• Title/Summary/Keyword: system separation method

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Characterization of Gas Permeation Properties of Polyimide Copolymer Membranes for OBIGGS (OBIGGS용 공중합체 폴리이미드를 이용한 기체분리막의 투과 특성평가)

  • Lee, Jung Moo;Lee, Myung Gun;Kim, Deuk Ju;Nam, Sang Yong
    • Membrane Journal
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    • v.24 no.4
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    • pp.325-331
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    • 2014
  • We synthesized novel polyimides with high gas permeability and selectivity for application of on board inert gas generation system (OBIGGS). 2,2-bis(3,4-carboxylphenyl) hexafluoropropane dianhydride (6FDA) and two kinds of amines with high permeability and solubility were used to prepare the novel polymide. 2,3,5,6-Tetramethyl-1,4-phenylenediamine (TMPD) was used to improve gas permeability and various kinds of diamines were used to improve the gas selectivity respectively. The polyimide copolymers were synthesized by commercial chemical imidization method and their average molecular weights were over 100,000g/mol. The glass temperature ($T_g$) and the thermal degradation temperature were characterized using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The synthesized copolymers showed high $T_g$ over $300^{\circ}C$ and high thermal degradation temperature over $500^{\circ}C$. The gas permeation properties were measured by time-lag equipment. Although general polyimides showed very low gas permeability, synthesized polyimide copolymer showed high $O_2$ permeability of 36.21 barrer with high $O_2/N_2$ selectivity around 4.1. From this result, we confirm that these membranes have possibility to apply to OBIGGS.

Equilibrium, Kinetics and Thermodynamic Parameters Studies on Metanil Yellow Dye Adsorption by Granular Activated Carbon (입상활성탄에 의한 메타닐 옐로우 염료의 흡착에 대한 평형, 동력학 및 열역학 파라미터에 관한 연구)

  • Lee, Jong-Jib
    • Applied Chemistry for Engineering
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    • v.25 no.1
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    • pp.96-102
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    • 2014
  • Adsorption of metanil yellow onto granular activated carbon were studied in a batch system. Various operation parameters such as adsorbent dosage, pH, initial concentration, contact time and temperature were optimized. Experimental equilibrium adsorption data were analyzed by Langmuir and Freundlich adsorption isotherm. The equilibrium process was described well by Freundlich isotherm model. From determined separation factor (1/n), adsorption of metanil yellow by granular activated carbon could be employed as effective treatment method. By analysis of kinetic experimental data, the adsorption process were found to confirm to the pseudo second order model with good correlation and the adsorption rate constant ($k^2$) decreased with increasing initial concentration. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The activation energy was determined as 23.90 kJ/mol. It was found that the adsortpion of metanil yellow on the granular activated carbon was physical process. The negative Gibbs free energy change (${\Delta}G=-2.16{\sim}-6.55kJ/mol$) and the positive enthalpy change (${\Delta}H=+23.29kJ/mol$) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

The Changes of Solid, Nitrogen and Phosphorus Concentrations in Pig Slurry Stored at Various Depth of Slurry Storage Tank (돼지분뇨슬러리의 액비조내 저장깊이별 고형물 및 질소, 인의 함량분포에 관한 연구)

  • Jeong, Kwang-Hwa;Chung, Eui-Soo;Park, Chi-Ho;Kwag, Jung-Hoon;Choi, Dong-Yoon;Yoo, Yong-Hee
    • Journal of Animal Environmental Science
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    • v.12 no.3
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    • pp.161-168
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    • 2006
  • This paper describes the changes of characteristics of pig slurry according to storing depth. Most of the substances containing pollutants, such as were Management of manure and wastewater from animal confinement facilities is a critical factor for pollution control. With proper treatment processing method in both solid and liquid forms, it can be used as a fertilizer and soil conditioner. In Korea, liquid-manure handling system is very popular because its treatment and application is easy and labor saving. In the storage tank treatment, the period of fermentation process and solids-liquid separation averages six months and the supernatant liquid is being used as a fertilizer. In this study, the changes in chemical characteristics of pig slurry at varying depths of the storage tank were investigated. Results showed that the pH value of the fermented pig slurry was > 7, while the major pollutants such as BOD, SS, N and P were highest in the bottom of the tank. Therefore, the above findings proved that varying depths in the storage tank can influence the concentration of pollutants of the fermented pig slurry.

