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Comparison of Gap Pressure in Opening Wedge High Tibial Osteotomy versus Compressive Strength of Allogenous Wedge Bone Blocks (경골 근위부 개방 절골술 시 개방부 압력과 동종 쐐기 골편의 최대압축하중 비교)

  • Yoon, Kyoung Ho;Kim, Jung Suk;Kwon, Yoo Beom;Kim, Eung Ju;Lee, Myeong-Kyu;Kim, Sang-Gyun
    • Journal of the Korean Orthopaedic Association
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    • v.55 no.2
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    • pp.127-134
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    • 2020
  • Purpose: The aims of this study were (1) to investigate the relationship between the characteristics of allogenic bone block and the compressive strength of an allogenic bone block measured by biomechanical experiments, and (2) to compare the maximum pressure load of allogenic bone block with the gap pressure measured at the high tibial opening osteotomy. Materials and Methods: Ten patients who provided informed consent for gap pressure measurements during opening wedge high tibial osteotomy (OWHTO) were included. The gap pressures were measured at 1 mm intervals while opening the osteotomy site from 8 mm to 14 mm. Seventeen U-shaped allogenous wedge bone blocks were made from the femur, tibia, and humerus. The height, width, cross-sectional area, and cortex thickness of the bone blocks were measured, along with the maximum compressive load just before breakage. The relationship between these characteristics and the maximum pressure load of the bone blocks was evaluated. The gap pressures measured in OWHTO were compared with the maximum pressure loads of the allogenous wedge bone blocks to evaluate the possibility of inserting allogenous wedge bone blocks into the osteotomy site without a distractor in OWHTO. Results: The OWHTO gap pressure increased with increasing osteotomy site opening. The mean gap pressure, which occurred at a 14-mm opening, was 282±93 N; the maximum pressure was 427 N. The maximum pressure load of the allografts was 13,379±6,469 N (minimum, 5,868; maximum, 29,130 N) and was correlated significantly with the cortical bone thickness (correlation coefficient=0.693, p=0.002) and cross-sectional area (correlation coefficient=0.826, p<0.001). Depending on the sterilization method, the maximum pressure loads for the bone blocks were 13,406±5,928 N for freeze-dried and 13,348±7,449 N for fresh frozen. The maximum compressive load of the allogenous wedge bone blocks was 13.7-times greater than that in OWHTO opened to 14 mm (5,868 N vs. 427 N). Conclusion: The compressive strength of allogenous wedge bone blocks was sufficiently greater than the gap pressure in OWHTO. Therefore, allogenous wedge bone blocks can be inserted safely into the osteotomy site without a distractor.

A 40-year History of the Asia Pacific Journal of Small Business : Small and Medium Venture Business Policy and Strategic Management of Small and Medium Venture Businesses (중소기업연구 40년의 역사: 중소벤처기업정책 및 중소벤처기업의 전략적 경영)

  • Seo, Won-Seok;Lee, Sang-Myung
    • Korean small business review
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    • v.42 no.3
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    • pp.101-121
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    • 2020
  • Marking the 40th anniversary of the founding of The Korean Association of Small Business Studies, this paper was carried out to shed light on the historical trend of 40 years of small and medium business research through the papers published in the Asia Pacific Journal of Small Business and to consider the direction of future small and medium business research. In particular, we will focus on small and medium venture business policies and strategic management aspects of small and medium venture businesses to analyze the contents of published papers related to the subject and contribute to finding implications and future research directions. In order to analyze the research trends of small and medium venture business policies and strategic management sectors of small and medium venture companies covered in the Asia Pacific Journal of Small Business from 1979 to 2019, the analysis was divided by time and item based on research subjects, research methods, researchers, etc., and the primary analysis results are as follows: First, out of a total of 1,056 research papers, research papers on small and medium venture enterprise policy and strategic management showed a ratio of about 14% and 11% of the total research. Second, in terms of research subjects, the proportion of policy research on funds and start-ups and ventures was high in the field of small and medium venture enterprise policy, and the research on internationalization strategy was carried out the most in the area of strategic management. Third, qualitative research was more prominent until the 1980s, but the proportion of quantitative research began to increase after the 1990s, and since then, quantitative research has been carried out more than qualitative research. Fourth, over the past 40 years, Hanyang University, Kyungpook National University, Konkuk University, etc. were the institutions that presented research papers most actively in the areas of small and medium venture business policy and strategic management, and the research institute's participation was somewhat insufficient. The main implications of this study for the continuous development of the Asia Pacific Journal of Small Business are as follows. First, it is necessary to enhance the link between research on policy research and strategic management of small and medium venture companies in terms of research subject matter. Second, more diversity should be pursued in terms of research methods. Third, it is necessary to increase the participation rate of public and private research institutes related to small and medium venture enterprises in academic societies.

