• Bulletin of the Korean Chemical Society
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• 제24권9호
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• pp.1265-1268
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• 2003

The estimation of retention factors by correlation equations with physico-chmical properties maybe helpful in chromatographic work. The physico-chemical properties were water solubility (S), hydrophobicity (P), total energy ($E_t$), connectivity index 1 ($^1{\chi}$), hydrophilic-lipophlic balance (x) and hydrophilic surface area (h) of isoflavones. The retention factors were experimentally measured by RP-HPLC. Especially, the empirical regulations of water solubility and hydrophobicity were expressed in a linear form. The equation between retention factors and various physico-chemical properties of isoflavones was suggested as $k = a_0 + a_1\;log S + a_2log\;P^Q + a_3(E_t) + a_4(^1{\chi}) + a_5(x) + a_6(h)$, and the correlation coefficients estimated were relatively higher than 0.95. The empirical equations might be successfully used for a prediction of the various chromatographic characteristics of substances, with a similar chemical structure.

• 한국연초학회지
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• 제29권1호
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• pp.1-7
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• 2007

This study was conducted in order to predict the chemical and physical properties by climatic factors during the growing season of flue-cured tobacco as soon as possible. The data of eight chemical and five physical properties were collected from "Analysis of physical and chemical properties on farm leaf tobacco" conducted at KT&G Central Research Institute from 1987 through 2006. Data of climatic factors from April to July in 10 districts were collected from Korea Meteorological Adminstration. Except for yellowness(b), all probabilities of linear regression equations between the climatic factors(X) and the average contents of twelve grades(whole plant) for chemical and physical properties(Y) were significant($P{\leq}0.05$). The predicable probabilities within ${\pm}20%$ range of difference were 100% in ether extract content, in nicotine content, and in filling value, 90% in total nitrogen content, and 70% in total sugar content. These results suggest that the regression equations may be useful to predict the average content of twelve grades for eight chemical and four physical properties by climatic factors during the growing season of flue-cured tobacco at the beginning of August.

• 한국연초학회지
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• 제29권1호
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• pp.8-13
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• 2007

This study was conducted in order to predict the chemical and physical properties by climatic factors during the growing season of burley tobacco as soon as possible. The data of six chemical and five physical properties were collected from "Analysis of chemical and physical properties on farm leaf tobacco" conducted at KT&G Central Research Institute from 1987 to 2006. Data of climatic factors from April to July in 6 districts were collected from Korea Meteorological Adminstration. Except for total nitrogen, total nitrogen/nicotine and yellowness(b), all probabilities of linear regression equations between the climatic factors(X) and the average contents of twelve grades(whole plant) for chemical and physical properties(Y) were significant($P{\leq}0.05$). The predicable probabilities within ${\pm}20%$ range of difference were 100% in ether extract content, 95% in nicotine content, and 90% in filling value. These results suggest that the regression equations may be useful to predict the average content of twelve grades for four chemical and four physical properties by climatic factors during the growing season of burley tobacco at the beginning of August.

• The Journal of Asian Finance, Economics and Business
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• 제8권12호
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• pp.371-376
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• 2021

The article analyzes the impact of factors affecting the internal control system of chemical enterprises in Vietnam, providing more empirical evidence on factors affecting the system of internal control. Research data is collected in the form of face-to-face interviews and email interviews with managers and employees working in different positions, managers at all levels, chief accountants, and accountants of 52 chemical enterprises in Vietnam. The survey results collected 310 questionnaires. After eliminating the invalid questionnaires due to many blank cells, the authors chose to use 297 questionnaires. Quantitative research was carried out with SPSS 25 software. Research results show that Business Strategy, Organizational Structure, Organization's perception of the instability of the external environment, and Organizational culture are the factors that positively affect the internal control system of chemical enterprises. This can be explained that, for chemical enterprises, Business strategy, Organizational structure, Organization's perception of the instability of the external environment, and Good organizational culture will positively impact the internal control system of chemical enterprises. Based on the research results, the authors have proposed recommendations to enhance the effectiveness of the internal control system of chemical enterprises in Vietnam, thereby contributing to improving the performance of enterprises in the chemical Vietnamese.

• 한국안전학회지
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• 제34권3호
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• pp.57-64
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• 2019

Lack of incident reporting culture has been pointed out as a potential risk factor across industries. Consequently, comprehensive understanding of the factors affecting the willingness to report (WTR) is necessary. However, our knowledge on the related studies are not enough to date and even most parts of the existing studies have focused on patient safety, which makes it difficult to universally apply the factors to all industries. Therefore, this study aimed to identify WTR factors in chemical plants and evaluate the influence degree of the factors. To do this, 45 candidate factors were summarized throughout the previous studies and surveying plant safety staff. A questionnaire survey was conducted for 614 all employees from 9 chemical plants which belong to one company, and finally 32 WTR factors were identified throughout 520 responses. Of these, 19 factors were consistent with the previous studies and 13 factors were newly identified. The most influential factor was 'Views on the necessity of incident reporting', and 'Reporting practice by outcome severity', 'Fear of vilification, conflicts, blame, or sanctions' were followed. This result not only suggests various WTR factors suitable for chemical plants, but also shows need to derive specific factors that are appropriate to each industry. An empirical study could be expected to increase incident reporting by using these factors and verify its effectiveness on injury rate.