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Arthscopic Treatment of Osteochondritis Dissecans in Femoral Condyle (관절경을 이용한 대퇴골과 박리성 골연골염에 대한 치료)

  • Kim Sung-Jung;Kyung Hee-Soo;Ihn Joo-Chul;Lee Seong-Man
    • Journal of the Korean Arthroscopy Society
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    • v.4 no.2
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    • pp.138-143
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    • 2000
  • Purpose : We analyzed clinical and radiological results of the treatment of osteochondritis dissecans in the femoral condyle under arthroscopic guidance. Materials and Methods : The study group consists 19 cases in 17 patients. Average follow up period was 34 months and average age was 16 years. The cases were classified by 4 different groups, using the fellowing system: Group 1-stable lesion and no specific treatment after arthroscopic examination; Group 2-early separation and multiple drilling; Croup 3-unstable lesion and Herbert screw fixation; Croup 4-loose body removal and/or crater curettage. The results were analyzed by the criteria of Hughston which including clinical and radiologic outcomes. Results : There were 14 cases$(74\%)$ of good and excellent results in 19 knees in which, $75\%$(3/4) in Group 1, $75\%$(3/4) in Group 2, $86\%$(7/8) in Group 3 and $33\%$(1/3) in Group 4. The result of Herbert screw fixation group was better than that of other groups with statistically significant differences. Conclusion : In the treatment of osteochondritis dissecans of skekletally immature patients, arthroscopic finding was reliable guidance in decision of treatment method and active fixation was recommended in patients with large, unstable lesion.

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Discrimination of Shreds of Frozen and Dried Alaska Pollack, Dried Pollack, and Cod using Electronic Nose (황태채, 북어채 및 대구채 판별을 위한 전자코 분석)

  • Hong, Eun Jeung;Kim, Ki Hwa;Park, Sue Jee;Kim, Ji Eun;Kim, Dong-Sul;Lee, Hwa Jung;Kim, Eun Jeong;Lee, Jae Hwang;Kim, Seung-Hee;Lee, Kwang-Ho;Noh, Bong Soo
    • Food Engineering Progress
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    • v.15 no.2
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    • pp.162-168
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    • 2011
  • In this study, discrimination of shred of frozen and dried Alaska pollack, shred of dried pollack and shred of cod using electronic nose based on mass spectrometer was carried out. Intensities of each fragment from shred of frozen and dried Alaska pollack by e-nose were completely different from those of dried pollack and cod. Each sample was analyzed, and discriminant function analysis was used for the discrimination of similar products. DFA plot indicated a significant separation of each shred of frozen and dried Alaska pollack, shred of dried pollack and shred of cod ($r^2$= 0.7787, F = 185.2). E-nose based on MS system could be used as an efficient method for discriminant of EMA foods.

Identification of Vegetable Oil-added Sesame Oil by a Mass Spectrometer-based Electronic Nose (Mass Spectrometer를 바탕으로 한 전자코를 이용한 식물성 유지가 혼합된 참기름의 판별 분석)

  • Son, Hee-Jin;Hong, Eun-Jeung;Ko, Sanghoon;Choi, Jin Young;Noh, Bong-Soo
    • Food Engineering Progress
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    • v.13 no.4
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    • pp.275-281
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    • 2009
  • Sesame oils are partially mixed with other vegetable oils due to high price in a Korean market. To find out authentic sesame oil, a mass spectrometer-based electronic nose (MS-based E-nose) was used. Sesame oil (Se) was blended with soybean oil (So) or corn oil (Co) at the ratio (Se:So, Se:Co) of 97:3, 94:6, 91:9, 88:12 and 85:15, respectively. Intensities of each fragment from sesame oil by MS-based E-nose were completely different from those of soybean oil or corn oil. The obtained results were used for discriminant function analysis (DFA). Volatile organic components (VOC) of soybean oil or corn oil were similar to those of fresh air and DFA plot indicated a significant separation of pure sesame oil and pure other oil. The group of the mixed oil was seperated with that of sesame oil in DFA plot and the added amount of soybean oil to sesame oil was correlated with discriminant function first score (DF1). MS based E-nose system could be used as an efficient method to investigate the purity of sesame oil.