Chronopolitics in the Cinematic Representations of "Comfort Women" (일본군 '위안부'의 영화적 기억과 크로노폴리틱스)

  • Park, Hyun-Seon
    • Journal of Popular Narrative
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    • v.26 no.1
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    • pp.175-209
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    • 2020
  • This paper examines how the cinematic representation of the Japanese military "comfort women" stimulates 'imagination' in the realm of everyday life and in the memory of the masses, creating a common awareness and affect. The history of the Japanese military "comfort women" was hidden for a long time, and it was not until the 1990s that it entered the field of public recognition. Such a transition can be attributed to the external and internal chronopolitics that made possible the testimony of the victims and the discourse of the "comfort women" issue. It shows the peculiar status of the comfort women history as 'politics of time'. In the same vein, the cinematic representations of the Japanese military "comfort women" can be found in similar chronopolitics. The 'comfort women' films have shown the dual time frame of the continuity and discontinuity of the 'silence'. In Korean film history, the chronotope of the reproduction of "comfort women" can be divided into four phases: 1) the fictional representations of "comfort women" before the 1990s 2) documentaries in the late 1990s as the work of testimony and history writing, 3) melodramatic transformation in the feature films in the 2000s, and 4) the diffusion of media and categories. The purpose of this article is to focus on the first phase and the third phase in which the issue of 'comfort women' is represented in the category of popular fiction films. While the "comfort women" representations before 1990 were strictly adhering to the framework of commercial movies and pursued the sexual exploitation of "comfort women" history, the recent films since the 2000s are experimenting with various attempts in the style of popular imagination. Especially, the emergence of 'comfort women' feature films in the 2000s, such as Spirit's Homecoming, I Can Speak, and Herstory, raise various questions as to whether we are "properly" aware of issues and how to remember and present the "cultural memory" of comfort women. Also, focusing on the cinematic representation strategies of the 2000s "comfort women", this article discusses the popular politics of melodrama, the representation of victims and violence, and the feature of 'comfort women' as meta-memory. As a melodramatic imagination and meta-memory for the historical trauma, the "comfort women" drama shows the historical, political, and aesthetic gateways to which the "comfort women" problem must pass. As we have seen in recent fiction films, the issue of "comfort women" goes beyond transnational relations between Korea and Japan; it demands a postcolonial task to dismantle the old colonial structure and explores a transnational project in which women's movements and human rights movements are linked internationally.

Improving the Current Status and Cultural Value of Donguibogam Wanyoung Woodblocks (<동의보감(東醫寶鑑)> 완영(完營)책판의 현황과 문화재적 가치 제고(提高))

