• Clean Technology
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• v.15 no.1
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• pp.60-66
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• 2009

Adsorptive removal of tetrahydrothiophene (THT) and tert-butylmercaptan (TBM) that were widely used sulfur odorants in pipeline natural gas was studied using various ion-exchanged NaY zeolites at ambient temperature and atmospheric pressure. In order to improve the adsorption ability, ion exchange was performed on NaY zeolites with alkali metal cations of $Li^+,\;Na^+,\;K^+$ and transition metal cations of $Cu^{2+},\;Ni^{2+},\;Co^{2+},\;Ag^+$. Among the adsorbents tested, Cu-NaY and Ag-NaY showed good adsorption capacities for THT and TBM. These good behaviors of removal of sulfur compound for Cu-NaY and Ag-NaY zeolites probably was influenced by their acidity. The adsorption capacity for THT and TBM on the best adsorbent Cu-NaY-0.5, which was ion exchanged with 0.5 M copper nitrate solution, was 1.85 and 0.78 mmol-S/g at breakthrough, respectively. It was the best sulfur capacity so far in removing organic sulfur compounds from fuel gas by adsorption on zeolites. While the desorption activation energy of TBM on the Cu-NaY-0.5 was higher than NaY zeolite, the difference of THT desorption activation energy between two zeolites was comparatively small.

• Clean Technology
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• v.29 no.2
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• pp.87-94
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• 2023

The recovery of valuable metals from waste lithium-based secondary batteries is very important in terms of efficiently utilizing earth's limited number of resources. Currently, the cathode material of a LiFePO₄ battery, a type of battery which is widely used in automobiles, contains approximately 5% lithium. After use, the lithium in these batteries can be used again as a raw material for new batteries through lithium recycling. In this study, low-concentration sulfuric acid, a commonly used type of inorganic acid, was used to selectively leach the lithium contained in a waste LiFePO₄ cathode material powder. In addition, in order to compare and analyze the leaching efficiency and separation efficiency of each component, the optimalleaching conditions were derived by applying a two-step leaching process with pulp density being used as a variable during leaching. When leaching with pulp density as a variable, it was confirmed that at a pulp density of 200 g/L, the separation efficiency was approximately 200 times higher than at other pulp densities because the iron and phosphorus components were hardly leached at this pulp density. Accordingly, the pulp density of 200 g/L was used tooptimize the leaching conditions for the selective leaching and recovery of lithium.

• The Journal of Bigdata
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• v.7 no.2
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• pp.153-172
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• 2022

Online shopping has transformed and rapidly grown the entire market at the forefront of wholesale and retail services as an effective solution to issues such as digital transformation and social distancing policy (COVID-19 pandemic). Small business owners, who form the majority at the center of the online shopping industry, are constantly collecting policy changes and market trend information to overcome these problems and use them for marketing and other sales activities in order to overcome these problems and continue to grow. Objective and refined information that is more closely related to the business is also needed. Therefore, in this paper, through the collection and analysis of big data information, which is the core technology of digital transformation, key variables are set in product classification, sales trends, consumer preferences, and review information of online shopping malls, and a method of using them for competitor comparison analysis and business sustainability evaluation has been prepared and we would like to propose it as a service. If small and medium-sized businesses can benchmark competitors or excellent businesses based on big data and identify market trends and consumer tendencies, they will clearly recognize their level and position in business and voluntarily strive to secure higher competitiveness. In addition, if the sustainable growth of the online shopping mall operator can be confirmed as an indicator, more efficient policy establishment and risk management can be expected because it has an improved measurement method.

• Journal of the International Relations & Interdisciplinary Education
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• v.4 no.1
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• pp.57-83
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• 2024

This study aimed to investigate the impact of scores on the Test of Proficiency in Korean (TOPIK) among foreign exchange students on academic adaptation. Recruited students, approved by the Institutional Review Board (IRB), totaled seven, and their interview contents were analyzed using a comprehensive analysis procedure based on pragmatic eclecticism (Lee, Kim, 2014), utilizing six stages. As a result, factors influencing academic adaptation of Korean language learners for academic purposes were categorized into three dimensions: academic, daily life, and psychological-emotional aspects. On the academic front, interviewees pointed out difficulties in adapting to specialized terminology and studying in their majors, as well as experiencing significant challenges with Chinese characters and Sino-Korean words. Next, from a daily life perspective, even participants holding advanced TOPIK scores faced difficulties in adapting to university life, emphasizing the necessity of practical expressions and extensive vocabulary for proper adjustment to Korean life. Lastly, within the psychological-emotional dimension, despite being advanced TOPIK holders, they were found to experience considerable stress in conversations or presentations with Koreans. Their lack of knowledge in social-cultural and everyday life culture also led to linguistic errors and contributed to psychological-emotional difficulties, despite proficiency in Korean. Based on these narratives, the conclusion was reached that in order to promote the academic adaptation of Korean language learners, it is essential to provide opportunities for Korean language learning. With this goal in mind, efforts should be directed towards enhancing learners' academic proficiency in their majors, improving Korean language fluency, and fostering interpersonal relationships within the academic community. Furthermore, the researchers suggested as a solution to implement various extracurricular activities tailored for foreign learners.

