• 환경영향평가
• /
• 제24권3호
• /
• pp.205-216
• /
• 2015

전 지구와 남한, 북한, 일본 지역을 중심으로 한 동북아시아 지역에 대한 기온, 강수량, 일사량의 미래 변화를 정량적으로 평가하기 위해 총 34개 GCM에 의해 작성된 CMIP5 기후변화 시나리오를 분석하였다. 그 결과 동북아시아 지역에서 전 지구 평균보다 기온과 강수량이 증가하는 것으로 예측되었다. 특히 RCP 8.5 시나리오의 2080년대 북한 지역에서는 비록 GCM 간 예측의 불확실성이 크지만 과거 30년(1971-2000년)에 비해 기온은 $5.1^{\circ}C$, 강수량은 18% 증가하는 것으로 예측되었다. 일사량의 경우 전 지구 평균 일사량은 RCP 2.6 시나리오를 제외한 모든 RCP 시나리오에서 대체로 시간이 경과할수록 감소하는 것으로 예측되었으나 동북아시아 지역에서는 대체로 시간이 경과할수록 운량 감소의 영향으로 일사량이 증가하는 것으로 예측되었다.

• Smart Structures and Systems
• /
• 제18권5호
• /
• pp.983-1004
• /
• 2016

Nowadays, there are two classes of methods for damage detection in structures consisting of static and dynamic. The dynamic methods are based on studying the changes in structure's dynamic characteristics. The theoretical basis of this method is that damage causes changes in dynamic characteristics of structures. The dynamic methods are divided into two categories: signal based and modal based. The modal based methods utilize the modal properties consisting of natural frequencies, modal damping and mode shapes. As the modal properties are sensitive to changes in the structure, these can be used for detecting the damages. In this study, using dynamic method and modal based approach (natural frequencies and mode shapes), the objective function is formulated. Then, detection of damages of truss structures is addressed by using Simplified Dolphin Echolocation algorithm and solving inverse optimization problem. Many scenarios are used to simulate the damages. To demonstrate the ability of the algorithm, different truss structures with several multiple elements scenarios are tested using a few runs. The influence of the two different levels of noise in the modal data for these scenarios is also considered. The last example of this article is investigated using a different mutation. This mutation obtains the exact answer with fewer loops and population by limited computational effort.

• Journal of Communications and Networks
• /
• 제18권6호
• /
• pp.913-925
• /
• 2016

In-band wireless full-duplex is a promising technology that enables a wireless node to transmit and receive at the same time on the same frequency band. Due to the complexity of self-interference cancellation techniques, only base stations (BSs) are expected to be full-duplex capable while user terminals remain as legacy half-duplex nodes in the near future. In this case, two different nodes share a single subchannel, one for uplink and the other for downlink, which causes inter-node interference between them. In this paper, we investigate the joint problem of subchannel assignment and power allocation in a single-cell full-duplex orthogonal frequency division multiple access (OFDMA) network considering the inter-node interference. Specifically, we consider two different scenarios: i) The BS knows full channel state information (CSI), and ii) the BS obtains limited CSI through channel feedbacks from nodes. In the full CSI scenario, we design sequential resource allocation algorithms which assign subchannels first to uplink nodes and then to downlink nodes or vice versa. In the limited CSI scenario, we identify the overhead for channel measurement and feedback in full-duplex networks. Then we propose a novel resource allocation scheme where downlink nodes estimate inter-node interference with low complexity. Through simulation, we evaluate our approaches for full and limited CSIs under various scenarios and identify full-duplex gains in various practical scenarios.

• Nuclear Engineering and Technology
• /
• 제45권5호
• /
• pp.625-636
• /
• 2013

Pressing demands of economic competitiveness, the need for large-scale deployment, minimizing the need of human intervention, and experience from the past events and incidents at operating reactors have guided the evolution and innovations in reactor technologies. Indian innovative reactor 'AHWR' is a pressure-tube type natural circulation based boiling water reactor that is designed to meet such requirements, which essentially reflect the needs of next generation reactors. The reactor employs various passive features to prevent and mitigate accidental conditions, like a slightly negative void reactivity coefficient, passive poison injection to scram the reactor in event of failure of the wired shutdown systems, a large elevated pool of water as a heat sink inside the containment, passive decay heat removal based on natural circulation and passive valves, passive ECC injection, etc. It is designed to meet the fundamental safety requirements of safe shutdown, safe decay heat removal and confinement of activity with no impact in public domain, and hence, no need for emergency planning under all conceivable scenarios. This paper examines the role of the various passive safety systems in prevention and mitigation of severe plant conditions that may arise in event of multiple failures. For the purpose of demonstration of the effectiveness of its passive features, postulated scenarios on the lines of three major severe accidents in the history of nuclear power reactors are considered, namely; the Three Mile Island (TMI), Chernobyl and Fukushima accidents. Severe plant conditions along the lines of these scenarios are postulated to the extent conceivable in the reactor under consideration and analyzed using best estimate system thermal-hydraulics code RELAP5/Mod3.2. It is found that the various passive systems incorporated enable the reactor to tolerate the postulated accident conditions without causing severe plant conditions and core degradation.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
• /
• 제15권9호
• /
• pp.649-660
• /
• 2009

유비쿼터스 환경에서 사용자의 상황에 부합하는 서비스를 제공하기 위해 기존의 서비스를 합성 하여 새로운 서비스를 제공하는 방안에 대한 연구가 점점 증가하고 있다. 그러나 다수의 사용자들이 존재하는 서비스 공간에서 사용자에게 개인화된 서비스를 제공하는 것은 매우 어려운 일이다. 본 논문은 사용자 중심의 서비스 시나리오에 기반한 서비스 합성 모델을 제안하고 사용자의 상황에 필요한 서비스를 동적으로 발견하고 결합하여 개인화된 서비스를 제공하는 시스템을 제안한다. 이 시스템은 유비쿼터스 공간에 존재하는 이질적이고 제한된 자원을 가지는 다양한 스마트 객체들로부터 필요한 서비스를 찾기 위한 서비스 발견 프로토콜을 지원한다. 또한 제안된 시스템은 사용자로부터 파생되는 다양한 서비스 시나리오와 정보의 저장소 및 사용자에게 필요한 서비스 실행기로서의 역할을 수행한다. 본 논문에서는 제안한 시스템을 검증하기 위하여 휴대용 단말기를 위한 프로토타입 시스템을 구현한다.

