HPLC를 사용한 쌀 중 잔류농약 동시분석법

최재천,이영자,김소희,최수영,최희주,정성욱,박흥재,김우성 한국환경과학회 2005 한국환경과학회지 Vol.14 No.4

A simple and sensitive analytical method based on RP-HPLC with UV detector(225 nm) and mobile phases using 0.1% phosphoric acid and acetonitrile was developed for simultaneous determination of quinclorac, bentazone, 2,4-D, bensulfuron-methyl, dymuron, capropamide, pencycuron, ethofenprox. This method was resulted in recovery of 78~ 96% with RSD 3.3~7.5%. LODs 0.12~0.84 and LOQs 0.34~1.20 ㎎/L. Calibration curves were linear with r of 0.9995~ 0.9999.

Comparison of risk and protective factors associated with smartphone addiction and Internet addiction

Choi, Sam-Wook,Kim, Dai-Jin,Choi, Jung-Seok,Ahn, Heejune,Choi, Eun-Jeung,Song, Won-Young,Kim, Seohee,Youn, Hyunchul Akadémiai Kiadó 2015 JOURNAL OF BEHAVIOURAL ADDICTIONS Vol.4 No.4

<P><B>Background and Aims</B></P><P>Smartphone addiction is a recent concern that has resulted from the dramatic increase in worldwide smartphone use. This study assessed the risk and protective factors associated with smartphone addiction in college students and compared these factors to those linked to Internet addiction.</P><P><B>Methods</B></P><P>College students (<I>N</I> = 448) in South Korea completed the Smartphone Addiction Scale, the Young’s Internet Addiction Test, the Alcohol Use Disorders Identification Test, the Beck Depression Inventory I, the State–Trait Anxiety Inventory (Trait Version), the Character Strengths Test, and the Connor–Davidson Resilience Scale. The data were analyzed using multiple linear regression analyses.</P><P><B>Results</B></P><P>The risk factors for smartphone addiction were female gender, Internet use, alcohol use, and anxiety, while the protective factors were depression and temperance. In contrast, the risk factors for Internet addiction were male gender, smartphone use, anxiety, and wisdom/knowledge, while the protective factor was courage.</P><P><B>Discussion</B></P><P>These differences may result from unique features of smartphones, such as high availability and primary use as a tool for interpersonal relationships.</P><P><B>Conclusions</B></P><P>Our findings will aid clinicians in distinguishing between predictive factors for smartphone and Internet addiction and can consequently be utilized in the prevention and treatment of smartphone addiction.</P>

지역사회에서 형성된 사회적 지지와 근로자의 사회심리적 스트레스간의 관련성

임화영,김형수,최영환,장성훈,이건세,정최경희,오원기,최재욱,정춘화 대한산업의학회 2006 대한직업환경의학회지 Vol.18 No.4

Objective: This study was performed to examine the relationship between community-based social support and psychosocial distress in workers. Methods: The study subjects were 596 workers recruited from 11 companies in Chungju city. A structured questionnaire was used to assess sociodemographics, health-related behaviors, job characteristics, job stress, work-based social support, community-based social support and level of psychosocial distress. Results: Hierarchical multiple regression analysis showed that workers with no chronic disease, exercise and sufficient sleep had a higher score of psychosocial distress than those with chronic disease, no exercise, and not enough sleep. Coworker's work-based social support and community-based social support were negatively associated with psychosocial distress. The R square value of total independent variables on psychosocial distress was 0.409, and that of community-based social support on psychosocial distress was 0.052. Conclusion: This study showed that community-based social support served as a protective factor against psychosocial distress in some workers. We recommend the establishment of a worksite stress reduction program in occupational level as well as community-based social support.