• Clean Technology
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• v.30 no.2
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• pp.71-93
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• 2024

Recently, the establishment of a hydrogen-based economy and the utilization of low-carbon energy sources, particularly for shipping and power generation, have been in high demand in order to achieve carbon neutrality by 2050. In particular, ammonia is gaining renewed attention because it is capable of serving as a key facilitator for high-efficiency green hydrogen storage and transportation and it is also capable of serving as a low-carbon energy source. Although ammonia can be synthesized through the Haber-Bosch process, the high energy consumption and carbon emissions associated with this process result in minimal carbon reduction. To address the critical drawbacks of the traditional Haber-Bosch process, various thermochemical synthesis methods have been developed recently, allowing for the synthesis of ammonia with lower carbon emissions and a higher energy efficiency. Research is also progressing in the development of high-performance catalyst materials that are capable of demonstrating sufficient ammonia synthesis performance under milder process conditions compared to conventional methods. Additionally, a variety of different processes such as chemical-looping ammonia synthesis, plasma synthesis, and mechanochemical synthesis are being applied diversely. This review aims to provide a detailed overview of the emerging ammonia synthesis technologies that have been developed to effectively store green hydrogen for future applications.

• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.1-6
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• 2018

Also, t-cincreaseisdecreasein order In hydroponics, the accumulation of inorganic ions in the root zone are closely related to the irrigation volume. Therefore, the effects of irrigation volume on the growth and yield of tomatoes are very signigicant. This study was conducted to investigate the effect of irrigation volume on inorganic ions of root zone in hydroponic culture using coir substrate. The irrigation volume was adjusted to 4 levels depending on the integrated solar radiation for each growth period. The drainage ratio was calculated by daily amount of irrigation and drainage. The higher irrigation volume is, drainage ratio and water absorption tended to increase. But, the water absorption in the treatment of high irrigation volume was decreased in February and March compared to the treatment of medium high irrigation volume. By calculating monthly average irrigation volume and the drainage ratio, 120 to 1$40J/cm^2$ in January, 100 to $120J/cm^2$ in February, 80 to $100J/cm^2$ in March, 70 to $90J/cm^2$ in April and 60 to $75J/cm^2$ in May was detected as appropriate irrigation volume ranges which drainage ratio was 20-30%. The higher irrigation volume, the lower the concentration of ions decrease, which could prevent the accumulation of nutrients in the root zone. However, due to the characteristics of the coir substrate that absorbs ions, concentration of ions was significantly high when the drainage ratio was 20-30%. However, concentrations of P and K were sometimes lower in the drainage than that of irrigation water regardless of the treatment. Mg and S were the most highly accumulated ions even in the treatment of high irrigation volume. In low radiation season, there was no difference in the ion concentration in the drainage depending on the irrigation volume. In high radiation season, the lower irrigation volume, resulted to the higher ion concentration in the drainage. After March, it was difficult to prevent the increase of ions concetration in the drainage by only adjusting irrigation volume. Thus, it is necessary to decrease the EC of irrigation solution to prevent the accumulation of nutrients in the root zone.

• Proceedings of the Technology Innovation Conference
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• 1998.06a
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• pp.116-127
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• 1998

