• 한국재료학회지
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• 제19권12호
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• pp.680-685
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• 2009

Using a polyurethane foam replica method, porous hydroxyapatite scaffolds (PHS) were fabricated using conventional and microwave sintering techniques. The microstructure and material properties of the PHS, such as pore size, grain size, relative density and compressive strength, were investigated at different sintering temperatures and holding times to determine the optimal sintering conditions. There were interconnected pores whose sizes ranged between about 300 ${\mu}m$ and 700 ${\mu}m$. At a conventional sintering temperature of 1100$^{\circ}C$, the scaffold had a porous microstructure, which became denser and saw the occurrence of grain growth when the temperature was increased up to 1300$^{\circ}C$. In the case of microwave sintering, even at low sintering temperature and short holding time the microstructure was much denser and had smaller grains. As the holding time of the microwave sintering was increased, higher densification was observed and also the relative density and compressive strength increased. The compressive strength values of PHS were 2.3MPa and 1.8MPa when conventional and microwave sintering was applied at 1300$^{\circ}C$, respectively.

• Nuclear Engineering and Technology
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• 제36권1호
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• pp.83-103
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• 2004

The methodological framework of the Level 2 PSA appears to be currently standardized in a formalized fashion, but there have been different opinions on the way the sources of uncertainty are characterized and treated. This is primarily because the Level 2 PSA deals with complex phenomenological processes that are deterministic in nature rather than random processes, and there are no probabilistic models characterizing them clearly. As a result, the probabilistic quantification of the Level 2 PSA CET / APET is often subjected to two sources of uncertainty: (a) incomplete modeling of accident pathways or different predictions for the behavior of phenomenological events and (b) expert-to-expert variation in estimating the occurrence probability of phenomenological events. While a clear definition of the two sources of uncertainty involved in the Level 2 PSA makes it possible to treat an uncertainty in a consistent manner, careless application of these different sources of uncertainty may produce different conclusions in the decision-making process. The primary purpose of this paper is to characterize typical sources of uncertainty that would often be addressed in the Level 2 PSA and to provide a formal guidance for quantifying their impacts on the PSA Level 2 risk results. An additional purpose of this paper is to give a formal approach on how to combine random uncertainties addressed in the Level 1 PSA with subjectivistic uncertainties addressed in the Level 2 PSA.

• 멤브레인
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• 제15권4호
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• pp.289-296
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• 2005

MBR 공정에서 가장 문제시되는 부분은 실제 공정상에서 막 표면에 오염이 발생하는 문제이다. 일반적으로 막 오염은 활성 슬러지들이 막 표면에 퇴적되어서 일어나며 이로 인해 심각한 투과 유량의 감소를 야기하게 된다. 본 연구에서는 막 오염 저항성이 뛰어난 나노 입자를 분리막 표면에 함침시켜 MBR 막을 제작하였으며 이 입자들은 막 표면에서 활성 슬러지들이 쉽게 달라 붙지 못하는 역할을 수행하게 된다. 즉, 뛰어난 투수량을 지닌 정밀여과막에 나노 입자를 첨가함으로서 실제 MBR 공정에서 막 오염을 저감시킴으로서 투수량을 보전할 수 있게 하였다. 이들을 이용하여 MBR 공정에서 막 오염이 휠씬 적게 일어나는 것을 확인하였으며 이를 바탕으로 현장에 적용하여 막 오염 저항성을 확인하였다.

• The Plant Pathology Journal
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• 제33권4호
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• pp.351-361
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• 2017

Bacterial canker is the largest limiting factor in the cultivation and production of kiwifruit worldwide. Typical symptoms comprise necrotic spots on leaves, canker and dieback on canes and trunks, twig wilting, and blossom necrosis. Pseudomonas syringae pv. actinidiae (Psa), which is the causal agent of kiwifruit bacterial canker, is divided into four biovars based on multilocus sequence analysis of different genes, additional PCR testing of pathogenic genes (argKtox cluster, cfl, and various effector genes), and biochemical and physiological characterization. Bacterial canker caused by Psa biovar 2 designated Psa2 was detected for the first time on the green-fleshed kiwifruit cultivar Hayward in 1988 and the yellow-fleshed kiwifruit cultivar Hort16A in 2006 in Korea. Psa biovar 3 designated Psa3, responsible for the current global pandemics of kiwifruit bacterial canker, began to appear in Korea in 2011 and caused tremendous economic losses by destroying many vines or orchards of yellow-fleshed kiwifruit cultivars in one or several growing seasons. Bacterial canker epidemics caused by both Psa2 and Psa3 are prevalent in Korea in recent years. In this review, we summarize the symptomatology, etiology, disease cycle, diagnosis, and epidemiology of kiwifruit bacterial canker in Korea.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.498-508
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• 2021

