• Journal of Korean Society of Water and Wastewater
• /
• v.28 no.5
• /
• pp.601-608
• /
• 2014

A coagulation-flocculation (CF) process using aluminum sulfate as a coagulant was employed to treat highly suspended solids in tunnel wastewater. Response surface methodology (RSM) based on a Box-Behnken design was applied to evaluate the effects of three factors (coagulant dosage, pH and temperature) on total suspended solids (TSS) removal efficiency as well as to identify optimal values of those factors to maximize removal of TSS. Optimal conditions of coagulant dosage and pH for maximum TSS removal changed depending on the temperature ($4{\sim}24^{\circ}C$). As temperature increased, the amount of coagulant dosage and pH level decreased for maximum TSS removal efficiency during the CF process. Proper adjustment of optimal pH and coagulant dosage to accommodate temperature fluctuations can improve TSS removal performance of the CF process.

• Advances in nano research
• /
• v.12 no.4
• /
• pp.375-386
• /
• 2022

Synthesis of acrylate-based dispersion resins involves many parameters including temperature, ingredients concentrations, and rate of adding ingredients. Proper controlling of these parameters results in a uniform nano-size chain of polymer on one side and elimination of hazardous residual monomer on the other side. In this study, we aim to screen the process parameters via Internet of Things (IoT) to ensure that, first, the nano-size polymeric chains are in an acceptable range to acquire high adhesion property and second, the remaining hazardous substance concentration is under the minimum value for safety of public and personnel health. In this regard, a set of experiments is conducted to observe the influences of the process parameters on the size and dispersity of polymer chain and residual monomer concentration. The obtained dataset is further used to train an Adaptive Neural network Fuzzy Inference System (ANFIS) to achieve a model that predicts these two output parameters based on the input parameters. Finally, the ANFIS will return values to the automation system for further decisions on parameter adjustment or halting the process to preserve the health of the personnel and final product consumers as well.

• The Korean Journal of Applied Statistics
• /
• v.21 no.2
• /
• pp.201-210
• /
• 2008

The government employment statistics show the close comovement of the whole domestic unemployment rate with the youth unemployment rate for the past 10 years, implying the dominant influence of the unemployment of the youth age. This study investigates the structure of the short-run variation and the process of the long-run adjustment in the unemployment rates of the youth and middle ages by formulating the dynamic equation system. The estimation result consistently reflects the vulnerability of the youth class in the aggravation of the employment condition. The effect of exogenous changes is found to be persistent in the unemployment rates of both ages, which appear to have similar structures of the long-run time path. However, the youth unemployment rate turns out to have a relatively long adjustment process to the long-run equilibrium.

• Journal of Digital Convergence
• /
• v.14 no.11
• /
• pp.577-587
• /
• 2016

This study aims to understand the experiences of remarried elderly from the social, cultural point of view. The study subjects were randomly selected 3 remarried couples with age higher than 65 who could express their experience enough. This study adapted qualitative study with grounded theory method by Strauss and Corbin(1998), which deducted 126 significant sentences from the testimony of participants and classified those into 48 topics and categorized into 16. As for the study result, the main phenomenon was the "ambivalence of marriage" and the mediation conditions for controlling were "trust and acknowledgement of spouse and family", and "proper compensation", and the reaction/mutual reaction strategy to correspond to this situation was "to put effort to understand spouse". Such results will contribute to understanding the essence of marriage adjustment of remarried elderly, and are expected to be the fundamental material to tend to realistic problems that the widowed elderly face and to lead successfully remarriage.

• Journal of The Korean Association For Science Education
• /
• v.39 no.3
• /
• pp.321-335
• /
• 2019

This study aims to explore the influencing factors and the process of enhancing science self-efficacy (SSE) and to lay the foundation in understanding science self-efficacy of students. The ten categories related to the science self-efficacy were derived through the coding of the interview data based on the grounded theory and paradigm analysis to develop a process model of science self-efficacy improvement. Through the process analysis, four cyclical phases were found in the process of enhancing SSE: 'Entering into learning science' phase, 'enhancing SSE' phase, 'adjustment' phase, and 'result' phase. More specifically, the phase of 'entering into learning science' is where students choose science track and stimulated to construct SSE. The phase of 'enhancing SSE' is where students taking a science track actively learn science and perform science activities. In the phase of 'adjustment', students come to have successful performance about learning science and performing science activities by using diverse strategies. Finally, 'result' phase indicates different appearances of students depending on SSE levels. The phases were non-linear and periodically repeat depending on situation. The core category in the selective coding was indicated to be 'enhancing science self-efficacy.' Students' SSE form by learning science and performing science activities. These finding may help better understand the behavior of students who are taking a science track by facilitating effective science learning through the increase of their SSE levels.