도금액 조성 및 조업조건이 제품향상에 미치는 영향 연구

최인식,김운수,김우식,김용욱 경희대학교 산학협력기술연구원 1996 산학협력기술연구논문집 Vol.2 No.-

In this study the effect of operation conditions in silver plating process, such as solution concentration, agitation speed and plating time, on the plating thickness and quality was investigated. The plating thickness was significantly influenced by the concentration of silver ion in the plating solution and the plating thickness was increased by the silver ion concentration. However, the plating quality was dominantly affected by the operation conditions of agitation speed and plating time rather than the silver ion concentration. As the agitation speed of the plating solution increased, more uniform plating thickness was obtained and resulted in better quality of product. The thickness and quality of plating improved with increase of the plating time until it reached optimal time, but after then, the quality of plating was markedly dropped even though the thickness of plating increased with increase of plating time.

황산이온 포착용 보호컬럼을 가진 이온 크로마토그래피에 의한 선택적인 음이온의 동시검출

최용욱,김종훈,김미경,최윤정,이수영 전주대학교 자연과학종합연구소 1997 전주대학교 자연과학연구소 학술논문집 Vol.10 No.3

Simultaneous detection method for measuring anions in drinking water except sulfate ion was developed by suppressed ion chromatography. Eluent with existing composition between carbonate and bicarbonate made the separation of early eluting anions poor. Therefore, it is necessary to use weaker eluent to increase the resolution of them. However, this caused elution time of sulfate ion to take long, consquantely, total pinning time was more than 60 minutes. In order to resolve this problem by use of column switching with guard column for trapping sulfate ion, the resolution of the rest 8 anions was enhanced, total running time was also shortened within 10 minutes. Usage of eluent with existing composition made possible determination of sulfate ion on guard column within 4 minutes. Calibration curves of 8 anions represented linearity of better than 0.999 and detection limits by this method of all the anions considered were between 0.04 and 0.002 mg/L

복합레진의 수리 시 표면처리가 결합강도에 미치는 영향

최정인,김영재,김정욱,이상훈,김종철,한세현,장기택 大韓小兒齒科學會 2008 大韓小兒齒科學會誌 Vol.35 No.4

본 연구의 목적은 표면처리가 기존의 레진과 새로운 레진 사이의 전단결합강도에 미치는 영향을 평가하는 것이다. 준비된 레진 시편을 6군으로 임의로 배분하여 각각의 표면처리를 한 후 수리용 레진을 축조하였다. 일주일간 보관 후 전단결합강도를 측정하였고 일원분산 분석법으로 통계처리하여 다음과 같은 결과를 얻었다. 1. 3군과 4군(air abrasion)은 1군(산부식)에 비해 전단결합강도가 유의하게 높게 나타났다(p<0.005). 5군과 6군(diamond bur)은 1군(산부식)에 비해 높은 전단결합강도를 나타냈으나 통계적으로 유의하지 않았다(p<0.005). 2. 2군(자가부식 접착제)은 1군(산부식)에 비해 전단결합강도가 낮게 나타났으나 유의한 차이는 없었다(p<0.005). 3. 3군(air abrasion)과 4군(air abrasion +산부식)에서 전단결합강도의 차이는 유의하지 않았다(p<0.005). 4. 5군(diamond bur)과 6군(diamond bur+산부식)에서 전단결합강도의 차이는 유의하지 않았다(p<0.005). 결론적으로,복합레진의 수리 시 air abrasion으로 표면처리를 했을 때의 결합강도가 가장 높았고,산부식 방법과 처리여부는 수리강도에 유의한 영향을 미치지 않았다. The purpose of this study was to evaluate the effect of surface treatment on the shear bond strength between new and old composite resin. The prepared resin specimens were separated 6 groups, and each group then received a different surface treatment. Then the repair material was added. Shear bond strengths for repair were measured after 7 days and the results were analyzed by using one way ANOVA. The results were as follows ; 1. Group 3, 4(air abrasion) showed significantly higher shear bond strength than Group l (phosphoric acid)(p<0.05). Group 5, 6(diamond bur) showed higher bond strength than Group l(phosphoric acid) but not significantly different(p<0.05). 2. Group 2(self-etching adhesive) showed lower shear bond strength than Group 1 (phosphoric acid) but not significantly different (p<0.05). 3. There was no statistically significant difference between Group 3 (air abrasion) and Group 4(air abrasion + etching). 4. There was no statistically significant difference between Group 5(diamond bur) and Group 6(diamond bur+etching). In conclusion, the surface treatment with air abrasion resulted in higher repair bond strength than other methods. Repair bond strength was not significantly affected by acid etching.