• 한국농공학회논문집
• /
• 제56권4호
• /
• pp.59-68
• /
• 2014

Climate change influences multiple environmental aspects, certain of which are specifically related to agricultural water resources such as water supply, water management, droughts and floods. Understanding the impact of climate change on reservoirs in relation to the passage of time is an important component of water resource management for stable water supply maintenance. Changes on rainfall and hydrologic patterns due to climate change can increases the occurrence of reservoir water shortage and affect the future availability of agricultural water resources. It is a main concern for sustainable development in agricultural water resources management to evaluate adaptation capability of water supply under the future climate conditions. The purpose of this study is to predict the sustainability of agricultural water demand and supply under future climate change by applying an irrigation vulnerability assessment model to investigate evidence of climate change occurrences at a local scale with respect to potential water supply capacity and irrigation water requirement. Thus, it is a recommended practice in the development of water supply management strategies on reservoir operation under climate change.

• Earthquakes and Structures
• /
• 제10권4호
• /
• pp.867-891
• /
• 2016

This paper addresses numerically the behavior of steel structures under Fire-after-Earthquake (FAE) loading. The study is focused on a four-storey library building and takes into account the damage that is induced in structural members due to earthquake. The basic objective is the assessment of both the fire-behavior and the fire-resistance of the structure in the case where the structure is damaged due to earthquake. The combined FAE scenarios involve two different stages: during the first stage, the structure is subjected to the ground motion record, while in the second stage the fire occurs. Different time-acceleration records are examined, each scaled to multiple levels of the Peak Ground Acceleration (PGA) in order to represent more severe earthquakes with lower probability of occurrence. In order to study in a systematic manner the behavior of the structure for the various FAE scenarios, a two-dimensional beam finite element model is developed, using the non-linear finite element analysis code MSC-MARC. The fire resistance of the structure is determined using rotational limits based on the ductility of structural members that are subjected to fire. These limits are temperature dependent and take into account the level of the structural damage at the end of the earthquake and the effect of geometric initial imperfections of structural members.

• 국제초고층학회논문집
• /
• 제7권2호
• /
• pp.111-125
• /
• 2018

By the year 2050, the world population is set to increase to 9 billion people, of which 66% will be living in cities. It is argued that this will inevitably lead to further urban densification and soaring, inhumane and dense vertical environments. However, innovative and disruptive technologies impacting all realms of life means that we will also live, work, play, learn and make in novel ways, the beginnings of which are already becoming evident. These present opportunities for reimagining city environments, and in particular tall buildings, with a focus on reducing redundancies and re-appropriating existing buildings, creating novel hybrid environments, incorporating green and social democratic spaces, and integrating multiple modes of transport. This paper examines how vertical cities may perhaps be dense, resource efficient, and yet humane, presenting three possible scenarios for Singapore's context, which are, however, common to many Asian high-density urban environments. The scenarios presented are the outcome of Final-Year Thesis Projects undertaken by final-year architecture students at the National University of Singapore (NUS) in 2017.

• Structural Engineering and Mechanics
• /
• 제62권4호
• /
• pp.465-475
• /
• 2017

Photovoltaic (PV) panels are used in high-rise buildings to convert solar energy to electricity. Due to the considerable energy consumption of high-rise buildings, applying PV technology is of great significance to energy saving. In the application of PV panels, one of the most important construction issues is the connection of the PV panel with the main structures. One major difficulty of the connection design is that the PV panel connection consists of two separate components with coupling and indeterminate dimension. In this paper, the gap element is employed in these two separated but coupled components, i.e., hook and catch. Topology optimization is applied to optimize and design the cross-section of the PV panel connection. Pareto optimization is conducted to operate the optimization subject to multiple load scenarios. The initial design for the topology optimization is determined by the common design specified by the Technical Code for Glass Curtain Wall Engineering (JGJ 102-2003). Gravity and wind load scenarios are considered for the optimization and numerical analysis. Post analysis is conducted for the optimal design obtained by the topology optimization due to the manufactory requirements. Generally, compared with the conventional design, the optimized connector reduces material use with improved structural characteristics.

• 산업공학
• /
• 제13권4호
• /
• pp.619-626
• /
• 2000

In this paper, we place the focus on suggesting a method of forecasting demand for PCS resale service with survey data in Korea. It is important for the service provider to forecast the diffusion process when designing marketing strategies and analyzing the costs and benefits. For the reason, we conduct a survey of three groups composed of non-subscribers, cellular subscribers, and PCS subscribers in order to forecast the demand according to several possible scenarios and business strategies. We consider the survey item that is measured by multiple point scales in response to a question if he would subscribe to the mobile telephone service in the future. We propose a method to forecast the size of market potential by classifying each individual into the two extreme groups, that is, yes or no. Then, by integrating survey data and historical data, we forecast the demand for PCS resale service that varies according to scenarios and strategies. From the results, we can find several implications for the provider of PCS resale service.