• Journal of Biosystems Engineering
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• 제29권5호
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• pp.385-394
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• 2004

The objectives of this study were to investigate the effectiveness of rubber as an engine mount of walking-type cultivators and to determine its optimal spring constant and damping coefficient using a dynamic simulation of the engine mount system. Four different types of rubber mounts were tested to determine their spring constants and damping coefficients, and the best type was selected for the isolation of the engine vibrations transmitted to the handle. The total vibration levels transmitted to the handle when the rubber mounts weren't installed were 17.52 $m/s^2$. The total vibration levels transmitted to the handle when the rubber mounts were installed were 10.69 $m/s^2$ for Stripe 1, 11.33$m/s^2$ for Stripe 2, 10.92$m/s^2$ for Stripe 3 and 14.19$m/s^2$ for Hive, respectively, resulting in an average of $30\%$ reduction when compared with that without the engine mount. A dynamic model of the cultivator's engine-mount system and its simulation program were developed and verified. A method was proposed to determine the optimal spring constant and damping coefficient of the engine-mount system. It was found from the simulation that a spring constant of 4,100 kN/m and the largest damping coefficient were the most effective for the vibration isolation.

• 한국미생물·생명공학회지
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• 제31권4호
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• pp.342-347
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• 2003

세포들간의 응집 및 배양용기 표면에의 부착은 야생 점액 세균의 액체배양에 큰 장애물로 작용한다. 이러한 장애를 해결하기 위한 한 방안으로 야생 점액세균으로부터 자연적 분산 돌연변이 균주를 얻는 방법을 시도해 보았다. 실험 대상으로 사용한 균주 M. stipitatus KYC1001은 충남 계룡산의 토양에서 분리된 점액세균으로, 다른 점액세균들과 마찬가지로 액체배지 내에서 대부분의 세포들이 응집체를 형성하거나, 배양용기의 표면에 달라붙는다. 본 연구에서는 야생형 균주들이 세포응집체를 형성하거나 배양용기의 표면에 달라붙게 되는 반면 분산 돌연변이 세포들은 배지 내에 자유로이 떠돌아다니게 될 것이라는 특성을 이용하여, 배양액의 상등액만을 30일에 걸쳐 10회 계대 배양함으로서 분산되어 상등액에 존재할 자연적 분산 돌연변이 세포들을 농화 배양하였다. 그 결과, 액체배지에서 완전히 분산되어 성장하는 한 균주, KYC2001과 부분적으로 분산하여 성장하는 세 균주, KYC2002, 2003, 2004를 얻을 수 있었다.

• 한국철도학회논문집
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• 제14권3호
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• pp.234-239
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• 2011

선로하부를 굴착한 후의 가설교량 설치공법은 이동형 가로보를 갖는 공법으로 시공시 전차선 차단 및 레일절단이 불필요하고 열차운행 횟수가 많은 복선부에서도 적용 가능한 공법이다. 본 논문에서는 공사구간이 곡선부(R400)구간으로 가설교량 공법 시공 후의 변위특성을 검토하기 위해 변위계를 설치하고 열차 통과 시의 윤중 횡압을 계측하여 곡선부(R400)의 주행안전성 검토를 평가하였다. 측정결과 가설교량을 통과시 열차종별 윤중과 횡압의 최대값은 각각 국외 궤도성능평가 기준의 51%, 81% 수준으로 분석되어 윤중, 횡압 발생에 따른 궤도 안전성 측면에서는 큰 문제가 없을 것으로 판단된다. 또한 주행안전성의 평가기준이 되는 최대 탈선계수와 최대 윤중감소율은 열차종별에 관계없이 허용한계치의 49% 수준으로 그 기준치에는 못 미치는 것으로 나타나 열차 통과시의 주행안전성 확보에는 큰 문제가 없는 것을 알 수 있었다.

