight against individual factor. This study has its significance in that the specific hospital group was viewed as one industry, and its attractiveness as a potentially profitable industry in which worth investing was estimated, with all factors considered. With this key result, hospitals industustry could work out a plan to enhance the status of hospitals, allowing hospitals to get assistance in making strategic decisions such as mergers, cooperations, and new establishments.

• 대한치과교정학회지
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• 제41권5호
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• pp.361-370
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• 2011

Objective: Speedy surgical orthodontics (SSO), an innovative orthodontic treatment, involves the application of orthopedic forces against temporary skeletal anchorage devices following perisegmental corticotomy to induce movement of specific dental segments. Herein, we report the biological effects of SSO on the teeth and periodontal structures. Methods: Five beagle dogs were divided into 2 groups and their 6 maxillary incisors were retracted $en$ $masse$ by applying 500 g orthopedic force against a single palatal mini-plate. Retraction was performed without and with perisegmental corticotomy in groups I and II, respectively. All animals were killed on the 70th day, and their periodontal structures were processed for histologic analyses and scanning electronic microscopy (SEM). The linear distance between the third maxillary incisor and canine was used as a benchmark to quantify the retraction amount. Results: Retraction was markedly faster and retraction amount greater in group II than in Group I. Surprisingly, Group II did not show any root resorption despite extensive retraction, while Group I showed prominent root surface irregularities. Similarly, SEM showed multiple resorption lacunae in Group I, but not in Group II. Conclusions: SSO is an effective and favorable orthodontic approach for major en masse retraction of the maxillary anterior teeth.

• 한국해안·해양공학회논문집
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• 제27권6호
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• pp.443-451
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• 2015

유수실을 두 개 가지는 유공케이슨에 작용하는 파력 산정식은 아직까지 없다. 이 연구에서는 이러한 이중유수실 케이슨 모형에 작용하는 파력을 측정한 수리실험 자료 분석 결과를 제시하였다. 실험결과로부터 세 가지 연직벽체에 작용하는 파력의 첨두값에 연관된 다섯 가지 파의 위상에 따른 파력의 변화 양상을 명확하게 규명할 수 있었으며, 이로부터 Takahashi and Shimosako (1994)와 유사한 형태의 이중유수실 파력보정계수를 산정하였다. 이 결과는 향후 추가 실험 및 현장 실무에의 적용을 통해 검증될 필요가 있다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.407-407
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• 2019

According to Asian Development Bank report Pakistan is among water scarce countries. Climate scenario on the basis IPCC fifth assessment report (AR5) revealed that annual mean temperature of Pakistan from year 2010-2019 was $17C^o$ which will rise up to $21C^o$ at the end of this century, similarly almost 10% decrease of annual rainfall is expected at the end of the century. It is a changing task in underdeveloped countries like Pakistan to meet the water demands of rapidly increasing population in a changing climate. While many studies have tackled scarcity and stream flow forecasting of the Upper Indus Basin (UIB) Pakistan, very few of them are related to socio-economic and climate change impact on sustainable water management of UIB. This study investigates the pattern of current and future surface water availability for various demand sites (e.g. domestic, agriculture and industrial) under different socio-economic and climate change scenarios in Upper Indus Basin (UIB) Pakistan for a period of 2010 to 2050. A state-of-the-art planning tool Water Evaluation and Planning (WEAP) is used to analyze the dynamics of current and future water demand. The stream flow data of five sub catchment (Astore, Gilgit, Hunza, Shigar and Shoyke) and entire UIB were calibrated and validated for the year of 2006 to 2011 using WEAP. The Nash Sutcliffe coefficient and coefficient of determination is achieved ranging from 0.63 to 0.92. The results indicate that unmet water demand is likely to increase severe threshold and the external driving forces e.g. socio-economic and climate change will create a gap between supply and demand of water.

