• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권4호
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• pp.491-508
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• 2010

In peer-to-peer (P2P) on-demand streaming networks, the alleviation of server load depends on reciprocal stream sharing among peers. In general, on-demand video services enable clients to watch videos from beginning to end. As long as clients are able to buffer the initial part of the video they are watching, on-demand service can provide access to the video to the next clients who request to watch it. Therefore, the key challenge is how to keep the initial part of a video in a peer's buffer for as long as possible, and thus maximize the availability of a video for stream relay. In addition, to address the issues of delivering data on lossy network and providing scalable quality of services for clients, the adoption of multiple description coding (MDC) has been proven as a feasible resolution by much research work. In this paper, we propose a novel caching scheme for P2P on-demand streaming, called Dynamic Buffering. The proposed Dynamic Buffering relies on the feature of MDC to gradually reduce the number of cached descriptions held in a client's buffers, once the buffer is full. Preserving as many initial parts of descriptions in the buffer as possible, instead of losing them all at one time, effectively extends peers’ service time. In addition, this study proposes a description distribution balancing scheme to further improve the use of resources. Simulation experiments show that Dynamic Buffering can make efficient use of cache space, reduce server bandwidth consumption, and increase the number of peers being served.

• 농촌계획
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• 제26권2호
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• pp.117-126
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• 2020

In this study, demands of smart technology development were analyzed for rural village communities. Questionnaire items were derived by grasping the current status of information and communication technology. 49 villages in 8 regions were selected and surveys and statistical analysis were conducted. The main results of the study are as follows. First, 92% of community leaders use smartphones, search for information (38%), communicate with the Internet (36%) using smartphones, use KakaoTalk (31%), and Facebook (24%). Second, in the rural and urban exchange activities, promote support information service (51%) and promote method suggestion service (48.5%) showed that the demand for services in promote field was high. It is linked to the creation of economic opportunities. Third, in the income and production activities, demand for distribution services technology (39.3%) was high in the field of production and distribution, and cold chains that help maintain freshness until food, such as meat, fish, and vegetables are delivered to consumers when agricultural products are distributed. The constant temperature control system needs to be actively introduced. Fourth, autonomy activities showed the highest demand for air conditioning and control systems (34.2%) of community building, and the lowest demand for electronic voting (9.4%) and videoconferencing (9.4%) services. Lastly, in the general activity area of the community, the demand for technology of emergency services (37.1%) and health self-diagnosis service (35.4%), which are technologies in the welfare sector, ranked first and second respectively.

• 대한한의학회지
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• 제26권2호
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• pp.85-94
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• 2005

Objectives: This study was carried out to estimate the demand for clinical trials and contribute to the consolidation of function and role in the clinical trial centers of oriental medicine. Methods: A survey of the demand was made of 379 faculties of oriental medicine in 11 oriental medical colleges throughout the country using two?part investigations by e-mail questionnaire over 1 month. The final data from 56 faculties were analyzed. Results: Clinical trials of oriental medicine have been continuously increasing. Furthermore, the demand and necessity for clinical trials of oriental medicine have also been continuously enhanced. Although there were arguments for and against the establishment of a clinical trial center for oriental medicine, the demand and necessity for the establishment was the overall consensus. Concerning objections, a high intention of use was observed. Conclusions: These results imply that the demand for clinical trials will increase remarkably through the establishment of a clinical trial center for oriental medicine. Further study is needed about the demand for such a center.

• 대한임베디드공학회논문지
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• 제5권4호
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• pp.225-233
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• 2010

In this paper, we try to improve the performance of the demand paging loader suggested to use the demand paging way that is not based on operating system. The demand paging switching strategy used in the existing operating system can know the recently used pages by running multi-processing. Then, based on it, some page switching strategies have been made for the recently used pages or the frequently demanded pages. However, the strategies based on operating system cannot be applied in single processing that is not based on operating system because any context switching never occur on the single processing. So, this paper is trying to suggest the demand paging switching strategies that can be applied in paging loader running in single process. In the Return-Prediction-Algorithm, we saw the improved performance in the program that the function call occurred frequently in a long distance. And then, in the Most-Frequently-Used-Page-Remain-Algorithm, we saw the improved performance in the program that the references frequently occurred for the particular pages. Likewise, it had an enormous effect on keeping the memory reduction performance by the demand paging and reducing the running time delay at the same time.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권3호
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• pp.262-276
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• 2016

Generally, the Safety Integrity Level (SIL) of a subsea Blowout Preventer (BOP) is evaluated by determining the Probability of Failure on Demand (PFD), a low demand mode evaluation indicator. However, some SIL results are above the PFD's effective area despite the subsea BOP's demand rate being within the PFD's effective range. Determining a Hazardous Event Frequency (HEF) that can cover all demand rates could be useful when establishing the effective BOP SIL. This study focused on subsea BOP functions that follow guideline 070 of the Norwegian Oil and Gas. Events that control subsea well kicks are defined. The HEF of each BOP function is analyzed and compared with the PFD by investigating the frequency for each event and the demand rate for the components. In addition, risk control options related to PFD and HEF improvements are compared, and the effectiveness of HEF as a SIL verification for subsea BOP is assessed.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.436-445
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• 2013

The use of a demand response controller is necessary for electric devices to effectively respond to time varying price signals and to achieve the benefits of cost reduction. This paper describes a new formulation with the form of constrained optimization for designing an optimal demand response controller. It is demonstrated that constrained optimization is a better approach for the demand response controller, in terms of the ambiguity of device operation and the practicality of implementation of the optimal control law. This paper also proposes a design scheme to construct a demand response controller that is useful when a system controller is already adapted or optimized for the system. The design separates the demand response function from the original system control function while leaving the system control law unchanged. The proposed formulation is simulated and compared to the system with simple dynamics. The effects of the constraints, the system characteristics and the electricity price are examined further.

