• 한국전산유체공학회지
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• 제12권1호
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• pp.28-34
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• 2007

This study evaluates the performance of the packed bed scrubber and proposes the optimization of spray system for improvements of collection efficiency. The packed bed scrubber is used primarily in the semiconductor manufacturing process. The mean diameter of entering solid particles in scrubber is the submicron. The impaction between water droplets and solid particles is an important factor in removing the solid particles. Thus, the coverage area of spray system influences on the collection efficiency. The collection efficiency of a single droplet is calculated through the mathematical model and numerical calculations are performed for coverage area for each nozzle type (Droplet diameters: 500, 319.5, $289.5{\mu}m$) and injected directions (0, 15, $30^{\circ}$). In case of nozzle type 3, the collection efficiency of a single droplet is highest but the collection efficiency of spray system has lowest value because the ratio of flow rate between the gas and water is below 0.1. The results show the coverage area ratio is about 85% in the case of nozzle type 3 and downward sirection $15^{\circ}$. It was shown that a coverage area increase by two times than an existing spray system. In simulation of demister, collection efficiency by demister is predicted about 80% and the pressure drop in demister is below 3.5 Pa.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2534-2544
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• 2024

This paper proposes a flooding safety system (FSS) and its operation strategy that can provide long-term safety and effective maintenance for modules of small modular reactor (SMR) and metal containment maintained at dried environment during normal operation. During hypothesized accidents, the FSS re-collects the evaporated steam into the common pool by the condenser installed above the common water pool and provides an emergency coolant for the cavities and auxiliary pools. This study suggested that the condensate re-collection strategy using the FSS can effectively delay the depletion of available water in response to the accidents. Without recollection, the achievable grace periods ranged from 44 to 1507 days for six-module and one-module accidents, respectively. However, with a full re-collection (ratio = 1.0), the time to total depletion of emergency coolant was estimated indefinite. Even with a partial re-collection ratio of 0.3, a grace period of 83.5 days could be ensured for a six-module transient. This study reported the effectiveness of condensate re-collection and the FSS as an innovative safety management strategy and system. Employing a condensate re-collection strategy with a high re-collection ratio can enhance the long-term safety and effective convenience of SMR operations and maintenance.

• 조명전기설비학회논문지
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• 제25권7호
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• pp.83-91
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• 2011

Even if smoke, fumes, mist or dust particles are removed by electrostatic precipitators (ESPs), the occurrence of ozone, which is harmful to human body, has to be severely restricted in the indoor environments of hospitals, offices, and workshops. Therefore, the two-stage ESP generating positive corona at the ionizer is typically used because it creates less ozone than the two-stage ESP generating negative corona at the ionizer. In order to predict the collection performance and the optimal design of the two-stage ESP applied to positive high-voltage, particle concentration is experimentally investigated in this paper. In addition, particle motion within the collector section is also numerically analyzed. The positive corona discharge current of the ionizer is found to be affected by the applied voltage in the collector section but less so by the particle concentration. Particle concentration shows a minimum near the high voltage electrode of the collector section. The minimum value of the collection efficiency is almost proportional to gas velocity. When the collector length decreases, the minimum value of the collection efficiency increases. Charged particles entering the collector region are linearly deflected towards the grounded plate by an electric field. From the above experimental and numerical results, two empirical equations on the concentration ratio and the collection efficiency are derived, and are in good agreement with the experimental data.

• 정보관리학회지
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• 제35권1호
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• pp.205-229
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• 2018

본 연구는 국내 대학도서관 서양서 장서 개발의 변화를 살펴보기 위해 2003년과 2013년에 출판된 서양서 소장 실태를 KERIS 종합목록을 통해 분석하였다. 이를 위해 새로운 장서 지표로 소장 h-지수, 장서 고유성 지수, 그리고 공통장서 확보율을 제안하고 기본 지표인 종수 및 책수, 그리고 종당 책수와 함께 활용하였다. 분석 결과 2003년에 비해서 2013년에 출판된 서양서의 전체 소장 종수는 16.1% 감소하고 소장 책수는 42.2% 감소하여 소장 책수가 더 크게 감소하였다. 여러 도서관이 공통적으로 소장하는 공통 장서, 또는 기본 장서의 규모를 나타내는 공통장서 확보율은 줄어들었고, 장서고유성은 증가하였다. DDC 주류 중에서는 컴퓨터 관련 도서가 급감한 0XX(총류) 분야의 감소율이 가장 컸다. 도서관별 장서량 측면에서는 2003년에 비해서 2013년 출판도서의 경우에 상위 도서관이 더욱 과점하는 빈익빈 부익부 현상이 심화되었다.

