• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.74-89
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• 2021

For higher-level requirements of urban planning and management and the recent development of "digital earth" and "digital city", it is urgent to establish protocols for the construction of three-dimensional digital city models. However, some problems still exist in the digital technology of the three-dimensional city model, such as insufficient precision of the three-dimensional model, not optimizing the scene and not considering the constraints of building codes. In view of those points, a method to interactively simulate a virtual city scene based on building codes is proposed in this paper. Firstly, some constraint functions are set up to restrict the models to adhere to the building codes, and an improved directional bounding box technique is utilized to solve the problem that geometric objects may intersect in a virtual city scene. The three-dimensional model invocation strategy is designed to convert two-dimensional layouts to a three-dimensional urban scene. A Leap Motion hardware device is used to interactively place the 3D models in a virtual scene. Finally, the design and construction of the three-dimensional scene are completed by using Unity3D. The experiment shows that this method can simulate urban virtual scenes that strictly adhere to building codes in a virtual scene of the city environment, but also provide information and decision-making functions for urban planning and management.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.58-58
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• 2011

동해를 전파하는 지진해일은 다른 지역에서 발생하는 지진해일과 비교하였을 때 상대적으로 파장이 짧고, 파장에 비해 먼거리를 전파한다. 따라서 지진해일이 전파할 시 물리적인 분산효과가 매우 중요하다. 그러므로 동해에서 발생하는 지진해일을 수치모의 할 때는 분산효과가 충분히 고려될 수 있는 선형 Boussinesq 방정식을 사용한다. 그러나 이를 직접 풀 경우에는 상당히 많은 시간이 소비되며 효율적이지 못하다. 이와 같은 단점을 극복하기 위해 기존의 연구에서는 leap-frog 기법을 사용하여 선형 천수방정식을 차분할 때 발생하는 수치분산항을 선형 Boussinesq 방정식의 분산항과 같은 형태를 가질 수 있도록 분산보정계수를 사용하여 수치모의를 수행하였다. 하지만 이때 사용된 지배방정식은 수심이 일정하다는 가정을 이용하여 유도된 것이므로, 실제 경사가 있는 지형을 통과할 때의 수치모의 결과는 정확하다고 할 수 없다. 본 연구에서는 이를 극복하기 위하여 바닥 지형이 1차원으로 변한다는 가정으로 새로운 지배방정식을 유도하였으며, 수심변화로 인해 새로 발생하는 항을 기존의 분산보정기법에 추가하였다. 또한 수심이 변화는 지형을 통과하는 지진해일의 분산효과가 충분히 고려되는지 확인하기 위하여 Gaussian hump를 이용하여 가상 지진해일을 원형 천퇴지형에 통과시키는 수치모의를 수행하였다. 결과의 비교를 위한 정확해가 없으므로, 비선형 Boussinesq 방정식을 직접 차분하여 푸는 FUNWAVE를 이용하여 동일한 조건으로 수치모의를 수행하였다. 수치모의 시 중심선에 4개의 가상 gage를 설치하였으며, 이를 통해 각각의 수치모의 실험에 대한 자유수면 변위를 관찰하여 비교하였다. 수치모의 결과에 대한 비교를 통하여 기존의 분산보정기법에 비해 본 연구에서 제안한 새로운 수치기법이 분산효과를 비교적 잘 반영하는 것으로 나타났으며, 비교적으로 실제 지형에 적용하였을 때 정확도 향상의 가능성이 높다고 판단하였다.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.150-159
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• 2014

Since the release of mid-term domestic GHG goals until 2020, in 2009, some various GHG reduction policies have been proposed. There are two types of modeling approaches for identifying options required to meet greenhouse gas (GHG) abatement targets and assessing their economic impacts: top-down and bottom-up models. Examples of the bottom-up optimization models include MARKAL, MESSAGE, LEAP, and AIM, all of which are developed based on linear programming (LP) with a few differences in user interface and database utilization. In this paper, we suggest a simplified LP formulation and how can build it through step-by-step procedures.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.40-41
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• 2011

동해를 전파하는 지진해일은 세계적으로 다른 지역에서 발생하는 지진해일과 비교하였을 때 상대적으로 파장이 짧고, 이에 비해 먼 거리를 전파한다. 그러므로 동해에서 발생한 지진해일의 전파에 대한 해석을 수행할 때 물리적인 분산효과가 매우 중요하다. 따라서 지배방정식으로 분산 효과가 충분히 고려된 선형 Boussinesq 방정식을 사용한다. 기존의 연구에서는 leap-frog 기법을 사용하여 선형 천수방정식을 차분할 때 발생하는 수치분산항에 분산 보정계수를 이용하여 선형 Boussinesq 방정식의 물리적 분산항과 같은 형태로 나타나도록 유도하여 수치모의를 수행하였다. 그러나 기존에 사용한 지배방정식은 수심이 일정하다는 가정을 통하여 유도된 것으로, 수심에 변화가 있는 실제 지형을 통과하는 지진해일에 대한 수치모의를 수행한 결과의 정확도에 문제가 생길 수 있다. 본 연구에서는 기존의 연구에서 발생할 수 있는 수심 변화에 따른 오류를 개선하기 위하여 바닥 지형이 1차원으로 변한다는 가정을 이용하여 지배방정식을 유도하였으며, 이로 인해 발생하는 수심 변화가 고려된 항을 기존의 분산보정기법에 추가하였다. 그리고 적용성을 높이기 위하여 수치모의 기법의 제한을 최소화하는 연구를 진행하였다. 본 연구에서 제안한 수정 기법이 수심이 변화하는 지형을 전파하는 지진해일 수치모의 과정에서 경사에 대한 분산효과가 충분히 고려되는지 확인하기 위하여 Gaussian hump를 이용한 가상 지진해일을 원형 천퇴 지형에 통과시켰다. 본 연구에서 사용한 지형을 통과하는 Gaussian hump에 대한 해석해를 구하는 방법이 존재하지 않으므로, Boussinesq 방정식을 직접 차분하여 푸는 FUNWAVE를 사용하여 동일한 조건 하에서 수치모의를 수행하였다. 비교 결과를 통하여 본 연구에서 제안한 기법의 정확도 향상을 확인하게 되면, 실제 지형을 통과하는 지진해일의 수치모의에 대한 활용성을 높일 수 있을 것이다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.95-102
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• 2006

