• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.155-160
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• 2004

Permeation experiments of a commercial nanofiltration membrane (nominated as ESNA 1) were carried out with aqueous solutions of various single salts, that is, five chlorides (NH$_4$Cl, NaCl, KCl, MgCl$_2$ and $CaCl_2$), three nitrates $(NaNo_3,\;Mg(No_3)_2\;and\;Ca(NO_3)_2)\;and\;three\;sulfates\;((NH_4)_2SO_4,\;Na_2SO_4\;and\;MgSO_4)$. The experimental results showed that (1) the permeate volume flux of the ESNA 1 membrane increased and decreased with the growth of the applied pressure and the feed concentration of salts, respectively. The real rejection of ESNA 1 membrane to most single salts increased with the growth of the permeate volume flux. (2) The reflection coefficients of ESNA 1 membrane to chlorides, nitrates and sulfates are 0.97, 0.96 and 0.99, respectively. The solute permeability of most salts except for magnesium and calcium salts increased with the growth of feed concentration. (3) The sequence of the rejections of ESNA 1 membrane to anions is $R({SO_4}^{2-})>R(CI)>R(NO_3)$ at the same feed concentration. While the sequence of the rejections to cations is cataloged into two cases: $R(Na^+)>R(K^+)>R(Mg^{2+})>R(Ca^{2+})$ at the concentration of 10 mol/$m^3$ and $R(Mg^{2+})>R(Ca^{2+})>R(Na^+)>R(K^+)$ at the concentration of 100 mol/$m^3$. The separation capability of a NF membrane is usually affected by the electrostatic effect and the steric-hindrance effect. In this case, the electrostatic effect is the major factor at low concentration and the steric-hindrance effect is the major factor at high concentration. Both the specific sorption and the hydration also reasonably influenced the separation performance of NF membrane to salts.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.462-470
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• 2011

ARS (Automatic Response Systems) based on VUI (Voice User Interface) and TTI (Touch Tone Interface) are one of the most widely used communication systems. Despite common usages, however, inconvenience of ARS is continually pointed out. This may stem from lack of human-centered studies aside from technological development. In this paper, we provide guidelines for designing ARS by analyzing hindrance factors of usability of ARS menu structure. We had selected two call-centers using ARS, and carried out an experimental study where subjects performed the task of "returning books." After that, they completed questionnaires and interviews. We identified four problems: the complex menu structure, lack of representativeness on the menu name, users' awareness of location, and a difficulty to move among menus. And we partially discussed the ways of avoiding the problems.

• Journal of the Korean Society of Food Culture
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• v.11 no.3
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• pp.393-402
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• 1996

The purpose of this study was to get data on the job attitude of cooks. This study was surveyed 216 cooks who work for deluxe hotels at Pusan. The results were summarized as follow: 1. The cooks think that their devotion is most important source for the best cooking. The next are taste, quality of raw materials, skill and hygiene in order. 2. 57.9% of the cooks think that a degree of expertise their field are average, but 73.6% cooks believe that the degree of expertise is higher than the other restaurant cooks. 3. They think that a good cook should be sincere and have proficiency of skill, good human relationship and study attitude, but they also believe an academic background and knowledge is not important to be a good cook. A deficiency of knowledge about cooking is what cooks believe to be the greatest hindrance for progress of cooking skills. The next hindrance are, a shortage of endeavor and authority of management. 4. The cooks believe that the ability of cooking is most important for a promotion, the others are, in order, human relationship, career background and age. 5. The cooks show little satisfaction with their job, but express their unsatisfaction with their pay. Also the cook's social status is mean. 6. The cooks recognize that a change in hotel policy is most important for the cooking department of the hotel. The next are, in order, enlargement of working space, arrangement of equipments and hiring of experts. 7. The cooks think that Japanese cooking have the best prospect in a food and beverage enterprise, while Chinese cooking have relatively lower prospect.

• Bulletin of the Korean Chemical Society
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• v.11 no.6
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• pp.521-527
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• 1990