• 한국도서관정보학회지
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• 제48권1호
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• pp.21-42
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• 2017

이 연구는 학교도서관의 장서관리 현황을 파악하기 위해 전국의 154개교를 대상으로 설문조사를 실시하여 분석한 결과이다. 설문지는 학교도서관의 장서현황, 이용현황, 장서관리 체제의 3개 영역에 걸친 총 12개의 조사내용으로 구성되었다. 분석결과 도출된 주요 내용을 종합하면 다음과 같다. 첫째, 자료현황에서 2015년 기준 학생 1명당 단행본 수는 전문단체인 한국도서관협회기준과 비교하여 초등학교와 중학교는 기준을 초과하였으나, 고등학교는 기준에 미치지 못하였다. 입수자료의 주제별 비율은 문학이 압도적으로 높았으며, 다음 주제로 사회과학과 역사의 비율이 높게 나타났다. 둘째, 이용현황에서 학교급별 대출현황은 학생, 교사, 학부모 모두 초등학교에서 높게 나타났다. 그리고 2013년부터 2015년까지 한 번도 대출된 적이 없는 자료는 전체 장서의 64.6%로 나타났다. 셋째, 장서관리 체제에서 전체 154개교 중 114개교(74%)가 자체의 장서관리 정책서를 보유하고 있고, 이들 모든 학교는 연간 1회 이상의 장서점검 및 평가를 실시하였다. 그리고 대부분의 학교는 자체의 학교도서관운영위원회를 구성하고 있으며, 이들은 연 중 2~3회의 회의를 개최하는 것으로 나타났다. 그리고 학교도서관운영위원회는 학교도서관 현안문제에 대한 대화와 소통의 장으로, 그리고 장서개발, 운영지원, 홍보에서 중요한 역할을 수행하는 것으로 조사되었다.

• Mycobiology
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• 제44권4호
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• pp.269-276
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• 2016

Aspergillus luchuensis is known as an industrially important fungal species used for making fermented foods such as awamori and shochu in Japan, makgeolli and Meju in Korea, and Pu-erh tea in China. Nonetheless, this species has not yet been widely studied regarding mating-type genes. In this study, we examined the MAT1-1 and MAT1-2 gene ratio in black koji molds (A. luchuensis, Aspergillus niger, and Aspergillus tubingensis) and in Aspergillus welwitschiae isolated from Meju, a fermented soybean starting material for traditional soy sauce and soybean paste in Korea. The number of strains with the MAT1-1 locus was 2 of 23 (A. luchuensis), 6 of 13 (A. tubingensis), 21 of 28 (A. niger), and 5 of 10 (A. welwitschiae). Fungal species A. tubingensis and A. welwitschiae showed a 1 : 1 ratio of MAT1-1 and MAT1-2 mating-type loci. In contrast, A. luchuensis revealed predominance of MAT1-2 (91.3%) and A. niger of MAT1-1 (75%). We isolated and identified 2 A. luchuensis MAT1-1 strains from Meju, although all strains for making shochu in Japan are of the MAT1-2 type. These strains may be a good resource for breeding of A. luchuensis to be used in the Asian fermented-food industry.