The PPT being currently developed for the flight model represents a significant leap in techniques and technology compared to the previous flight ones. The electrical energy to be charged in the pulsed plasma thruster (PPT) is a very important aspect to provide an uniform impulse bit ,, and a specific impulse ,, for satellite attitude control. In this paper, we propose a nonlinear control technique and a stability analysis based on the Lyapunov function for the pulsed plasma thruster. Specifically, the proposed control law guarantees to charge and discharge the electrical energy generated from the power processing unit (PPU) within the specified time.

• Journal of the Korea Convergence Society
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• v.12 no.5
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• pp.121-126
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• 2021

Based on network agenda-setting theory, this study attempted to analyze media reports about suicide from 2000 to 2020 in order to find solutions for suicide problem in the Korean society. Results showed that top 10 key words in media were suicide, death leap, death, attempt, supposition, discovery, men, pessimism. Those key words were appeared similarly and contunually in the media. In addition, both newspapers and broadcastings had similar reports trend, so it is plausible to consider inter-media agenda setting relations between newspapers and broadcasings.

• Journal of Korean Public Health Nursing
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• v.36 no.3
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• pp.402-416
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• 2022

Purpose: The goal of this study was to define and clarify the concept of 'rehabilitation' of stroke patients in the elderly. Method: For analyzing the concept of rehabilitation, this study used the hybrid model, which involves an in depth interview six stroke patients. Result: The concept of rehabilitation of patients with a stroke condition can be categorized with two dimensions; overcoming, new recovery aspects. Besides, three attributes and twelve indicators were analyzed. The concept of rehabilitation of patients with a stroke condition can be expressed as one of the following processes; It can be said that it is a process of accepting and overcoming one's physical limitations in order to overcome, and to grow resilience by making a leap from crisis to recovery with inner enforcement in dimension of new recovery. Conclusion: The rehabilitation is important for stroke conditioned patients in order to control their disease in the long term. The attributes and indicators drawn by this study could be used for tool development and useful resources of rehabilitation competence for stroke conditioned patients.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.279-289
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• 2021

GNSS receivers capable of tracking multiple Global Navigation Systems (GNSSs) simultaneously are widely used. In order to estimate accurate user position and velocity, it is necessary to consider the key elements that contribute to the interoperability of the different GNSSs. Typical examples are the time system and the coordinate system. Each GNSS is operated based on its own reference time system depending on when the system was developed and whether the leap seconds are applied. In addition, each GNSS is designed based on its own coordinate system based on earth model constant values. This paper addresses the interoperability issues from the viewpoint of Single Point Positioning (SPP) users utilizing multiple GNSS signals from GPS, GLONASS, BeiDou, and Galileo. Since the broadcast ephemerides of each GNSS are based on their own time and coordinate systems, the time and the coordinate systems should be unified for any user algorithm. For this purpose, this paper proposes a method of converting each GNSS coordinate system into the reference coordinate system through Helmert transformation. The error of the broadcast ephemerides was calculated with the precise ephemerides provided by the International GNSS Service (IGS). The effectiveness of the proposed multi-GNSS correction and transformation method is verified using the Multi-GNSS Experiment (MGEX) station data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1422-1432
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• 2011

Recently, wireless network has been playing an important role in communication system and the applications have become wider with its big technological leap. In defence sector, there are some attempts to use wireless networks to go beyond the wire system. Especially, most internal space of the warships have the wired communication system, which are complicated and inefficient. In this paper, we measure and make a channel model about the internal parts of the warship which contain compartments and corridors including many differences from general indoor environment for establishing wireless networks in warship's internal space. In the unique environment made of metal, we measure 2.4GHz signals using continuous wave(CW) and analysis the environment to present indoor path-loss model for comparing with results from the ray-tracing tool. Moreover, we draw the conclusion that the environment of warships has a wide difference from conventional environments and put the results to practical use in warship's internal space.

• Journal of Energy Engineering
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• v.25 no.3
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• pp.114-129
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• 2016

Since the release of mid-term domestic GHG goals until 2020, in 2009, some various GHG reduction policies have been proposed to reduce the emission rate about 30% compared to BAU scenario. There are two types of modeling approaches for identifying options required to meet greenhouse gas (GHG) abatement targets and assessing their economic impacts: top-down and bottom-up models. Examples of the bottom-up optimization models include MARKAL, MESSAGE, LEAP, and AIM, all of which are developed based on linear programming (LP) with a few differences in user interface and database utilization. The bottom-up model for electric sector requires demand management, regeneration energy mix, fuel conversation, etc., thus it has a very complex aspect to estimate some various policies. In this paper, we suggest a bottom-up BAU model for electric sector and how we can build it through step-by-step procedures such that includes load region, hydro-dam and pumping storage.