기술연재(2) 인터넷 비즈니스

주정환,Ju, Jeong-Hwan 한국데이터베이스진흥원 1998 디지털콘텐츠 Vol.11 No.-

어떻게 하면 이용자들의 시선을 단번에 사로잡을 수 있을까? 입 맛 까다로운 네티즌들을 자신의 홈페이지로 끌어들이기 위해서는 어떻게 해야 할까? 자신의 홈페이지를 글로벌 사이트로 변신시키기 위한 웹 프로모션 전략을 알아본다.

성공으로 가는 길(30)-자신을 끝없이 자극하고 조직화하며, 영상화 하라

주정환,Ju, Jeong-Hwan 대한기계설비건설협회 2007 기계설비 Vol.11 No.-

인간의 성공과 행복은 스스로 어떻게 하느냐에 달려있다. 끈기와 집념, 성실과 근면, 정직과 선의, 박애와 상조, 시간관리와 끊임없는 자기계발 등. 다시 말해 스스로 행복해지고 성공할 수 있다는 신념이 인간의 행복과 성공을 만든다. 어느 시대를 막론하고 사람들 중 일부는 국가나 제도의 힘을 빌려 행복과 성공을 보장 받으려 할 뿐 스스로 성취하려 하지 않는 경향이 있다. 지난 4월호부터 이런 낡은 정신에서 벗어나 보다 고양된 자세를 통해 삶을 깊이 있게 다듬어 나간 사람들의 이야기를 싣는다.

구리합금의 GTAW 및 레이저 용접부 미세조직 분석

주정환,정양일,이영우 대한용접·접합학회 2023 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2023 No.5

The nature of meiotic chromosome dynamics and recombination in budding yeast

홍수길,주정환,윤혜선,Keun Pil Kim 한국미생물학회 2019 The journal of microbiology Vol.57 No.4

During meiosis, crossing over allows for the exchange of genes between homologous chromosomes, enabling their segregation and leading to genetic variation in the resulting gametes. Spo11, a topoisomerase-like protein expressed in eukaryotes, and diverse accessory factors induce programmed doublestrand breaks (DSBs) to initiate meiotic recombination during the early phase of meiosis after DNA replication. DSBs are further repaired via meiosis-specific homologous recombination. Studies on budding yeast have provided insights into meiosis and genetic recombination and have improved our understanding of higher eukaryotic systems. Cohesin, a chromosome-associated multiprotein complex, mediates sister chromatid cohesion (SCC), and is conserved from yeast to humans. Diverse cohesin subunits in budding yeast have been identified in DNA metabolic pathways, such as DNA replication, chromosome segregation, recombination, DNA repair, and gene regulation. During cell cycle, SCC is established by multiple cohesin subunits, which physically bind sister chromatids together and modulate proteins that involve in the capturing and separation of sister chromatids. Cohesin components include at least four core subunits that establish and maintain SCC: two structural maintenance chromosome subunits (Smc1 and Smc3), an α-kleisin subunit (Mcd1/Scc1 during mitosis and Rec8 during meiosis), and Scc3/Irr1 (SA1 and SA2). In addition, the cohesin-associated factors Pds5 and Rad61 regulate structural modifications and cell cyclespecific dynamics of chromatin to ensure accurate chromosome segregation. In this review, we discuss SCC and the recombination pathway, as well as the relationship between the two processes in budding yeast, and we suggest a possible conserved mechanism for meiotic chromosome dynamics from yeast to humans.

Mec1 Modulates Interhomolog Crossover and Interplays with Tel1 at Post Double-Strand Break Stages

이민수,주정환,최형석,강현아,김근필 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.3

During meiosis I, programmed DNA double-strand breaks (DSBs) occur to promote chromosome pairing and recombination between homologs. In Saccharomyces cerevisiae, Mec1 and Tel1, the orthologs of human ATR and ATM, respectively, regulate events upstream of the cell cycle checkpoint to initiate DNA repair. Tel1ATM and Mec1ATR are required for phosphorylating various meiotic proteins during recombination. This study aimed to investigate the role of Tel1ATM and Mec1ATR in meiotic prophase via physical analysis of recombination. Tel1ATM cooperated with Mec1ATR to mediate DSB-to-single end invasion transition, but negatively regulated DSB formation. Furthermore, Mec1ATR was required for the formation of interhomolog joint molecules from early prophase, thus establishing a recombination partner choice. Moreover, Mec1ATR specifically promoted crossover-fated DSB repair. Together, these results suggest that Tel1ATM and Mec1ATR function redundantly or independently in all post-DSB stages.

What Determines the Voluntary Disclosure of CEO Succession Planning?