• Korean Chemical Engineering Research
• /
• v.43 no.3
• /
• pp.352-359
• /
• 2005

This work has studied the changes of pH in both of anodic and cathodic chambers of a divided cell due to the electrolytic split of water during the ammonia decomposition to nitrogen, and has studied the continuous decomposition characteristics of ammonia in a multi-cell stacked electrolyzer. The electrolytic decomposition of ammonia was much affected by the change of pH of ammonia solution which was caused by the water split reactions. The water split reaction occurred at pH of less than 8 in the anodic chamber with producing proton ions, and occurred at pH of more than 11 in the cathodic chamber with producing hydroxyl ions. The pH of the anodic chamber using an anion exchange membrane was sustained to be higher than that using a cation exchange membrane, which resulted in the higher decomposition of ammonia in the anodic chamber. By using the electrolytic characteristics of the divided cell, a continuous electrolyzer with a self-pH adjustment function was newly devised, where a portion of the ammonia solution from a pHadjustment tank was circulated through the cathodic chambers of the electrolyzer. It enhanced the pH of the ammonia solution fed from the pH-adjustment tank into the anodic chambers of the electrolyzer, which caused a higher decomposition yield of ammonia. And then, based on the electrolyzer, a salt-free ammonia decomposition process was suggested. In that process, ammonia solution could be continuously decomposed into the environmentally-harmless nitrogen gas up to 83％, when chloride ion was added into the ammonia solution.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1750-1756
• /
• 2011

After Kyoto Protocol was adopted for green gas reduction, each nations are stepping up efforts to reduce $CO_2$ of a typical green gas. Construction industry also is trying $CO_2$ reduction with the techniques of two types which are software and hardware techniques. The software technique are Passive Design considered green gas emission and the environment impact assessment by LCA. The hardware techniques are adjustment of equipment system and development of eco- friendly material. But, it is nonexistent that a study related to $CO_2$ emission considered detail process in construction industry. This study analyzed the relativeness of equipment combination and $CO_2$ emission by calculate $CO_2$ emission follow to equipment combination on earth-work which is the process emitted most $CO_2$ among railway bedding construction.

• Journal of Advanced Marine Engineering and Technology
• /
• v.25 no.5
• /
• pp.1086-1090
• /
• 2001

In this paper, a method deciding the permissible gains of the P and PT controllers for a retarded process under stable condition is proposed. For analysis, the controlled process is assumed to be first-order system with time delay. At first, the adjustable parameter sets causing stability limit are obtained based on the frequency domain condition which makes the roots of the characteristic equation locate on the imaginary axis. And the cut-in frequency ${\omega}_p$ to bring the parameter set to P control from PI control is derived is derived in terms of L and $T_m$ then ${\omega}_p$ is used to compute the maximum gain with stable condition. The results indicate that the permissible controller gains can be described by a unique if parameters L and $T_m$ are know.

• Journal of the Korean Home Economics Association
• /
• v.36 no.11
• /
• pp.19-41
• /
• 1998

본 연구는 개인-환경 상호작용 가정을 바탕으로 한국의 두 가지 결혼 유형에 따른 배우자 선택과 결혼 적응의 메커니즘을 이해하기 위하여 개인, 과정, 맥락의 역할을 포함안 연구 모델 (person-process-context model)을 적용시켰다. 배우사 선택, 이에 따른 부부간 유사성과 결혼적응에 있어 개인과 사회적 특성의 상대적 기여도와 그 매커니즘을 조사하기 위해 154쌍의 한국 부부를 대상으로 설문조사 하였다. 연구결과에 의하면, 중매결혼과 연애결혼의 결혼유형에 관계없이 모두 동질혼의 경향을 보였다. 개인적 특성이 결혼 적응도와 높은 상관을 보인 반면, 부부간 유사성은 결혼 적응도와 유의한 상관이 업었다. 이는 결혼 적응에 있어서 환경적 요소(e. g. dyadic similarity)보다 개인적 요소가 중요하다는 것을 시사한다. 결혼유형에 따른 동질혼의 정도에는 유의한 차이가 없으며, 또한 동질혼의 정도에 따른 결혼적응도에는 유의한 차이가 발견되지 않았다. 연애결혼과 중매결혼의 중요한 차이는 결혼전 교제기간 이었다. 연애 결혼한 부부는 비교적 오랜 교제 기간을 통해 더 만족한 결혼생활을 영위하는 것으로 나타났다. 결혼전 교제기간의 효과를 통제한 후 두 결혼 유형의 결혼적응도에 대한 차이는 사라졌다. 연구결과들을 결혼과 성격에 관한 이론을 비탕으로 논의하였다.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.11a
• /
• pp.71-72
• /
• 2011

The construction industry in Korea has seen significant improvements in quality management techniques, driven by the dramatic development of new technology through enlargements, but compared with technical development, the level of building quality improvement is still lagging behind. Therefore, in this study, a work process and system improvement plan for payment regulations is proposed, with which contractors can secure quality voluntarily in the building construction project.