• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.92-92
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• 2012

최근 반도체 산업 경기의 활황에 따라 반도체 생산 설비 또한 꾸준히 증설되어가는 추세이며 고진공 펌프의 수요 또한 점차적으로 증가하고 있는 현실이다. 하지만, 국내 기술의 부족으로 고진공 펌프는 대부분 해외로부터의 수입에 의존하고 있다. 반도체 생산 설비는 매우 보수적인 설비로써 새로 개발되는 고진공 펌프가 반도체 생산 설비에 사용되기 위해서는 원천기술, 상품화 기술 및 신뢰성 기술을 확보해야 하며, 특히 한미/한일/한-EU FTA 등에 대비하여 제품의 국산화가 시급한 실정이다. 이에 고진공펌프의 수입이 급증할 것으로 예상되어 국내 진공업체에서도 크라이오펌프의 개발이 진행되고 있다. 본 연구에서는 지식경제부 제조기반 산업원천기술개발사업에 주관기관으로 수행하여 한국기계연구원 및 한국원자력연구원과 급속재생형 저진동 크라이오펌프의 기술 개발을 통해 전량 수입하는 크라이오펌프를 국산화를 도모 하고자 한다. 크라이오펌프의 주요 생산업체는 미국기업의 CTI사이며, 상품화 기술의 성능 확보를 위한 CTI사의 GM 극저온 냉동기와 현재 개발 및 상용화 준비를 하는 극저온 맥동관 냉동기에 대해 성능평가 지표를 제시하며, 신뢰성 확보를 위한 한국과학기술원 나노종합팹센터의 스퍼터 공정장비에 대한 CTI사 크라이오펌프와 상용화를 위한 개발품의 공정 현장시험에 대해 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.149-156
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• 2017

Nuclear fuel requires high reliability and safety and therefore contains debris filtering devices to prevent failure-inducing debris from entering it. The debris filtering performance of nuclear fuel is one of the most important factors for fuel integrity. Therefore, the performance must be evaluated and the measurement must be reasonable. In this study, a calculation method of the comprehensive filtering efficiency using the weighted mean was proposed to establish a standard filtering efficiency index. To confirm the suitability of the proposed method, representative debris specimens were selected and the filtering efficiency with the weighted mean was compared with the efficiency of the arithmetic mean. The weighting factor of the weighted mean was introduced to produce a fair evaluation. In addition, the analysis of the debris filtering mechanism was performed according to the size of debris specimens, and the main dimensions of the filtering feature for commercial nuclear fuel.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.175-196
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• 2004

This study focuses on improving the performance of freeway incident detection by introducing some new measures to reduce false alarms in developing a new incident detection model. The model consists of the 5 major components through which a series of decision makings in determining the given traffic flow condition are made. The decision making process was designed such that the causes of traffic congestions can be accurately classified into several types including incidents and bottlenecks according to their unique characteristics. The model performance was tested and found to be compatible with that of the existing well-recognized models in terms of the detection rate and detection time. It should noted that the model produced much less false alarms than most of the existing models. The study results prove that the initial objective of the study was satisfied as it was an experimental trial to improve the false alarm rate for the incident detection model to be more pactically usable for traffic management purposes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.13-23
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• 2016

Many traffic centers are highly hesitant in employing existing Automatic Incident Detection Algorithms due to high false alarm rate, low detection rate, and enormous effort taken in maintaining algorithm parameters, together with complex algorithm structure and filtering/smoothing process. Concerns grow over the situation particularly in Freeway Incident Management Area This study proposes a new algorithm and introduces a novel concept, the Displaced Flow Index (DiFI) which is similar to a product of relative speed and relative occupancy for every execution period. The algorithm structure is very simple, also easy to understand with minimum parameters, and could use raw data without any additional pre-processing. To evaluate the performance of the DiFI algorithm, validation test on the algorithm has been conducted using detector data taken from Naebu Expressway in Seoul and following transferability tests with Gyeongbu Expressway detector data. Performance test has utilized many indices such as DR, FAR, MTTD (Mean Time To Detect), CR (Classification Rate), CI (Composite Index) and PI (Performance Index). It was found that the DR is up to 100%, the MTTD is a little over 1.0 minutes, and the FAR is as low as 2.99%. This newly designed algorithm seems promising and outperformed SAO and most popular AIDAs such as APID and DELOS, and showed the best performance in every category.

• The Journal of the Acoustical Society of Korea
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• v.42 no.2
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• pp.133-142
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• 2023

The office environment is changing according to work types, Information Technology (IT) advancements, and the Coronavirus disease (COVID)-19 situation. In order for office space users to perform their tasks comfortably and efficiently, it is necessary to secure individual privacy as well as easy communication among members. In Korea, the demand for improving the acoustic performance of office spaces is also increasing, but the related performance criteria and guidelines have not been established. In this study, standardization of office space acoustic performance measurement and evaluation methods and European countries' acoustic performance criteria were compared and reviewed. It is proposed to comprehensively review international standardization trends and acoustic performance standards in each country and to establish and utilize criteria for evaluating the acoustic performance and satisfaction of office spaces in Korea through our survey. Considering the international standardization direction and compatibility with communication and Public Address (PA) systems, it is appropriate to establish criteria using the speech transmission index or Speech Transmission Index (STI) application index. This criterion will be highly utilizable and compatible. In addition, since the office furniture industry is interested in improving the acoustic performance of office space, it is necessary to establish a labelling system for speech level reduction of office furniture.