Micro reactors are increasingly being considered for utilization as distributed power sources. Hence, the probabilistic safety assessment (PSA) of a direct supercritical-CO₂-cooled fast reactor, called micro modular reactor (MMR), was performed in this study; this reactor was developed using innovative design concepts. It adopted a modular design and passive safety systems to minimize site constraints. As the MMR is in its conceptual design phase, design weaknesses and valuable safety insights could be identified during PSA. Level 1 internal event PSA was carried out involving literature survey, system characterization, identification of initiating events, transient analyses, development of event trees and fault trees, and quantification. The initiating events and scenarios significantly contributing to core damage frequency (CDF) were determined to identify design weaknesses in MMR. The most significant initiating event category contributing to CDF was the transients with the power conversion system initially available category, owing to its relatively high occurrence frequency. Further, an importance analysis revealed that the safety of MMR can be significantly improved by improving the reliability of reactor trip and passive decay heat removal system operation. The findings presented in this paper are expected to contribute toward future applications of PSA for assessing unconventional nuclear reactors in their conceptual design phases.

• 한국안전학회지
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• 제38권2호
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• pp.36-43
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• 2023

In this study, a four-point bending test was conducted to assess and detect the damage to reinforced concrete structures using the acoustic emission (AE) technique. Based on the crack investigation results, flexural failure was classified into four stages and compared with the characteristic analysis results of AE parameters. The parametric characterization indicated that the activity of the primary AE signal was high in the early stage, and that of the second signal increased after the flexural cracks stabilized. Because the secondary AE signal included noise generated by friction, parameter-based analysis for damage assessment was performed using the primary signal; the secondary signal was used as complement. The activity analyses of the primary and secondary signals effectively classified crack propagation; however, determining the macrocracks and yielding of reinforcing bars had certain limitations. Nevertheless, applying the damage index with cumulative AE energy is a complementary technique for detecting and assessing structure damage that well detects the occurrence of macrocracks.

• 한국방사선학회논문지
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• 제17권7호
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• pp.1049-1055
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• 2023

칼라도플러 초음파에서 요로결석의 종류에 따라 트윈클링 허상의 발생정도에 차이가 있는지 알아보고자 하였다. 색이 다른 두 종류의 요로결석에 대하여 물탱크에서 트윈클링 허상의 발생정도를 비교하고 결석의 표면과 성분을 분석하였다. 결석의 표면상태는 갈색의 결석에서 과립형 요철이 두드러져 보였다. 트윈클링 허상은 흰색의 결석에서 음향음영의 일부를 차지하는 1등급이 갈색의 결석에서 음향음영의 전체를 차지하는 2등급이 나타났다. 결석의 성분은 탄소와 산소를 제외한 칼슘과 인의 함유량이 가장 높게 나타났다. 결석성분 중 인의 함유량이 높을수록 결석표면이 매끄러우며 트윈클링 허상이 짧게 나타났다. 초음파검사로서 결석의 성분을 예측하기 위한 단편적인 역할을 기대할 수 있을 것이며 이는 결과적으로 치료계획에 도움이 된다.

• 한국잡초학회지
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• 제8권2호
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• pp.164-168
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• 1988

본(本) 연구(硏究)는 사과 과수원(果樹園)에서 잡초방제법(雜草防除法)을 확립(確立)하는데 필요(必要)한 자료(資料)를 얻고자 아산(牙山)과, 예산(禮山) 2개(個) 지역(地域)을 선정(選定)하여 약(約) 15일(日) 간격(間隔)으로 잡초(雜草)를 채취(採取)하여 잡초수(雜草數), 건물중(乾物重), 발생잡초(發生雜草)의 종생태적(種生態的) 및 사회적특성분석(社會的特性分析)과 우점도(優占度)를 구명(究明)한 결과(結果)는 다음과 같다. 1. 18과(科) 48종(種)이 발생(發生)했으며 명아주, 여뀌가 우점(優占)하였고 바랭이, 쇠비름, 망초가 차우점(次優占)하였다. 2. 잡초발생본수(雜草發生本數)는 4월(月), 건물중(乾物重)은 6월(月)과 10월(月)에 많았으며 여름 광엽잡초(廣葉雜草)의 발생(發生)이 많았고 월년광엽잡초(越年廣葉雜草)와 월년화본과잡초(越年禾本科雜草)는 봄에 발생(發生)이 많았다. 또한 연간(年間) 잡초(雜草)의 발생양상(發生樣相)을 보면 3월(月)에 발생(發生)하여 초여름까지 생육(生育)하는 초종(草種)은 월동잡초(越冬雜草)인 냉이, 둑새풀 이었으며 4월(月)에 발생(發生)하여 가을까지 생육(生育)하는 초종(草種)은 여뀌, 명아주였고 6월(月)에 발생(發生)하여 가을까지 생육(生育)하는 초종(草種)은 바랭이, 쇠비름 등(等)이었다. 3. 시기별(時期別) 종다양도(種多樣度), 최대종(最大種) 다양도(多樣度)와 안정도(安定度)가 높아 발생초종(發生草種)이 많은 숙전(熟田)이었으며 Simpson 지수(指數)도 높아 몇 초종(草種)이 우점(優占)하는 군락(群落)이었고 종간경쟁(種間競爭)이 종내경쟁(種內競爭)보다 높아 초종간(草種間) 경쟁(競爭)이 많았다.