The binding characteristics and analytical applications of anilinium ion complexes with 18-crown-6 were studied by polarography and NMR. First, the electrochemical reduction of the 10 species of mono and dimethylsubstituted anilinium ion complexes with 18-crown-6 as host in methanol are examined. The addition of 18-crown-6 to anilinium guest solution the polarographic waves remain well defined but shifted toward more negative potentials, indicating the complex formation. The values of formation constants, log Κ for 10 species of methylsubstituted anilinium ion complexes with 18-crown-6 varies from 2.7 to 4.8 in methanol at $25^{\circ}C$. The stability order of complexes for 18-crown-6 is anilinilum > 4-methyl > 3,4-dimethyl > 3-methyl > 3,5-dimethyl > 2,4-dimethyl > 2,5-dimethyl > 2,3-dimethyl > 2-methyl > 2,6-dimethylanilinium ion. The steric hindrance shows significant effect. Second, Proton NMR was used to elucidate their interaction characteristics. From the results of so called NMR titration techniques, the behaviors of binding sites on complexation, and the stoichiometry and stability order of complex were obtained. And the later results show the satisfactory agreement with the quantitative values obtained by polarography. Finally, the individual determinations of anilinium ion mixtures were also accomplished by addition of 18-crown-6. In some mixtures of methyl or dimethylanilinium ions the reduction peaks of differential pulse method appeared into one unresolved wave attributed to the small difference of half-wave potential, ${\Delta}E_{1/2}$. In the presence of 18-crown-6, the polarographic waves were resolved into individual maxima because of the shift toward more negative direction by the difference of selectivity of anilinium ions with 18-crown-6. It may be concluded that quantitative analysis of methylanilinium ion mixture make possible because the half-wave potential shift by the selectivity difference due to the steric hindrance between methyl group and 18-crown-6 on complexation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.06a
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• pp.265-268
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• 2011

이 연구는 초등교육에서 사이버가정학습의 참여를 저해하는 요인을 도출하고, 그 요인 중 가장 영향을 많이 미치는 요인을 찾음으로써 참여율을 제고하는데 목적이 있다. 연구목적을 달성하기 위해 선행연구 분석을 통해 8가지 잠정적 저해요인(학습동기 및 태도의 문제, 컴퓨터에 대한 부담감, 컴퓨터 사용의 어려움, 새로운 학습방법의 어려움, 학습설계의 문제, 상호작용의 어려움, 화면설계의 문제, 환경상의 문제)를 도출하였다. 이에 따라 33문항으로 구성된 설문지를 제작하여 사이버가정학습을 실시하고 있는 초등학교(3학년~6학년 학생 429명)을 대상으로 설문조사를 실시하였다. 로지스틱 회귀분석을 통해 분석한 결과, 초등교육에서 사이버가정학습 참여 저해에 영향을 주는 요인은 학습동기 및 태도의 문제, 컴퓨터 사용의 어려움, 컴퓨터에 대한 부담감, 새로운 학습방법의 어려움, 학습설계의 문제 이었다. 이중에서 참여 저해에 대한 영향력은 컴퓨터에 대한 부담감, 새로운 학습방법에 대한 어려움, 컴퓨터 사용의 어려움, 학습설계의 문제 순으로 4가지였다. 즉, 컴퓨터에 대한 부담감, 새로운 학습방법에 대한 어려움, 컴퓨터 사용의 어려움, 학습설계의 문제가 적을수록 지속할 가능성이 더 큰 것으로 나타났다. 연구결과를 토대로 초등교육에서 사이버가정학습 참여율을 제고하기 위해서 다음과 같은 결론을 내릴 수 있다. 첫째, 초등학생을 대상으로 한 사이버가정학습 운영 시 컴퓨터에 대한 부담감이나 새로운 학습방법에 대한 어려움, 컴퓨터 사용의 어려움이 있는지 고려해 초등학생에 맞는 적절한 학습설계를 구축하는 것이 중요하다. 둘째, 초등교육에서 사이버가정학습의 참여 저해요인에 가장 큰 영향을 미치는 컴퓨터에 대한 부담감을 줄이기 위해 학습자가 컴퓨터에 대한 두려움을 없애주고 컴퓨터가 학습에 유용하다고 느낄 수 있도록 초등학생을 위한 맞춤형 교수설계 및 콘텐츠 개발로 컴퓨터에 쉽게 접근하고 즐거움을 느낄 수 있도록 유도해야 한다.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.509-511
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• 2019

Hydrazine derivatives used in fine chemicals, pharmaceuticals and cosmetics can be synthesized by reduction reaction from diazonium derivatives. The reduction method using $SnCl_2$ facilitates the reaction conversion, but the use of $SnCl_2$ is limited when residual heavy metals are issued in the final product. For the conversion of protected (2-hydroxyphenyl)diazonium derivatives into its hydrazine derivatives in Ramalin preparation process, the reduction method was developed by using $NaHSO_3$. In this study, the effect of steric hindrance according to the protected 2-hydroxygroupinphenyldiazonium derivatives was found, and linear C1~C5 alkyl groups for the hydroxy protection were preferable during the diazonium reduction reaction. Considering the economical efficiency and industrial production for the preparation of Ramalin, a variety of protecting groups were investigated. As a result, 2-(allyloxyphenyl)hydrazine was obtained with 85% yield and 99.7% purity when the hydroxy protecting group was used as an allyl group that could be easily deprotected.