• Earthquakes and Structures
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• 제26권2호
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• pp.117-130
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• 2024

Probabilistic model of seismic demand is the main tool used for seismic demand estimation, which is a fundamental component of the new performance-based design method. This model seeks to mathematically relate the seismic demand parameter and the ground motion intensity measure. This study is intended to use Bayesian analysis to evaluate the accuracy of the seismic demand estimation of Steel moment resisting frames (SMRFs) through a completely Bayesian method in statistical calculations. In this study, two types of intensity measures (earthquake intensity-related indices such as magnitude and distance and intensity indices related to ground motion and spectral response including peak ground acceleration (PGA) and spectral acceleration (SA)) have been used to form the models. In addition, an extensive database consisting of sixty accelerograms was used for time-series analysis, and the target structures included five SMRFs of three, six, nine, twelve and fifteen stories. The results of this study showed that for low-rise frames, first mode spectral acceleration index is sufficient to accurately estimate demand. However, for high-rise frames, two parameters should be used to increase the accuracy. In addition, adding the product of the square of earthquake magnitude multiplied by distance to the model can significantly increase the accuracy of seismic demand estimation.

• 한국분말재료학회지
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• 제22권3호
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• pp.187-196
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• 2015

With the stabilization of Korea's industrialization, it has become interested in the efficient use of rare metals, climate change and industrial environment and safety etc. It is thus making efforts to implement economic policies that address such issues. Therefore it is necessary to understand the demand, supply and use of metal materials. Since 2010, the Korean government has developed the integrated material flow methodology and has been trying to examine the demand, supply and use of metal materials. In 2013, the Korean government surveyed the material flow of chromium. Material flow analysis and environment emission of chromium were investigated 8 steps; (1) raw material, (2) first process, (3) Intermediate product, (4) End product, (5) Use/accumulation, (6) Collection, (7) Recycling, (8) Disposal. Chromium was used for stainless steel, alloy steel, coated sheets, refractory material and coating materials. Recycling was done mainly in use of stainless steel scrap. To ensure efficient use of chromium, process improvement is required to reduce the scrap in the intermediate product stage. In the process of producing of the products using chromium, it was confirmed that chromium was exposed to the environment. It requires more attention and protection against environment emission of chromium.

• 자원환경지질
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• 제23권4호
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• pp.383-392
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• 1990

이 연구(硏究)에서는 경험적인 사용강도(便用强度) 방법(方法)과 파생수요(派生需要)의 경제적이론을 초월대수(超越代數) 수요(需要) 모델을 사용(使用)하여 결합하였다. 첫번째 단계로서 한 인구당 GDP와 사용강도(使用强度)의 실험적인 패턴인 비대칭(非對稱) 생명곡선(生命曲線)을 고려하였으며, 두번째 단계로서는 이러한 비대칭(非對稱) 생명곡선(生命曲線)이 수학적으로 단순한 초월대수(超越代數) 사용강도(使用强度) 모델로 바꿀수 있다는 것을 보여 주었으며, 마지막 단계로서 전통적인 수요이론(需要理論)이 가격(價格), 대체효과(代替效果), 기술(技術)의 변화(變化)를 포함한다는 것에 근거하여 초월(超越) 대수(代數) 수요(需要) 모델을 연장한 결과 전통적인 수요(需要)모델이나 사용강도(使用强度) 모델보다 더 정확하게 광물자원(鑛物資源) 수요(需要)를 예측(豫測)하였으며 사용강도(使用强度) 방법(方法)으로서도 자원(資源)의 수요(需要)를 예측(豫測)할 수 있음을 보여주었다.

• 한국주거학회논문집
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• 제14권1호
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• pp.1-10
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• 2003

The purpose of this study is to analyze patterns of space use and housing preferences to be used in the housing plan for students. Data was collected through questionnaire surveys from local university students living apart from their family. We collected 272 samples and analyzed them using SPSSwin program. The results are as follows; 1) The average hours of staying at the housing for student are 5 hours and 30 minutes(except sleeping time). Most of the time was used for ‘hobby’ and ‘study\ulcorner computer works’. The most of the students had ‘a meal per day’ at their housing. 2) The most preferred housing type by the students is ‘studio apartment’ and the next preferred is ‘apartment’. The highly demanded facility is ‘laundry’ and the next comes ‘kitchen’. 3) Those who spend more time in their housing than average show higher demand in ‘kitchen’ and ‘balcony’. Those who spend less time in their housing show higher demand in ‘storage’.