The Necessity of Cyber University. Within the rapidly changing environment of global economics, the environment of higher education in the universities, also, has been, encountering various changes. Popularization on higher education related to 1lifetime education system, putting emphasis on the productivity of education services and the acquisition of competitiveness through the market of open education, the breakdown of the ivory tower and the Multiversitization of universities, importance of obtaining information in the universities, and cooperation between domestic and oversea universities, industry and educational system must be acquired. Therefore, in order to adequately cope wi th these kinds of rapid changes in the education environment, operating Cyber University by utilizing various information technologies and its fixations such as Internet, E-mail, CD-ROMs, Interact ive Video Networks (Video Conferencing, Video on Demand), TV, Cable etc., which has no time or location limitation, is needed. Using informal ion and telecommunication technologies, especially the Internet is expected to Or ing about many changes in the social, economics and educational area. Among the many changes scholars have predicted, the development and fixations of Distant Learning or Cyber University was the most dominant factor. In the case of U. S. A., Cyber University has already been established and in under operation by the Federate Governments of 13 states. Any other universities (around 500 universities has been opened until1 now), with the help of the government and private citizens have been able to partly operate the Cyber University and is planning on enlarging step-by-step in the future. It could be seen not only as U. S. A. trying to elevate its higher education through their leading information technologies, but also could be seen as their objective in putting efforts on subordinating the culture of the education worldwide. UTRA University in U. S. A., for example, is already exporting its class lectures to China, and Indonesia regions. Influenced by the Cyber University current in the U.S., the Universities in Korea is willing .to arrange various forms of Cyber Universities. In line with this, at JUNAM National University, internet based Cyber University, which has set about its work on July of 1997, is in the state of operating about 100 Cyber Universities. Also, in the case of Hanam University, the Distant Learning classes are at its final stage of being established; this is a link in the rapid speed project of setting an example by the Korean Government. In addition, the department of education has selected 5 universities, including Seoul Cyber Design University for experimentation and is in the stage of strategic operation. Over 100 universities in Korea are speeding up its preparation for operating Cyber University. This form of Distant Learning goes beyond the walls of universities and is in the trend of being diffused in business areas or in various training programs of financial organizations and more. Here, in the hope that this material would some what be of help to other Universities which are preparing for Cyber University, I would 1ike to introduce some general concepts of the components forming Cyber University and Open Education System which has been established by JUNAM University. System of Cyber University could be seen as a general solution offered by tile computer technologies for the management on the students, Lectures On Demand, real hour based and satellite classes, media product ion lab for the production of the multimedia Contents, electronic library, the Groupware enabling exchange of information between students and professors. Arranging general concepts of components in the aspect of Cyber University and Open Education, it would be expressed in the form of the establishment of Cyber University and the service of Open Education as can be seen in the diagram below.

• Journal of forensic and investigative science
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• v.2 no.1
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• pp.5-22
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• 2007

From the numerous social problems generated by the unbalanced social development and the social trend of belittling life overall, we found the causes of suicide getting worse in its seriousness day by day. In reality, the problem has been approached in a collateral level in contrast with other social problems. There have been an active involvement in studying the definition, causes and ways of prevention of suicide theoretically until now. However, different from other social problems, it is almost impossible to treat or fix the problem of suicide. Only ways to treat or fix the problem is when the suicide has ended in failure. Thus, this study intends to examine the suicide rate among the total accidents during the year 2005, perform the analyses on the actual causes according to the relations such as the means of suicide, occupation, age group, educational background, etc. In order to present a solution to the issue of suicide becoming serious each day. Among the total accidents in 2005, the suicide rate came out to be approximately 52.4%. Among the result, 52.4%, male with 69% resulted higher than female with 31%, which appears to be related to the social functions. While men tends to take more active(80%) means of suicide like jumping off, poison, hanging, etc., women tends to take more passive(60%) means of suicide like sleeping pills, slitting wrist, etc. In terms of the cause, pessimism, illness, denial, mental disorder, etc resulted more than 75%, and there were many cases of suicide after exhibiting the signs of depression. Also there were higher suicide rate of the unemployed engaged in direct labor with educational background lower than college level related to the pessimism regarding the family living cost. We were able to determine the recent increase in the suicidal tendency of the educated people higher than the college level and the retired people with depression caused by the sudden change in social status. Overall there are several reasons for suicide, however, in most cases the signs of depression were exhibited until the final suicide, which tells us the serious psychological problem of suicide. Assuming that the current development of suicide will continue in future, the result of this study will guide the corresponding social policies, be utilized in preparing the insurance or management at the national level dealing with the real social problems that are not just a conflict of an individual, but could spread like a fad and become much bigger than the present by the continuous support at the environmental, social and political levels, and be utilized as the basic data to establish the research plan.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.3
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• pp.63-71
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• 2022