교육에서의 컴퓨터 활용에 따른 교사의 역할 전환

최욱,고영남 고려대학교 교육문제연구소 1998 敎育問題硏究 Vol.10 No.-

가새배치에 따른 고층건물의 변위에 관한 연구

최영화,임헌욱 대구대학교 산업기술연구소 2014 産業技術硏究 Vol.25 No.1

Mordern structures tend to be high-rise buildings because of the population growth, restraint of lands and the high value of lands. In aspect to the control of lateral displacement, the importance of wind load and seismic load is also increasing to get the resistance against lateral load. The purpose of this study is to analyze the base building and 12-case models according to the bracing arrangement, the relative stiffness ratio of column and girder, the number of floor and the bracing section area by using MIDAS/GENw computer program. The results are as followings ; 1. Case 2 is effective in the vertical bracing arrangement. 2. Case 6 is effectual in the group bracing arrangement. 3. Case 8 and 10 are efficient in the diagonal and the horizontal bracing arrangements, respectively. 4. Case 8 among the diagonal bracing arrangements shows the smallest displacement value in all 12 cases, compared with the base building by decreasing as much as 48%.

태권도 전공 대학생의 정신건강에 관한 연구

최영렬,윤정욱 경희대학교 체육과학연구소 2004 體育學論文集 Vol.32 No.-

This study mainly focuses on finding differences in mental health state between groups which are divided according to the degree of specialty, sex, grade and career. The goal of study is to analyze the level of mental health state in each group and to investigate symptoms in which the differences occur and to find the reason why some groups show different mental health state. As a results, there are some distinctive differences between groups in the degree of specialty and sex. And no differences between groups in grade and career. Sexual identity cause differences between groups in sex, and continuous feeling about victory or defeat of the match bring harmful mental health in effect in high degree of specialty group. Even if physical exercise help to improve and maintain sound mental health state, psychological tension and stress give a negative effect on mental health state.

黃柏에서 抽出한 多糖類의 抗癌作用에 대한 硏究

최영철,홍희탁,홍영욱,이태균,박원환,김철호 동국대학교 경주대학 1997 東國論集 Vol.16 No.1

In order to investigate antitumor activities of the extracted polysaccharides from Phellodendron chinense SCHNEID, the following studies were carried out. Phellodendron chinense SCHNEID was extracted with hot water and alkali, and the extracted polysaccharides showed antitumor activities against mice Sarcoma-180 solid tumors in parameters of tumor weight, inhibition ratio, thymidilate synthetase(TS) and thymidine kinase(TK) activities. The results were as follows : 1. Delipidated extracts from Phellodendron chinense SCHNEID, were systematically fractionated, the heteropolysaccharide contains D-N-acetylglucosamine, D-galactose, D-mannose, D-glucose. The molecular weight distribution of the sample was found to be nearly homogeneous (about from 200 to 1000 kDa) in gel permeation analysis. 2. Among the polysaccharide fractions, the water extracted fractions, particularly Fr.-2, showed a potent growth-inhibitory activity against implanted in mice Sarcoma 180 solid tumor (inhibition, 95.3%, at 2 ㎎/100g), but the cold alkali extract (Fr.-4) showed a very low activity (inhibition; 4.7%). Fr.-7 and Fr.-8 showed the highest tumor inhibitory activity (inhibition; 96.4 and 98.2%, respectively). 3. TS activity in the Fr.-2 given oral administration of propolis was markedly suppresed to 73.7% of that in the control (p<0.01 by Student's t-test). However, there was little difference in TK activity with a slight decrease in Fr.-2 only.