안민관,주정환 한국회계학회 2020 회계학연구 Vol.45 No.5

An established succession planning program for the identification and grooming of its next leader helps maintain the continuity of firm strategy and leadership style, which influences long-term firm performance and viability. Disclosure of succession planning information may alleviate investors’ doubts about whether the firm has a succession planning plan, while it may increase competition for CEO candidates, leading to increases in the cost of securing qualified candidates. This study explores what determines firms’ decisions to provide this disclosure using firms that initiate CEO succession planning disclosure in a given year and their control firms. We find that firms are more likely to initiate the disclosure of CEO succession planning when 1) segment concentration (negatively related to organizational complexity) becomes lower, 2) the board of directors becomes more independent, 3) the CEO has reached the retirement age of 64, 4) the CEO becomes more important relative to other executive officers in the industry labor market, 5) the number of analysts following (reflecting external monitoring) increases, and 6) CEO tenure (reflecting CEO entrenchment) declines. Overall, our findings suggest that the disclosure of CEO succession planning is motivated by investor demand for a smooth transition among top management and enhanced transparency in CEO succession planning.

Halothane 유도 산증이 국소성 뇌허혈증에 미치는 영향에 대한 실험적 연구

한기수,이기찬,주정환,이훈갑 대한신경외과학회 1993 Journal of Korean neurosurgical society Vol.22 No.8

The current study was performed to investigate the influence of acidosis on focal cerebral ischemia in view of morphometric assay and neuropathological examination. The acidosis was induced by increment of halothane concentration and by decreasing respiratory rate. The mean pH were 7.423±0.012 in control group and 7.184±0.038 in acidosis group. Twenty-four hours after MCA occlusion(MCAO), neutral red staining and perfusion fixation was performed. The ischemic area was measured and morphometric analysis was undertaken. In acidosis group, the infarct area was 25.23±4.78% of the total cerebral area ; in control group, the infarct area was 27.69±4.05%. The histopathological findings were examined under light microscopy, in which the field scanning was carried out from the midline by 0.5mm interval at cortical and basal ganglia leves. These results indicated that although there was no satistically significant difference in infarct area between acidosis and control group, increased acidosis aggravated the extent of histopathologic ischemic neuronal damage.

우라늄 분말 입자크기에 따른 Zr-U 금속연료의 성형 및 소결 미세조직의 영향

윤창근,전현준,주정환,이호진,이종탁,김형래 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.3

In case of the uranium (U) and zirconium (Zr) powders which have been utilized for the production of a metallic fuel in the various nuclear applications, the homogenous distribution of U powders in the Zr-U pellet has influenced significantly on the nuclear fuel performance. The inhomogeneity in a powder process was changed by various intricate factors, e.g. powder size, shape, distribution and so on. Particularly, the U inhomogeneity in the Zr-U pellets occurs by segregation derived from the great gaps of densities between Zr and U during compaction of the mixed powders. In this study, the relationship between powder size and homogeneity was investigated by using the different-sized U powders. The microstructure in Zr-U pellets reveals more homogeneity when the weight ration of Zr and U powders are close to 1. In addition, homogeneous pellets which were produced by fine U powders have higher density because the homogeneity affects the alloying reaction during sintering and the densification behavior of pore induced by powder size.

멸균된 치과기구의 유효기간에 관한 융합연구

나재경,박해련,성혜린,송인하,주정환,강경희 한국융합학회 2018 한국융합학회논문지 Vol.9 No.12

This study aimed to investigate the contamination rate of microorganisms by times after sterilization in mirrors, dental explorers, and pincettes which are the basic tools used in the dental clinic. 60 samples by each tool were used upon packaging them by 10 units. Contamination rate of microorganisms were tested using dry film media(3M Petrifilm Plates) which is a quick check upon collecting 10 samples right after sterilization, at Week 2, 3, 4, 5, and 6. At Week 0 when was right after sterilization, no microorganism was detected in any tools while they were detected in 2 mirrors, 2 dental explorers, and 2 pincettes at Week 6. 2 to 4 colonies on average were detected in mirrors at Week 2 and 4, 1 to 2 colonies in explorers from Week 5, and no colony was found in pincettes until Week 5 but 1 to 2 colonies at Week 6. Based on these results, the needs of effective periods are suggested for the sterilized tools together with their safe usages. 본 연구는 치과에서 사용하는 기본기구인 Mirror, Explore, Pincette에서 멸균 후 시간이 경과함에 따른 미생물 오염도를 알아보고자 하였다. 치과에서 주로 사용하고 있는 Mirror, Explorer, Pincette을 10개씩 포장하여 각 기구별 60개의 샘플을 사용하였다. 미생물 오염도는 멸균직후, 2주차, 3주차, 4주차, 5주차, 6주차에 10개의 샘플을 수거하여 건조필름배지(3M Petrifilm Plates)를 이용하여 검사하였다. 멸균 직후인 0주차에는 모든 기구에서 균이 검출 되지 않았으나, 6주차에서는 Mirror, Explorer, Pincette에서 각각 2개의 기구에서 균이 검출 되었다. Mirror에서는 실험 2주차와 4주차에서 평균 2-4개의 colony가 관찰 되었고, Explorer는 5주부터 평균 1-2개의 colony가 발견되기 시작하였으며, Pincette에서는 5주차까지 colony가 발견되지 않았으나, 6주차에서는 평균 1-2개의 colony가 발견 되었다. 이 결과를 바탕으로 보다 안전한 기구사용과 더불어 멸균기구의 유효기간의 필요성을 제시하고자 한다.