• Journal of the Korean Association of Geographic Information Studies
• /
• v.20 no.3
• /
• pp.12-26
• /
• 2017

The objective of this study was to develop a runoff analysis system of the Nakdong River watershed using the GRM (Grid-based Rainfall-runoff Model), a physically-based distributed rainfall-runoff model, and to assess the system run time performance according to Microsoft Azure VM (Virtual Machine) settings. Nakdong River watershed was divided into 20 sub-watersheds, and GRM model was constructed for each subwatershed. Runoff analysis of each watershed was calculated in separated CPU process that maintained the upstream and downstream topology. MoLIT (Ministry of Land, Infrastructure and Transport) real-time radar rainfall and dam discharge data were applied to the analysis. Runoff analysis system was run in Azure environment, and simulation results were displayed through web page. Based on this study, the Nakdong River real-time runoff analysis system, which consisted of a real-time data server, calculation node (Azure), and user PC, could be developed. The system performance was more dependent on the CPU than RAM. Disk I/O and calculation bottlenecks could be resolved by distributing disk I/O and calculation processes, respectively, and simulation runtime could thereby be decreased. The study results could be referenced to construct a large watershed runoff analysis system using a distributed model with high resolution spatial and hydrological data.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11a
• /
• pp.754-756
• /
• 2005

현대는 실제와 같은 환경을 재현할 수 있도록 제작된 시뮬레이터를 사용하여 실제 훈련을 대체하고 있다. 그러나 많은 사용자들은 이미 개발된 이종의 시뮬레이터들을 하나로 묶어 연동할 필요성을 느끼게 되었고, 이에 따라 다양한 형태의 상호작용이 수반되는 시뮬레이션에 대한 요구를 만족하는 대규모 분산가상환경(large-scaled distributed virtual environment)을 개발하려는 움직임이 크게 늘게 되었다. 이러한 요구를 바탕으로 등장한 것들 중 하나가 HLA이다. High Level Architecture (HLA)는 미국방성에서 모델과 시뮬레이션에 공통의 구조와 인터페이스를 제공하기 위해 개발된 통합 구조이다. HLA는 분산 컴퓨팅 환경에서 각각의 시뮬레이터들이 정보를 교환 할 수 있게 해줌으로써 하나의 통합 시뮬레이션 시스템을 구축하게 해준다. HLA는 크게 Object Model Template (OMT)와 Run-Time Infrastructure (RTI)로 구성되어 있으며, 이를 통하여 공통된 구조와 상호 작용 환경을 제공한다. 각각의 시뮬레이터들은 RTI를 통하여 Federation에 참여하고 선별적으로 원하는 정보를 주고받으며 하나의 통합 시뮬레이션을 이루게 된다. 본 논문에서는 분산 컴퓨팅 환경에서 이기종의 3차원 영상 시뮬레이터들에 HLA 인터페이스를 삽입하고 3차원 영상 시뮬레이션에 적합하게 개발된 공통 구조인 FOM 제공하여 하나의 통합 가상훈련 시스템을 구축하였다. 이 시스템은 현재 KA-32 헬기 시뮬레이터 영상 프로그램 제작에 적용되어있다.

• Journal of Navigation and Port Research
• /
• v.44 no.5
• /
• pp.400-406
• /
• 2020

In this study, we first measured the malmquist productivity index by DEA among the Korean public firms. Second, there are 12 public corporations whose productivity (MPI) has decreased compared to 2014. This is mainly because of a decrease in productivity, as well as a decrease in the technical efficiency change index (TECI), impacted by the internal environment, and the increase in productivity because of an increase in the technology change index (TCI) impacted by the external environment. Finally, the analysis of the impact on the management assessment scores showed that the productivity (MPI), scale efficiency (CRS), size of sales, operating profitability, and total capital investment efficiency are significantly related (+), except for the asset turnover, which is a static financial ratio. Meanwhile, the management evaluation scores between the high-productivity public corporations and low-performing public corporations were significantly discriminating. Thus, it is confirmed that the nation's state-run companies must manage their MPIs in a time series to score high in management evaluation.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.6
• /
• pp.2456-2467
• /
• 2018

Wireless multimedia sensor networks (WMSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. The end-to-end delay is very critical metric for QoS guarantees in WMSNs. In WMSNs, due to the transmission errors incurred over wireless channels, it is difficult to obtain reliable delivery of data in conjunction with low end-to-end delay. In order to improve the end-to-end delay performance, the system has to drop few packets during network congestion. In this article, our proposal is based on optimization of end-to end delay for WMSNs. We optimize end-to-end delay constraint by assuming that each packet is allowed fixed number of retransmissions. To optimize the end-to-end delay, first, we compute the performance measures of the system, such as end-to-end delay and reliability for different network topologies (e.g., linear topology, tree topology) and against different choices of system parameters (e.g., data rate, number of nodes, number of retransmissions). Second, we study the impact of the end-to-end delay and packet delivery ratio on indoor and outdoor environments in WMSNs. All scenarios are simulated with multiple run-times by using network simulator-2 (NS-2) and results are evaluated and discussed.