A Study on Development of Mobile LNG Yard Tractor Refueling Standards (이동식 LNG 야드트랙터 충전 기준 개발 연구)

  • Ryou, Young-don;Yu, Chul-hee;Koo, Bon-deuk;Lee, Dong-won
    • Journal of the Korean Institute of Gas
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    • v.22 no.6
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    • pp.59-64
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    • 2018
  • As part of measures to reduce fine dust, the government is promoting a project to convert the fuel of Yard Tractors(YT, tractors operated at ports), from diesel to LNG (Liquefied Natural Gas). While a port having a small number of yard tractors, it is not proper to construct a stationary LNG fueling station and supply LNG to YT due to a problem of BOG (Boil off gas) generation. Therefore, it is necessary to make a regulation and a standard on mobile LNG YT refueling station installation and inspection as an alternative. In this study, we have investigated domestic and foreign mobile LNG refueling cases and refueling standards, including the USA and Europe. In addition, we have suggested the risk reduction method according to the cause after investigation of the cause of LNG accidents. And last, based on the proposed risk reduction measures, we have proposed an amendment to the Regulation of the Urban Gas Business Law in Korea. The proposed mobile LNG YT refueling amendment of the Regulation includes ; maintenance of the safety distance from the protection facility, installation of an interlock device to prevent refueling in places other than the authorized place, installation of the identification system through biometrics, separation of the tank lorry and tow vehicle before refueling, checking the wheel fixed status of tank lorry before refueling, construction of the impounding area, safety measures before, during and after refueling, etc. The safety standards proposed in this study could be used as a reference in establishing standards for mobile LNG vehicle refueling in the near future.

Progress in Nanofiltration-Based Capacitive Deionization (나노여과 기반 용량성 탈이온화의 진전)

  • Jeong Hwan Shim;Rajkumar Patel
    • Membrane Journal
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    • v.34 no.2
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    • pp.87-95
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    • 2024
  • Recent studies explore a wide array of desalination and water treatment methods, encompassing membrane processes such as reverse osmosis (RO), nanofiltration (NF), and electrodialysis (ED) to advanced capacitive deionization (CDI) and its membrane variant (MCDI). Comparative analyses reveal ED's cost-effectiveness in low-salinity scenarios, while hybrid systems (NF-MCDI, RO-NF-MCDI) show improved salt removal and energy efficiency. Novel ion separation methods (NF-CDI, NF-FCDI) offer enhanced efficacy and energy savings. These studies also highlight the efficiency of these methods in treating complex wastewater specific to various industries. Environmental impact assessments emphasize the need for sustainability in system selection. Additionally, the integration of microfabricated sensors into membranes allows real-time monitoring, advancing technology development. These studies underscore the variety and promise of emerging desalination and water treatment technologies. They provide valuable insights for enhancing efficiency, minimizing energy usage, tackling industry-specific issues, and innovating to surpass conventional method limitations. The future of sustainable water treatment appears bright, with continual advancements focused on improving efficiency, minimizing environmental impact, and ensuring adaptability across diverse applications.

Seeking Alternative Directions in Confirmation Education for Korean Protestant Church (한국교회 견신례 교육의 대안적 방향에 관한 연구)