• 한국정보과학회논문지:시스템및이론
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• 제36권5호
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• pp.422-428
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• 2009

플래시 메모리는 부피가 작고, 가볍고, 소비전력이 낮으며 입출력이 빨라 최근 소형기기의 저장 장치로 널리 사용이 되고 있다. 그러나 플래시 메모리는 지움 연산을 수반하는 가비지 컬렉션을 수행해야 한다. 지움 연산은 속도가 느리고, 각 블록마다 지움 연산 횟수가 제한이 있다. 따라서 본 논문에서는 지움 연산 횟수와 각 블록의 지움 횟수 편차를 줄이는데 초점을 맞춘 균등화 정책을 제안한다. 따라서 플래시 메모리의 페이지 사용률에 기반을 둔 두 가지 가비지 컬렉션 수행 모드를 정의하고 그리고 각 모드에 대해 다른 지움 비용을 계산하여 전체 지움 연산 횟수와 각 블록의 지움 횟수 편차를 최소화하는 가비지 컬렉션 기법을 제안한다. 추가로 가비지 컬렉션 연산 시간을 최소화하기 위해 그룹 관리 기법을 제안해 보다 빠른 수행 시간을 가질 수 있도록 한다. 실험 결과 제안하는 정책은 기존의 Greedy 와 CAT 기법의 장점들을 동시에 나타내었고, 지움 횟수 편차를 평균 85% 감소 시켰고 가비지 컬렉션 수행 시간을 최대 6% 단축 시켰다

• 한국입자에어로졸학회지
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• 제19권3호
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• pp.77-87
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• 2023

We present the development of a wetcyclone sampler designed for the sampling of airborne bacteria. The wetcyclone design involves a combination of two traditional cyclone shapes and computational fluid dynamics (CFD) analysis to validate its effectiveness in terms of pressure drop and collection efficiency. The wetcyclone exhibits a collection efficiency of over 90% for bacteria, specifically targeting Staphylococcus aureus. Additionally, the wetcyclone enables continuous bioaerosol sampling using a liquid medium (deionized water), demonstrating a concentration ratio exceeding >105 and a stable microbial recovery rate of 81.9%. The application of real-time quantitative polymerase chain reaction (qPCR) and the colony counting method ensures precise measurement of the concentration ratio and microbial recovery rate.

• 환경정책연구
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• 제2권1호
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• pp.51-75
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• 2003

The objective of this study is to analyze the problems of disposal and collection, including administrative management of agricultural PE waste and suggest effective management measurements. Information regarding problems of agricultural PE waste management were collected from field survey of farmers, regional governments and officials. On the national level, the low ratio of collection for optimal treatment of agricultural PE waste is a critical problem. , the negative discharging behavior of farmers, an illegal incineration and landfill of farmers and a lack of education and extension etc. An ambiguity of the management principle to agricultural PE waste, the differences in management among the regional governments, a lack of will of the regional governments and officials to realize SARD and lack of education and extension etc. are some of the problems in administrative management of agricultural PE waste collection. The major suggestions of this study are as follows : (1) to strengthen education and extension, (2) to adopt an improved economic incentive system and strong, lawful regulation simultaneously, (3) to use temporang collection and permanent collection site, and (4) to organize "OTC(Optimal Treatment Conference)" composed of farmers, regional cooperative, PE producers etc. for operating an effective management system.

• 한국작물학회지
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• 제43권4호
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• pp.269-272
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• 1998

Characteristics of seed and plant growth of the nine local collections of the medicinal plant, Agastache rugosa were evaluated. Seed size of the collection from Garyungsan was larger than the others. Seeds of Damyang collection were the smallest in size. Seeds of the collections were mostly oval shaped. There were no differences between brown and black seed coat color groups in seed width, ratio of seed length to seed width and 1,000 seed weight. Stem lengths of Garyungsan and Bongpyung collections were 99.9 and 95.6 cm, respectively, and were longer than Damyang and Jindo collections. Garyungsan collection had long leaf shape. Leaf size was the smallest for Damyang collection, but was the largest for Bongpyung collection. Inflorescence length of Mokpo collection (15.6 cm) was longer than the average over all collections (12.3 cm). Damyang collection was the shortest (10.1 cm) in inflorescence. Top dry weight of each collection from Soonchun, Bongpyung, Mokpo, Jindo, and Gurye was greater than the average over all collections (20.38 g/plant). Jinju and Damyang collections had less top dry matter than others. There was no difference in the growth traits examined between brown and black seed coat groups. The brown seed group was greater in leaf weight than the black seed group. However, these two groups were not different in stem and inflorescence weight. Collections of A. rugosa from Bongpyung, Soonchun, and Mokpo were promising for commercial cultivation because of their great top dry weight, especially in leaf and inflorescence.