In this study, the interfacial reaction and drop impact reliability of Sn-Ag-Cu (SAC) solder and electroless nickel autocatalytic gold (ENAG) were studied. In addition, the solder joint properties with the ENAG surface finish was compared with electroless nickel immersion gold (ENIG) and electroless nickel electroless palladium immersion gold (ENEPIG). The IMC thickness of SAC/ENAG and SAC/ENEPIG were 1.15 and 1.12 ㎛, respectively, which were similar each other. The IMC thickness of the SAC/ENIG was 2.99 ㎛, which was about two times higher than that of SAC/ENAG. Moreover, it was found that the IMC thickness of the solder joint was affected by the metal turnover (MTO) condition of the electroless Ni(P) plating solution, and it was found that the IMC thickness increased when the MTO increased from 0 to 3. The shear strength of SAC/ENEPIG was the highest, followed by SAC/ENAG and SAC/ENIG. It was found that when the MTO increased, the shear strength was lowered. In terms of brittle fracture, SAC/ENEPIG was the lowest among the three joints, followed by SAC/ENAG and SAC/ENIG. Likewise, it was found that as MTO increased, brittle fracture increased. In the drop impact test, it was confirmed that the 0 MTO condition had a higher average number of failures than the 3 MTO condition, and the average number of failures was also higher in the order of SAC/ENEIG, SAC/ENAG, and SAC/ENIG. As a result of observing the fracture surface after the drop impact, it was found that the fracture was between the IMC and the Ni(P) layer.

• Journal of Chest Surgery
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• v.39 no.12 s.269
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• pp.879-890
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• 2006

Background: The dysfunction of multiple organs is found to be caused by reactive oxygen species as a major modulator of microvascular injury after hemorrhagic shock. Hemorrhagic shock, one of many causes inducing acute lung injury, is associated with increase in alveolocapillary permeability and characterized by edema, neutrophil infiltration, and hemorrhage in the interstitial and alveolar space. Aggressive and rapid fluid resuscitation potentially might increased the risk of pulmonary dysfunction by the interstitial edema. Therefore, in order to improve the pulmonary dysfunction induced by hemorrhagic shock, the present study was attempted to investigate how to reduce the inflammatory responses and edema in lung. Material and Method: Male Sprague-Dawley rats, weight 300 to 350 gm were anesthetized with ketamine(7 mg/kg) intramuscular Hemorrhagic Shock(HS) was induced by withdrawal of 3 mL/100 g over 10 min. through right jugular vein. Mean arterial pressure was then maintained at $35{\sim}40$ mmHg by further blood withdrawal. At 60 min. after HS, the shed blood and Ringer's solution or 5% albumin was infused to restore mean carotid arterial pressure over 80 mmHg. Rats were divided into three groups according to rectal temperature level($37^{\circ}C$[normothermia] vs $33^{\circ}C$[mild hypothermia]) and resuscitation fluid(lactate Ringer's solution vs 5% albumin solution). Group I consisted of rats with the normothermia and lactate Ringer's solution infusion. Group II consisted of rats with the systemic hypothermia and lactate Ringer's solution infusion. Group III consisted of rats with the systemic hypothermia and 5% albumin solution infusion. Hemodynamic parameters(heart rate, mean carotid arterial pressure), metabolism, and pulmonary tissue damage were observed for 4 hours. Result: In all experimental groups including 6 rats in group I, totally 26 rats were alive in 3rd stage. However, bleeding volume of group I in first stage was $3.2{\pm}0.5$ mL/100 g less than those of group II($3.9{\pm}0.8$ mL/100 g) and group III($4.1{\pm}0.7$ mL/100 g). Fluid volume infused in 2nd stage was $28.6{\pm}6.0$ mL(group I), $20.6{\pm}4.0$ mL(group II) and $14.7{\pm}2.7$ mL(group III), retrospectively in which there was statistically a significance between all groups(p<0.05). Plasma potassium level was markedly elevated in comparison with other groups(II and III), whereas glucose level was obviously reduced in 2nd stage of group I. Level of interleukine-8 in group I was obviously higher than that of group II or III(p<0.05). They were $1.834{\pm}437$ pg/mL(group I), $1,006{\pm}532$ pg/mL(group II), and $764{\pm}302$ pg/mL(group III), retrospectively. In histologic score, the score of group III($1.6{\pm}0.6$) was significantly lower than that of group I($2.8{\pm}1.2$)(p<0.05). Conclusion: In pressure-controlled hemorrhagic shock model, it is suggested that hypothermia might inhibit the direct damage of ischemic tissue through reduction of basic metabolic rate in shock state compared to normothermia. It seems that hypothermia should be benefit to recovery pulmonary function by reducing replaced fluid volume, inhibiting anti-inflammatory agent(IL-8) and leukocyte infiltration in state of ischemia-reperfusion injury. However, if is considered that other changes in pulmonary damage and inflammatory responses might induce by not only kinds of fluid solutions but also hypothermia, and that the detailed evaluation should be study.