• Korean Journal of Computational Design and Engineering
• /
• v.17 no.4
• /
• pp.274-281
• /
• 2012

This paper proposed a control simulation method for design and verification of the transport system in an automobile assembly line based on digital manufacturing system. The design of the transport system involves two major activities: mechanical design (device specification) and electrical design (device behavior and system control). Conventionally, the simulation and emulation system of the transport system focuses on the abstract level, which mainly deals with design verification, alternative comparison, and system diagnosis. Although it can provide overall system visibility in monitoring how well it works in the process and view, its simulation models are not sufficiently realistic to be used for a detailed design or for implementation purposes. In this paper, a digital simulation model for a transport system in an automotive assembly line is constructed by adapting a digital manufacturing methodology. We use the concept of the "Virtual Probe", which transport a carrier instead of the belt of the conveyor. In conclusion, the proposed method is valuable in the process of test run in the shop floor. This method would reduce the time and effort for validating the manufacturing system and improve the productivity and integrity of the control program.

• Korean Institute of Interior Design Journal
• /
• v.14 no.4 s.51
• /
• pp.114-121
• /
• 2005

Recently, it is not too much to say that the world of hospital architecture in Korea is in a time of transition that undergo big changes. Each hospital .pursues their transformation not only for patiences' changing demands on medical services but to cope with rapid environmental changes that pouring like boundless competition, opening tendency and to get an advantage of competition to attract patiences with other hospitals. It is because national expectations and standards on medical services have risen and they are not satisfied with hospitals that run for doctors and medical care that served technically any more. With rising interests in health, it is emphasized not the functions of hospitals to prevent diseases but the purpose of treatment and securing other facilities according to rising economical incomes except medical facilities.

• Nuclear Engineering and Technology
• /
• v.54 no.10
• /
• pp.3682-3694
• /
• 2022

The expansion of a country's ecological footprint generates resources for economic development. China's import bill and carbon footprint can be reduced by investing in green transportation and energy technologies. A sustainable environment depends on the cessation of climate change; the current study investigates nuclear energy efficiency, economic complexity, air transportation, and industrial improvement for reducing environmental footprint. Using data spanning the years 1983-2016, the dynamic autoregressive distributed lag simulation method has demonstrated the short- and long-term variability in the impact of regressors on the ecological footprint. The study findings revealed that economic complexity in China had been found to have a statistically significant impact on the country's ecological footprint. Moreover, the industrial improvement process is helpful for the ecological footprint in China. In the short term, air travel has a negative impact on the ecological footprint, but this effect diminishes over time. Additionally, energy innovation is negative and substantial both in the short and long run, thus demonstrating its positive role in reducing the ecological footprint. Policy implications can be extracted from a wide range of issues, including economic complexity, industrial improvement, air transportation, energy innovation, and ecological impact to achieve sustainable goals.

• The KIPS Transactions:PartC
• /
• v.10C no.5
• /
• pp.575-584
• /
• 2003

Due to hardware resource limit and system incompatibility of the mobile device, and low bandwidth of wireless communication, there are a few difficulties in introducing the digital contract system based on wired communication to M-Commerce. To get over the difficulties, this paper defines a digital contract based upon XML and then addresses the design and implementation of M-XContract, a digital contract system for the mobile environment. M-XContract system has been constructed with the digital contract server, M-ESign module which contracts with the customer on the PDA and transfers the contract digitally signed to the server, M-EDecoder module which shows the contract to the customer from the server, and X-Auth which is a contract authoring tool. To evaluate the run-time performance of the M-XContract, we measured the digital signature generation time and transfer time to the server. The evaluation results show that the M-Xcontract is an efficient model for the mobile contract system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.6
• /
• pp.293-299
• /
• 2015

In Korea, it is the law that an apartment building which consists of over 100 households must have a ventilation system installed, either natural or mechanical. The heat recovery ventilator (HRV) is great way to reduce energy consumption. In this research we confirmed that based on site's construction plan and existing diffuser form, performed purpose CFD which simulates operation in temperatures below $-5^{\circ}C$ to circumstances of installation of an HRV in an apartment. As a result of this research we found that when the diffuser's aperture area was adjusted, the distribution of air temperature and residence time of air was more equally distributed and air temperature was higher, compared to when the diffuser has an identical aperture area. We also found that we are able to increase even more air temperature and air distribution of air temperature and residence time of air was even more equally distributed when run in parallel with a splitter damper.

• Journal of KIISE:Computing Practices and Letters
• /
• v.11 no.6
• /
• pp.465-476
• /
• 2005

In this paper, we propose a new dynamic reconfiguration method using application-level checkpointing in a grid computing environment with Cactus and Globus. The existing dynamic reconfiguration methods have been dependent on a specific hardware and operating system. But the proposed method performs a dynamic reconfiguration without supporting specific hardwares and operating systems and, an application is programmed without considering a dynamic reconfiguration. In the proposed method, the job starts with an initial configuration of Computing resources and the job restarts including new resources dynamically found at run-time. The proposed method determines whether to include the newly found idle sites by considering processor performance and available memory of the sites. Our method writes the intermediate results of the job on the disks using system-independent application-level checkpointing for real-time visualization during the job runs. After reconfiguring idle sites and idle processors newly found, the job resumes using checkpointing files. The proposed dynamic reconfiguration method is proved to be valid by decreasing total execution time In K*Grid.