• 미생물학회지
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• 제48권4호
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• pp.229-239
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• 2012

Cronobacter spp. (formerly Enterobacter sakazakii), a Gram-negative bacillus, is a rare cause of meningitis and central nervous system infections. In England, the first case infected by this organism occurred in 1958. By July 2008, approximately 120 documented cases of Cronobacter spp. infection and at least 27 deaths have been identified from all around the world in the published literature and in reports submitted by public health sectors. In 2007, it was proposed by European organizations that the original taxonomy of E. sakazakii would be revised, to consist of five new species moved to a new genus, and identified as "Cronobacter". E. sakazakii has thus now been reclassified as 6 separate species in the new genus, Cronobacter, gen. nov., within the Enterobacteriaceae family. The new species are presently Cronobacter sakazakii, C. turicensis, C. malonaticus, C. muytjensii, and C. dublinensis; the sixth species is identified simply as genomospecies I, as currently including only two representative strains. The objectives of this review are to provide insight on (1) the classification and taxonomy of Cronobacter spp., (2) its clinical etiology and pathogenicity, (3) prequency of Cronobacter spp. in different categories of ready-to-eat food other than infant formula, (4) methods for detecting, isolating and typing Cronobacter spp., and (5) recent research trends for detecting Cronobacter spp.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.390-394
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• 2013

고정밀 광학계를 탑재한 관측 위성은 매우 높은 지향 안정성을 요구하지만 인공위성의 자세 제어를 위해 사용하는 반작용 휠, 극저온 냉각을 위한 cooler 등 다양한 진동원에 의해 미소 진동이 발생할 수 있다. 고정밀 탑재체를 외부 진동으로부터 보호하기 위한 가장 일반적인 방법은 진동이 전달되는 경로에 진동 절연장치를 도입하는 것이다. 본 논문에서는 미소진동 절연을 위한 1 축 능동 진동 절연장치의 개발 및 진동 절연 성능 시험을 기술하였다. 개발한 절연장치의 고유진동수를 조절하기 위해 원하는 강성을 갖는 membrane 구조를 설계하였으며 능동 제어를 위해 전자석을 사용하였다. 절연장치의 성능 시험 결과를 통해 능동 제어 시 고주파수 대역에서 절연성능의 저하 없이 공진의 크기를 줄일 수 있는 것과 개발된 진동 절연 장치가 미소 진동을 효과적으로 절연할 수 있는 것을 확인하였다.

• Molecules and Cells
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• 제39권10호
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• pp.768-775
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• 2016

The Arabidopsis female gametophyte contains seven cells with eight haploid nuclei buried within layers of sporophytic tissue. Following double fertilization, the egg and central cells of the gametophyte develop into the embryo and endosperm of the seed, respectively. The epigenetic status of the central cell has long presented an enigma due both to its inaccessibility, and the fascinating epigenome of the endosperm, thought to have been inherited from the central cell following activity of the DEMETER demethylase enzyme, prior to fertilization. Here, we present for the first time, a method to isolate pure populations of Arabidopsis central cell nuclei. Utilizing a protocol designed to isolate leaf mesophyll protoplasts, we systematically optimized each step in order to efficiently separate central cells from the female gametophyte. We use initial manual pistil dissection followed by the derivation of central cell protoplasts, during which process the central cell emerges from the micropylar pole of the embryo sac. Then, we use a modified version of the Isolation of Nuclei TAgged in specific Cell Types (INTACT) protocol to purify central cell nuclei, resulting in a purity of 75-90% and a yield sufficient to undertake downstream molecular analyses. We find that the process is highly dependent on the health of the original plant tissue used, and the efficiency of protoplasting solution infiltration into the gametophyte. By isolating pure central cell populations, we have enabled elucidation of the physiology of this rare cell type, which in the future will provide novel insights into Arabidopsis reproduction.

• 한국광물학회지
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• 제18권2호
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• pp.83-92
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• 2005

광물의 용해속도는 기후에 따라 지역적인 차이는 있으나, 일반적으로 화강암을 구성하는 광물중 장석류의 풍화속도가 다른 광물에 비해 비교적 빠르기 때문에 파손 정도는 장석의 안정성에 지배된다. 지구화학적 반응 모델링 결과, 강우에 의해서 화강암이 변질되는데 걸리는 시간은 다른 변수를 고려하지 않고 pH만을 고려한 pH=4.5인 산성수내에서의 변질속도와 비교할 때 일반적인 빗물(pH=5.7)보다 약 2.3배 더 빠른 것으로 계산되었다. 이러한 결과는 화강암질 석조문화재의 보존에 있어서 pH가 중요한 요소로 작용할 수 있음을 의미한다. 석조문화재의 풍화를 억제하기 위해서는 암석의 풍화특성이 우선적으로 규명되어야 하며, 가수분해, 산 반응 등의 화학적 풍화작용은 물과의 접촉에 의해 이루어지므로 물을 차단하기 위하여 발수코팅, 오일코팅 또는 건조환경을 조성하는 방안을 고려해야 할 것이다. 세척제와 생물방제를 이용할 시는 빗물이나 화강암과의 장기적 반응을 고려하여 중성화작용과 환원성 환경이 형성될 수 있는 재질의 선택이 매우 중요하다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 1999년도 춘계 학술대회지
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• pp.162-163
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• 1999