  • Shin-Geun Jang
    • Journal of Christian Education in Korea
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    • v.75
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    • pp.7-31
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    • 2023
  • Purpose of study: The purpose of this essay is to seek an alternative direction for confirmation education within the context of Korean Protestant Church, addressing the following issues: 1) Confusion in the use of terminology on confirmation, 2) Superficial understanding of confirmation, and the absence or privatization of confirmation theology, 3) Formalized confirmation education based on the concept of rites of passage, and 4) The absence of denominationally structured confirmation education. Research content and method: To achieve this purpose, this essay attempts to foster an intradisciplinary and interactive dialogue on confirmation through a biblical, historical, and theological approach. Biblically, confirmation is to be understood as the unity of the baptism of water and the baptism of Holy Spirit, associated with the consecration of the baptized as royal priests through the baptism of Holy Spirit. Historically, as a part of the rite of Christian initiation, confirmation was a unified rite that has undergone a process of separation and reunification. Theologically, the rite of confirmation affirms the covenant of the Triune God given in baptism and is positioned between baptism and the Lord's Supper. Conclusions and Suggestions: In conclusion, this essay suggests an alternative form of Confirmation education that is oriented towards the following objectives: 1) Education that forms the identity given in the baptismal covenant, 2) Education that reflects characteristics of both baptism and the Lord's Supper, 3) Education that integrates the Bible, doctrine, and life of confirmand and, 4) Education based on an organic educational system.

Export Prediction Using Separated Learning Method and Recommendation of Potential Export Countries (분리학습 모델을 이용한 수출액 예측 및 수출 유망국가 추천)

  • Jang, Yeongjin;Won, Jongkwan;Lee, Chaerok
    • Journal of Intelligence and Information Systems
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    • v.28 no.1
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    • pp.69-88
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    • 2022
  • One of the characteristics of South Korea's economic structure is that it is highly dependent on exports. Thus, many businesses are closely related to the global economy and diplomatic situation. In addition, small and medium-sized enterprises(SMEs) specialized in exporting are struggling due to the spread of COVID-19. Therefore, this study aimed to develop a model to forecast exports for next year to support SMEs' export strategy and decision making. Also, this study proposed a strategy to recommend promising export countries of each item based on the forecasting model. We analyzed important variables used in previous studies such as country-specific, item-specific, and macro-economic variables and collected those variables to train our prediction model. Next, through the exploratory data analysis(EDA) it was found that exports, which is a target variable, have a highly skewed distribution. To deal with this issue and improve predictive performance, we suggest a separated learning method. In a separated learning method, the whole dataset is divided into homogeneous subgroups and a prediction algorithm is applied to each group. Thus, characteristics of each group can be more precisely trained using different input variables and algorithms. In this study, we divided the dataset into five subgroups based on the exports to decrease skewness of the target variable. After the separation, we found that each group has different characteristics in countries and goods. For example, In Group 1, most of the exporting countries are developing countries and the majority of exporting goods are low value products such as glass and prints. On the other hand, major exporting countries of South Korea such as China, USA, and Vietnam are included in Group 4 and Group 5 and most exporting goods in these groups are high value products. Then we used LightGBM(LGBM) and Exponential Moving Average(EMA) for prediction. Considering the characteristics of each group, models were built using LGBM for Group 1 to 4 and EMA for Group 5. To evaluate the performance of the model, we compare different model structures and algorithms. As a result, it was found that the separated learning model had best performance compared to other models. After the model was built, we also provided variable importance of each group using SHAP-value to add explainability of our model. Based on the prediction model, we proposed a second-stage recommendation strategy for potential export countries. In the first phase, BCG matrix was used to find Star and Question Mark markets that are expected to grow rapidly. In the second phase, we calculated scores for each country and recommendations were made according to ranking. Using this recommendation framework, potential export countries were selected and information about those countries for each item was presented. There are several implications of this study. First of all, most of the preceding studies have conducted research on the specific situation or country. However, this study use various variables and develops a machine learning model for a wide range of countries and items. Second, as to our knowledge, it is the first attempt to adopt a separated learning method for exports prediction. By separating the dataset into 5 homogeneous subgroups, we could enhance the predictive performance of the model. Also, more detailed explanation of models by group is provided using SHAP values. Lastly, this study has several practical implications. There are some platforms which serve trade information including KOTRA, but most of them are based on past data. Therefore, it is not easy for companies to predict future trends. By utilizing the model and recommendation strategy in this research, trade related services in each platform can be improved so that companies including SMEs can fully utilize the service when making strategies and decisions for exports.