• Clinical and Experimental Pediatrics
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• 제56권4호
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• pp.165-175
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• 2013

Purpose: There was a global increase in the prevalence of oseltamivir-resistant influenza viruses during the 2007-2008 influenza season. This study was conducted to investigate the occurrence and characteristics of oseltamivir-resistant influenza viruses during the 2007-2008 and 2008-2009 influenza seasons among patients who were treated with oseltamivir (group A) and those that did not receive oseltamivir (group B). Methods: A prospective study was conducted on 321 pediatric patients who were hospitalized because of influenza during the 2007-2008 and 2008-2009 influenza seasons. Drug resistance tests were conducted on influenza viruses isolated from 91 patients. Results: There was no significant difference between the clinical characteristics of groups A and B during both seasons. Influenza A/H1N1, isolated from both groups A and B during the 2007-2008 and 2008-2009 periods, was not resistant to zanamivir. However, phenotypic analysis of the virus revealed a high oseltamivir $IC_{50}$ range and that H275Y substitution of the neuraminidase (NA) gene and partial variation of the hemagglutinin (HA) gene did not affect its antigenicity to the HA vaccine even though group A had a shorter hospitalization duration and fewer lower respiratory tract complications than group B. In addition, there was no significant difference in the clinical manifestations between oseltamivir-susceptible and oseltamivir-resistant strains of influenza A/H1N1. Conclusion: Establishment of guidelines to efficiently treat influenza with oseltamivir, a commonly used drug for treating influenza in Korean pediatric patients, and a treatment strategy with a new therapeutic agent is required.

• 미생물학회지
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• 제39권2호
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• pp.89-94
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• 2003

호흡기 바이러스 분리 및 항원분석을 통하여 미래의 백신개발 및 항원 분석을 위한 역학적 자료를 제공하고자 2000~2001년 사이의 급성 호흡기 감염증 환자를 대상으로 호흡기 바이러스를 분리하여 그 특성을 조사하였다. 2000년도에 분리된 바이러스는 충 43주로서, 이 중 39주의 인플루엔자바이러스가 분리되었으며, A형이 23주, B형이 16주 관찰되었으며, 또한 아데노바이러스가 4주 관찰되었다. 그리고 2001년도에는 총 56주의 바이러스가 분리되었는데, 이는 모두 인플루엔자 바이러스로 확인되었다. 분리된 인플루엔자 바이러스의 주요항원별 특징으로는 A/Sydney/05/97(H3N2)-like, A/Beijing/262/95(H1N1)-like, 및 B/Harbin07/94-like가 2000년에, A/Panama/253/99(H3N2)-like 및 A/Newcaledonia/2007/99(H1N1)-like가 2001년에 분리되었으며, 아데노바이러스는 1, 2, 5형의 혈청형이 발견되었다. 분리된 바이러스의 성별 발생분포는 2000년에 남성환자 14명(32.56%), 여성 환자 23명(67.44%), 2001년에 남성환자 23명(41.07%), 여성환자33명(58.93%)이 발생하여 2000년과 2001년 모두 여성환자의 발생율이 비교적 높게 나타났다. 연령별 발생분포는 2000년에는 0-1세 사이에서 48.84%로 대부분을 차지하였으나, 2001년에는 l1∼20세 사이에서 33.93%로 비교적 높은 발생율을 나타내었으며, 그 외 연령별로는 비슷한 발생율을 나타내었다. 월별 발생분포는 2000년에는 1월에 한차례 높았다가 다시 4월에 다소 높은 발병율을 나타내었으며, 6월까지 낮은 비율이지만 다양한 바이러스가 출현하였다. 반면 2001년에는 2월과 3월에 집중적으로 발생하였으며 H3N2가 강력한 발병율은 나타내면서 주로 이른봄에 발생하였다.