The goal of this research was (1) to describe the conditions and parameters required for the cell cycle synchronization and the accumulation of large number of metaphase cells in maize and other cereal root tips, (2) to isolate intact metaphase chromosomes from root tips suitable for characterization by flow cytometry, and (3) to construct chromosome-specific libraries from maize. Plant metaphase chromosomes have been successfully synchronized and isolated from many cereal root-tips. DNA synthesis inhibitor (hydroxyurea) was used to synchronize cell cycle, follwed by treatement with trifluralin to accumulate metaphase chromosomes. Maize flow karyotypes show substantial variation among inbred lines. thish variation should be sueful in isolating individual chromosome types. In addition, flow cytometry is a useful method to measure DNA content of individual chromosomes in a genotyps, and to detect chromosomal variations. Individual chromosome peaks have been sorted from the maize hybrid B73/Mol7. Libraries were generated form the DOP-PCR amplification product from each peak. To date, we have analyzed clones from a library constructed from the maize chromosome 1 peak. Hybridization of labeled genomic DNA to clone inserts indicated that $24\%,\;18\%,\;and\;58\%$ of the clones were highly repetitive, medium repetitive, and low copy, respectively. Fifty percent of putative low cpoy clones showed single bands on inbred screening, blots, and the remaining $50\%$ were low copy repeats. Single copy clones showing polymorphism will be mapped using recombinant inbred mapping populations. Repetitive clones are being characterized by Southern blot analysis, and will be screened by in situ hybridization for their potential utility as chromosome specific markers.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.121-126
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• 2010

The automotive weather strip has functions of isolating of water, dust, noise and vibration from outside. To achieve good sealing performance, weather strip should be designed to have the high contact force and wide contact area. However, these design causes excessive permanent deformation of weather strip. The causes of permanent deformation is generally explained to be the chemical material detrioration and physical variation and cyclic loading, etc. This paper introduces a numerical method to predict the permanent deformation using the time dependent viscoelastic model which is represented by Prony series in ABAQUS. Uniaxial tension and creep tests were conducted to obtain the material data. And the lab. test for the permanent deformation was accelerated during shorter time, 300 hours. The permanent deformation of weather strip was successfully predicted under the different loading conditions and different section shapes using the suggested numerical process.

• 대한간호학회지
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• 제28권1호
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• pp.104-116
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• 1998

The purpose of this study was to analyze the trends of family nursing research in Korea. The subjects were 62 articles, 132 master theses and 20 doctoral theses published during the period between 1970-1997.7. The results are as follows. 1. The types of research that were analyzed were factor isolating. 34.1%, factor relating, 54.2%, situation relating. 6.1% and situation producing, 3.7%. 2. Research designs were experimental studies, 6. 1%, non-experimental studies, 89.7% and qualitative research, 4.2%. Survey research was the method used in 82.7% of the papers. 3. On the research subjects, 94 papers dealt with the family member of a patient or a single person, 59 papers dealt with a patient and 7 papers dealt with whole family. 4. On the places of studies, 64.0% of the studies were done in hospital rooms, 12.9% in the communities and community facilities. 12.0% in schools, 10.7% in the home, and 0.4% an occupational setting. 5. The most frequently used family concept in the title of the articles was "family support"(59 papers) followed by family function and family burden. 6. The most frequently used family assessment tool was Family Environment Scale(FES) developed by Moos & Insel. 7, According to family nursing domain described by Murphy' and Meister'study, the subdomain, relationship of the family and disease was found 83.2%. 8. Four papers built conceptual frameworks based on various theories of researchers. Eleven papers applied family theories and five papers applied nursing theories. Based on the above findings the following suggestions are made. 1. The various domains of family nursing research should be used including in the relationship of family and health, health policy and family. transcultural family research, and theoretical approach to family. 2. Qualitative research should be used for family nursing research. 3. Family assessment tools should be developed for the Korean family.