• Journal of the Korea Convergence Society
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• v.13 no.5
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• pp.69-75
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• 2022

This study investigated the English learners who are over 40 on their attitudes and perception for lifelong education by dividing them into age groups of middle aged and elderly learners. To this end, from May 20, 2020 to June 30, 2021, 80 participants attending lifelong education centers in North Gyeongsang province were surveyed on the demographic characteristics and interest, necessity, passion, advantage, hindrance, learning motivation, preferred subjects, and learning methods. As a result, it was found that elderly learners showed a more positive English learning attitude than middle-aged learners, and both groups considered the communication area important in their learning motivation and preferred subjects. In regard to hindrance toward English learning, different factors were shown according to the age groups along with lack of confidence in English. Differences were also shown in preferred learning methods. This study suggested the possibility of learning outcomes according to the positive learning attitude of elderly learners along with the need for detailed English program design according to learners' age.

• 재활복지
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• v.21 no.1
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• pp.279-299
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• 2017

This study is to investigate what the factors motivating the wheelchair basketball club members to participate in the wheelchair basketball club are and what the factors hindering the members from participating in the wheelchair basketball club are, based on which it has been conducted to explore the effective direction of the management of the wheelchair basketball club for the physically disabled persons in the future. For this study, a survey targeting 180 members currently participating in the wheelchair basketball clubs in Seoul, Gyeonggi, Chungcheong, Gyeongnam, Jeju areas has been conducted and the data gained from 144 respondents of them have been analyzed and its key results of this study are as follows. Firstly, the results of analyzing the physically disabled persons' motives of participation in the wheelchair basketball club show that the respondents have most frequently participated in the wheelchair basketball club by their motives of the pastime-oriented type, which was followed by the health-oriented one, then by the home-oriented one. The results of examining the difference in the motivations for participation based on the degree of participation in the wheelchair basketball club and on the social demographic characteristics of the club members show that there was a significant difference depending on the group by residence, the subjective health condition in the light of the pastime-oriented motives and there was significant difference depending on the age, the occupation, the group by residence, the frequency of participation. Secondly, according to the results of investigating and analyzing the factors hindering the members of the club from participating in the wheelchair basketball club for the physically disabled persons, the structural factors are found to have been the biggest hindrance factor of participation and there was a significant difference depending on the age, the highest level of education, the occupation, the frequency of participation in the club in verifying the difference in the hindrance factors of participation in the club in accordance with the social demographic characteristics of the club members and the frequency of participation in terms of internal factors. Based on the abovementioned research results, some future effective management strategies of the wheelchair basketball club for the physically disabled persons have been discussed.

• Journal of Environmental Health Sciences
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• v.20 no.2
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• pp.28-38
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• 1994

New problems have been recently posed on the abnormal foaming (Scum) in an aeration tank and the sludge flotation in a final sedimentation tank during the activated sludge process. However, the activities of the causing bacteria, Nocardia-amarae in an aeration tank have not been searched out at all. Therefore, in this article the activities of Nocardia-amarae in an aeration tank have been closely examined by means of the changes of (F/M) ratio, SRT and inflowing substrate using continuous type and fed-batch type. Summarized results of experiments are as follows. 1. Regrading continuous culture when synthetic wastewater was used substrate neither the increase in the number of Nocardia-amarae in the aeration tank nor the Occurrence of Scum was observed. 2. In the case of fed-batch culture, Nocardia-amarae in the aeration tank increased due to the partial change in substrate and the effect of SRT was significant. 3. Once the scum was formed and the quantity of added Nocardia-amarae and substrate were not changed, the effect of STR was not significant.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.70-71
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• 2015

Construction period is longer than the non-disclosure in civil construction of apartment house. And this process is intensive at the beginning and end of construction. Because this project management expertise is required. Nevertheless, subsidiary work(Working avoid a tendency of advanced technician, Frequent turnover and employment contracts, etc.) management attention of construction is at a lower level. Because of, there are the bad factors(trial and error, finish degradation, etc.). Therefore, this study analyzed Hindrance Factor of quality control on apartment complex construction work and presented importance of civil construction engineer's role. Also, forms of civil construction engineer, Performance experience and technical Strength of apartment complex construction was investigated for the construction. To this end, It analyzes the relationship between forms of civil construction engineer, Performance experience and technical Strength of apartment complex construction and Construction of evaluation as required by Construction Technology Management Act.