• 대한토목학회논문집
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• 제44권1호
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• pp.19-32
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• 2024

정밀안전진단보고서를 분석한 결과 국내 고속도로 교량은 결함, 열화, 물리력에 의한 손상이 주요하게 발생한다. 특히 열화는 시간이 경과함에 따라 다양한 환경 영향인자와 외부적 요인에 의해 발생하는 필연적인 손상이다. 교량 바닥판의 경우 열화가 가장 빠른 부재로, 균열부를 중심으로 철근부식, 박리/박락 등의 여러 가지 유형의 이종손상이 함께 발생하는 것으로 분석된다. 따라서 교량의 이종손상과 열화환경 간의 상관관계를 밝히고 이를 통해 교량의 이종손상 발생 원인을 규명해야 한다. 본 연구에서는 랜덤포레스트를 활용하여 교량의 이종손상 예측 모델을 개발하였으며, 개발된 모델을 통해 이종손상 발생에 영향을 미치는 상위 5가지 영향인자를 도출하였다. 이를 통해 장래 교량의 유지관리 및 예산을 추정하는 분야에 활용하는 기초자료가 될 수 있을 것으로 판단된다.

• 대한간호학회지
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• 제23권1호
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• pp.118-129
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• 1993

In order to approach the nursing care of clients who are using oriental medicine and to understand the perception of the client who uses oriental medicine practices and the need to develop a model of nursing related to oriental medicine it is important to examine the major nursing concepts as they are found in oriental medicine and as they are differently defined according to the basic thought, theory and philosophical perspectives between East and West. Oriental medicine developed based on Sung Confucianism the teachings of Chut-zu, especially Tai-Chi-Tu Shuo and energy thought which are similar to traditional Korean Sasang Constitutional medicine. The basic theory on which oriental medicine is build is the theory of the five elements of Yin / Eum-Yang Theory(cosmic dual forces) and Meridian Theory. The most important attribute of Yin Yang is the concept of duality, confrontation and dependence, within Yin Yang but which do not exist separately. That is, the universe is a vast, indivisible entity within which all things exist in harmonious interdependence and balance. Harmony is achieved only when the two primorial forces, Yin and Yang, are brought into perfect balance. Each is contained within the other and there is a continuing interchange between the two. This also applies to the human body including human health which is defined as balanced harmony. The most universal connection of Yin and Yang is found in the universe where the five elements of life, fire, water, earth, wood and metal can be explained as having either Yin or Yang and therefore being in a state of connectedness but systematically circulating between the two, that is essentalilly one (the control of the unified ) or as coexistant poles of individual wholes (the pluralism of Yin Yang Theory) so that it is all unified(balanced) in the Great Absoulte. Human beings also maintain a balance of Yin and Yang in the five elements and this relationship is very important in approaching ·oriental medicine, The meridians are the channels in the body through which the life force flow throughout the body. In oriental medicine the meridians are seen as the railroad, the acupuncture points on the meridians as the stations and energy as the train. In the normal healthy organism, all are maintained in balance and in a contiuous circulation of energy. illness is the result of the energy flow becoming disarranged. Although practitioners of oriental medicine approach the client differently than do practitioners of Western medicine and their method of examining the patient is different, the basic objectives of the examination are the same for practitioners of both types of medicine. Therefore if each could be used to supplement the defiencies in the other and achieve a harmonious cooperation between the two, a higher level of care which is culturally appropriate to korean culture could be achieved. The traditional korean concept of health is a naturalistic view which emphasizes being in harmony with nature. Any manifestation of disease is considered a sign that the body is in a state of disequilibrium and is thus no longer in harmony with the universe. The wholistic view of the world held by practitioners of oriental medicine can be used by nursing in the development of a world view of nursing in which the human being is seen within the macrocosm as part of the natural phenomenon of the universe and but also as a microcosm of the universe, a universe which is a vast and indivisible entity within which all things exist in harmonious interdependence and balance. Interaction between human beings and their environment and the relationship of this interaction to health are concepts that are also found in nursing. Nursing views human brings, not as an accumulation of separate cells and organs but, as unified wholes interacted in very close relationship nth their environment. Nursing also maintains a view of human beings in which emphasis is placed on the role of the mind in explaining the concepts of harmony and balance in health. Although there are differences between oriental medicine and nursing in approaches to clients, the basic point of view and philosophy have many fundamental similarites. An understanding of the basic thought and philosophy of oriental medicine if applied to nursing, would allow for the development, not only of nursing related to oriental medicine, but of a nursing theory appropriate to the korean context.