  • KIM, Hwaseon
    • Korean Journal of Heritage: History & Science
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    • v.55 no.2
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    • pp.50-64
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    • 2022
  • This thesis is a study on the woodblock of Donguibogam by Jeolla Gamyeong(Wanyoung Woodblock). It was registered as a tangible cultural property in Jeollabuk-do in 2005. The purpose of this article is to determine the current status and value of the Donguibogam Wanyoung Woodblock. Jeonju Hyanggyo's Wanyoung Woodblock was used to print books in Gamyeong, Jeolla Province. Currently, ten kinds of woodblocks are preserved. In 1987, a wooden bookshelf was installed and preserved in "Jangpangak" of Jeonju Hyanggyo. It is now preserved and managed at Chonbuk National University Museum. Among the ten woodblocks, the Wanyoung woodblock of Donguibogam is presumed to be a woodblock of a book printed by Jeolla Gamyeong in 1814. The value of Donguibogam has long been recognized domestically and internationally. Donguibogam, compiled in 1610, was first published in 1613 in the wood type of Gaeju Gapinja. Following its publication, its value was recognized not only in Joseon but also in China and Japan. In 2009, the first edition of Donguibogam was registered as a UNESCO World Heritage. Accordingly, Donguibogam has been recognized for various aspects, but little research has been conducted on the woodblocks that printed Donguibogam. Therefore, this paper analyzes the current status of the Wanyoung woodblock of Donguibogam, aiming to enhance its meaning and value. King Seonjo presented the ideals of public health care and preventive medicine when compiling Donguibogam, which was distributed according to his instructions. For this reason, the first edition of Donguibogam was registered as a UNESCO World Heritage. It can be said that the production of Donguibogam woodblocks was an important tool in realizing Joseon's ideals through national dissemination. Furthermore, the woodblock of Donguibogam represents the spirit of thinking about the people, going beyond the purpose of printing, and it was meaningful in the spread of medical knowledge among the people. In this article, I will examine the overall contents of the Wanyoung woodblock of Donguibogam to enhance its meaning and value. The results show that the Wanyoung woodblock of Donguibogam is meaningful in that it is almost the only one produced and stored by Gamyeong. Moreover, Wanyoung woodblocks are meaningful in that perfect editions could be preserved and disseminated for a long time, unlike other wood-type prints.

Analysis of Soil Changes in Vegetable LID Facilities (식생형 LID 시설의 내부 토양 변화 분석)

  • Lee, Seungjae;Yoon, Yeo-jin
    • Journal of Wetlands Research
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    • v.24 no.3
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    • pp.204-212
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    • 2022
  • The LID technique began to be applied in Korea after 2009, and LID facilities are installed and operated for rainwater management in business districts such as the Ministry of Environment, the Ministry of Land, Infrastructure and Transport, and LH Corporation, public institutions, commercial land, housing, parks, and schools. However, looking at domestic cases, the application cases and operation periods are insufficient compared to those outside the country, so appropriate design standards and measures for operation and maintenance are insufficient. In particular, LID facilities constructed using LID techniques need to maintain the environment inside LID facilities because hydrological and environmental effects are expressed by material circulation and energy flow. The LID facility is designed with the treatment capacity planned for the water circulation target, and the proper maintenance, vegetation, and soil conditions are periodically identified, and the efficiency is maintained as much as possible. In other words, the soil created in LID is a very important design element because LID facilities are expected to have effects such as water pollution reduction, flood reduction, water resource acquisition, and temperature reduction while increasing water storage and penetration capacity through water circulation construction. In order to maintain and manage the functions of LID facilities accurately, the current state of the facilities and the cycle of replacement and maintenance should be accurately known through various quantitative data such as soil contamination, snow removal effects, and vegetation criteria. This study was conducted to investigate the current status of LID facilities installed in Korea from 2009 to 2020, and analyze soil changes through the continuity and current status of LID facilities applied over the past 10 years after collecting soil samples from the soil layer. Through analysis of Saturn, organic matter, hardness, water contents, pH, electrical conductivity, and salt, some vegetation-type LID facilities more than 5 to 7 years after construction showed results corresponding to the lower grade of landscape design. Facilities below the lower level can be recognized as a point of time when maintenance is necessary in a state that may cause problems in soil permeability and vegetation growth. Accordingly, it was found that LID facilities should be managed through soil replacement and replacement.

A Study on Status of Landscape Architecture Industry with National Statistics (국가통계자료를 활용한 조경산업 현황 연구)