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.756-763
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• 2008

본 연구에서는 잉크젯용 전도성 금속 나노 잉크 개발을 목표로 통계적인 실험과 분석을 진행하여 재현성 있는 고품질의 은 나노 입자를 합성할 수 있는 기술을 개발하고자 하였다. 은 나노 입자는 상용 수계분산제 Daxad19를 이용한 용액 환원침전법을 통해 0.3 M의 고농도로 합성되었다. 합성에 주요한 영향을 주는 6개의 인자를 선정한 후 실험 계획법(Design-of-experiment)을 통해 실험을 수행하였다. 합성된 은 입자는 SEM, TEM, UV-Visible 등의 분석법을 이용하여 입자크기 및 분포와 분산도 등을 측정하였으며 통계 프로그램인 Minitab으로 이를 최적화하였다. 통계적인 실험계획 및 분석은 2차 부분요인분석법(2k-fractional factorial design)과 반응표면분석법인 박스-벤켄법(Box-Behnken design)으로 진행하였다. 이를 통한 합성 최적화로 평균입경 $30nm{\pm}10%$를 가진 구형의 은 나노 입자를 합성하였다. 또한 본 연구에서는 실험 결과 해석을 통해 환원침전법에서의 입자크기 및 형상 제어의 방식도 실험적으로 밝혀냈다.

• 한국물환경학회지
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• 제27권2호
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• pp.218-227
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• 2011

The objective approach for assessment of stream naturalness is an essential part of the stream restoration project. This study proposes the methodology for the assessment of stream naturalness considering physical, biological and chemical factors. Physical factors consists of riffle and pool, river bed material, bank protection, floodplain vegetation and levee materials; biological factors are benthic macroinvertebrate, KSI (Korean Saprobic Index), and IBI (Index of Biological Integrity) and chemical factors are pH, DO (dissolved oxygen), and TP (total phosphorus). This procedure is applied to the Mokgamcheon. As a result, the downstream of Mokgamcheon (zone I) needs the prompt improvement of stream naturalness, compared to the others (zone II and III). This evaluation technique will be an effective tool to quantify the stream naturalness and can be used to set the target of stream restoration project.

• 한국산업보건학회지
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• 제30권3호
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• pp.292-298
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• 2020

Objectives: The aim of this research is to establish Similar Exposure Groups (SEGs) for chemical and biological risk factors that occur in farm work involving 24 tasks among 15 crops. Methods: To categorize SEGs, work type, work environment, and similar tasks for each crop were considered. After confirming the chemical risk factors (pesticides, inorganic dust-total dust and PM₁₀, ammonia, and hydrogen sulfide) and biological factors (organic dust-total dust and PM₁₀, and endotoxins) that occur in the crops and tasks, similar crops and tasks were selected as SEGs. Results: Among chemical risk factors, pesticides was selected for the SEGs, which was categorized by open field, greenhouse, fruit, and specialty crops. For inorganic dust, open field (plowing harrowing, seedling, planting, harvest, and sorting and packing) and specialty crops (plowing harrowing, seedling, planting, and harvest) were selected as SEGs. For ammonia and hydrogen sulfide, livestock (preparation of farm, management of nursery bed, feeding, shipment and manure treatment) were selected as SEGs. For biological risk factors such as organic dust (total dust, PM₁₀) and endotoxins, open field (manure application), greenhouse (plowing harrowing, planting, manure application, and harvest), fruit (manure application), specialty crops (manure application, making furrows, mixing mushroom media, harvest, and sorting and packing), and livestock (preparation of farm, maintaining poultry litter, feeding, shipment and manure treatment) were selected as SEGs. Conclusions: To establish similar exposure groups in agriculture, it is important that the characteristics of each hazard factor are categorized by identifying risk factors occurring by tasks.

• Bulletin of the Korean Chemical Society
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• 제24권12호
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• pp.1757-1762
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• 2003

The interrelation between retention factors of several L-amino acids and their physico-chemical and structural properties can be determined in chromatographic research. In this paper we describe a predictor for retention factors with various properties of the L-amino acids. Eighteen L-amino acids are included in this study, and retention factors are measured experimentally by RP-HPLC. Binding energy ($E_b$), hydrophobicity (log P), molecular refractivity (MR), polarizability (${\alpha}$), total energy ($E_t$), water solubility (log S), connectivity index (${\chi}$) of different orders and Wiener index (w) are theoretically calculated. Relationships between these properties and retention factors are established, and their predictive and interpretive ability are evaluated. The equation of the relationship between retention factors and various descriptors of L-amino acids is suggested as linear and multiple linear form, and the correlation coefficients estimated are relatively higher than 0.90.

• Safety and Health at Work
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• 제14권1호
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• pp.17-30
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• 2023

The human reproductive system can be affected by occupational exposure to many physical and chemical risk factors. This study was carried out to review the studies conducted on the issue of the pathophysiological effects of occupational physical and chemical risk factors on the reproductive system of females and males. In this systematic review, the databases such as "Google Scholar," "Pub-Med," "Scopus," and "Web of Science" were used. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA 2020), the studies included in our study were published between 2000 and 2021. In order to extract the required data, all sections of the articles were reviewed. Out of 57 articles we reviewed, 34 articles were related to field studies and 23 articles to clinical studies. Among them, 43 studies dealt with the pathophysiological effects of chemical agents, six studies dealt with the pathophysiological effects of physical factors, and 8 studies dealt with the pathophysiological effects of physicochemical factors on the human reproductive system. Physical (noise, heat, and radiofrequency radiation) and chemical (such as carbamate and organophosphate pesticides, benzene, toluene, xylene, formaldehyde, NO2, CS2, manganese, lead, nickel, and n-hexane) risk factors had pathophysiological effects on the human reproductive system. The presence of these risk factors in the workplace caused damage to the human reproductive system. The rate of these negative pathophysiological effects can be reduced by performing appropriate managerial, technical, and engineering measures in work environments.