• The Korean Journal of Applied Statistics
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• v.37 no.1
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• pp.13-38
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• 2024

As economic uncertainties have increased recently due to COVID-19, there is a growing need to quickly grasp private consumption trends that directly reflect the economic situation of private economic entities. This study proposes a method of estimating private consumption in real-time by comprehensively utilizing big data as well as existing macroeconomic indicators. In particular, it is intended to improve the accuracy of private consumption estimation by comparing and analyzing various machine learning methods that are capable of fitting ultra-high-dimensional big data. As a result of the empirical analysis, it has been demonstrated that when the number of covariates including big data is large, variables can be selected in advance and used for model fit to improve private consumption prediction performance. In addition, as the inclusion of big data greatly improves the predictive performance of private consumption after COVID-19, the benefit of big data that reflects new information in a timely manner has been shown to increase when economic uncertainty is high.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.3
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• pp.165-174
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• 2015

Non-point source pollution associated with suspended solids in stormwater has been known to often adversely affect surface water ecosystems. Various methods of treating stormwater in the basin area before the stormwater reaches the receiving body of water have been developed. However, these treatment methods tend to be costly to install and also to maintain. In this study, an economical way of removing TSS (total suspended solids) from stormwater runoff with a fabric filter system was developed. Polyester was chosen as a fabric-filter material, because it was found to be economical in cost and relatively resistant to various chemicals. An experimental device was developed and used to determine filtration rates through polyester fabric samples of a series of several pore-opening sizes ($20{\mu}m$ to $94{\mu}m$) under a series of water-heads (0.25 to 1 m). It was found that the filtration rate increased as the size of water head increased. It was also found that the smaller the pore size of the fiber filter was, the higher the TSS removal efficiency was. However, the TSS removal efficiency was not found to be much different among the filters with different sizes of pore opening due to the fact that most mass of TSS was associated with large particles.

• Journal of Korea Soil Environment Society
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• v.3 no.2
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• pp.127-145
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• 1998

Unlike water or air quality standards that have been established by legislation using potential human health impact as the primary criterion, soil quality depends on the soils primary function and its relevant environmental factors, which is much more site- and soil specific. A properly characterized soil quality assessment system should serve as an indicator of the soil capacity to produce safe and nutritious food, to enhance human and animal health, and to overcome degrative processes. For our proposed example, a high quality soil with regard to maintaining an adequate soil productivity as a food production resources must accommodate soil and water properties, food chain, sustainability and utilization, environment, and profitability, that (i) facilitate water transfer and absorption, (ii) sustain plant growth, (iii) resist physical degradation of soil, (iv) produce a safe food resources, (v) cost-effective agricultural management. Possible soil quality indicators are identified at several levels within the framework for each of these functions. Each indicator is assigned a priority or weight that reflects its relative importance using a multi-objective approach based on principles of systems to be considered. To do this, individual scoring system is differentiated by the several levels from low to very high category or point scoring ranging from 0 to 10, And then weights are multiplied and products are summed to provide an overall soil quality rating based on several physical and chemical indicators. Tlne framework and procedure in developing the soil quality assessment are determined by using information collected from an alternative and conventional farm practices in the regions. The use of an expanded framework for assessing effects of other processes, management practices, or policy issues on soil quality is also considered. To develop one possible form for a soil quality index, we should permit coupling the soil characteristics with assessment system based on soil properties and incoming and resident chemicals. The purpose of this paper is to discuss approaches to defining and assessing soil quality and to suggest the factors to be considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.662-673
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• 2019

This paper investigates the most recent status of multi-GNSS, including technical features, types of ranging signals provided, and satellite constellation. Furthermore, a series of multi-GNSS positioning experiments in SPP mode were carried out to assess the achievable accuracy and continuity with an application to various positioning scenarios. A week of GNSS measurements each in 2018 and 2019 was acquired from the national geographical information institute and processed. The results show that a single GNSS-based scenario often encounters positioning blockage in the harsh operational environment, while multi-constellation cases are able to remedy this situation. The accuracy of multi-GNSS with a combination of GPS and Galileo is superior to that of other GNSS compositions due to the larger SISRE (Signal In Space Ranging Errors) of GLONASS and Beidou. Due to the different characteristics of GNSS SISRE, an issue has been raised to optimally integrate satellite measurements to maximize accuracy of multi-GNSS positioning.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.39-47
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• 2022

In this paper, we proposed a thickness measurement method of concrete slab using GPR, and the verification of the suggested algorithm was carried out through real-scale experiment. The thickness measurement algorithm developed in this study is to set the relative dielectric constant based on the unique shape of parabola, and time series data can be converted to thickness information. GPR scanning were conducted in four types of slab structure for noise reduction, including finishing mortar, autoclaved lightweight concrete, and noise damping layer. The thickness obtained by GPR was compared with Boring data, and the average error was 1.95 mm. In order to investigate the effect of finishing materials on the slab, additional three types of finishing materials were placed, and the following average error was 1.70 mm. In addition, sampling interval from device, the effect of radius on the shape of parabola, and Boring error were comprehensively discussed. Based on the experimental verification, GPR scanning and the suggested algorithm have a great potential that they can be applied to the thickness measurement of finishing mortar from concrete slab with high accuracy.