  • Choi, Ja-Ho;Yoon, Young-Kwan;Koo, Bon-Hak
    • Journal of the Korean Institute of Landscape Architecture
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    • v.50 no.5
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    • pp.40-53
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    • 2022
  • This study carried out to provide the methodology and basic status material of using Korean national statistics needed to find the actual state of the landscape architecture industry. The landscape architecture industry was classified into 'Design', 'Construction Management', 'construction', 'Maintenance & Management', 'Materials', 'Research', 'Education', and 'Administration' areas. In each field, business types were systemized and associated in accordance with Korean standard industrial classification and legislations pertinent to construction. Among them, the business types directly defined in the construction related legislations under the Ministry of Land, Infrastructure and Transport were focused on, and the establishment, association, integration, distribution, duplication, and omission of national statistics were analyzed. As a result, the business types of statistical analysis were selected. In order for commonality of statistical items and minimized error of interpretation, semantic analysis was conducted. Finally, the number of registered business types, the number of workers, and sales were selected. Based on them, the analysis framework applicable to fundamental analysis and evaluation of the actual state of the industry was proposed. Actual national statical data were applied for analysis and evaluation. In 2019, the number of registered business types related to the landscape architecture industry was 12,160, the number of workers by business type was 106,296, and the sales by business type were 8,308.5 billion KRW. The number of registered business types and the number of workers had been on the rise from 2017, whereas the sales had been on the decrease. It is required to come up with a plan for industrial development. This study was conducted with the national statistics established by multiple public institutions, so that there are limitations in securing consistency and reliability. Therefore, it is necessary to establish systematic and consistent national statistics in accordance with 「Landscaping Promotion Act」. In the future, it will planned to research application and development plans of national statistics according to subjects including park and green.

Health Promotion Through Healthy People 2010 ("2010년대 건강한 시민" 정책을 통한 미국의 건강증진 방향)

  • Cho, Jung H.
    • Proceedings of The Korean Society of Health Promotion Conference
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    • 2004.10a
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    • pp.17-58
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    • 2004
  • 뉴저지주 보건교육/건강 증진정책을 논하기전에 건강증진과 보건 교육사의 뜻을 먼저 기술하기로 한다. 건강증진이란 일상 사회생활과 행동과학의 응용에서 시작하며 교육의 효율적 작전 및 기술, 질병 역학 조사, 개인 및 가족단위 건강 위해 행위 절감, 사회연관 구축망 조성, 그리고 적게는 이웃, 더 나아가 조직체계 및 지역 사회의 네트웍 실시등을 실시한다. 보건교육 및 건강증진 전문가란 ' 전국 보건교육 인증 위원회(NCHEC) ' 에서 채택된 다음 7개 활동 영역에서 개인적, 그룹, 각주단위, 그리고 범 국가적 조직에서 종사하는자로 한다. 개인 및 지역사회 보건 교육 필요성 분석- 계회, 실행, 효율성 평가, 사업 진행 조정, 자문, 컴뮤니케이션 등의 활동범위를 들 수 있다. 공인 보건 교육사(CHES)란 대학 및 대학원에서 보건 교육학 소정의 필수 과목을 이수하고 학.석사 소지자로서 ' 전국 보건 교육 인증 위원회 ' 에서 그 자격을 인정 받고 공인 자격 시험에 합격한자로 한다. 합격자는 자기 성명뒤에 CHES란 칭호를 부치며 매 5년마다 75단위이상 인정된 전문 직업 보수 교육을 받아야 한다. 보건 교육사 고용 분야는 연방, 주, 지방 정부의 보건 교육사(10-15%) 및 건강 증진 전문가로 종사하며; 이들은 지역 사회 조직화, 프로그람 기획, 공공사업 마켓팅, 메디아, 컴뮤니케이션 자질을 갓추어야 하며; 상해 예방, 학교 보건, 지역 사회 영양 실태 향상, 그 외 모든 건강 증진과 질병 예방에 일익을 담당 하여; 의사, 간호사, 약사, 영양사,환경 위생사드의 전문분야종사자들괴 한팀이 되어 지역 사회 보건 사업에 기여한다. 쥬저지 보건 교육사들은 주법령 8조 '||'&'||' 보건행정 표준 시행령 ' 에 따라 포괄적 보건교육/건강증진 프로그램을 개발하여 총체적으로 조절 관장한다. 특희 ' 미국 학술원 의료 연구원 ' 에서 제정한 ' 10대 필수 공중 보건 사업 ' 에 기준을 두고; 1) 개인 및 지역사회 필수 보건 여건 분석 평가, 2) 보건 교육 이론에 따른 사업 계획 설정, 3) 교육 전략과 보건문제 발굴에 따라 일반 대중 대상 보건 교육 실행 (프로그람 기획, 연수 교육, 미디어 캠페인, 공중보건 향상책 옹호), 4) 사업 진행 과정 정리, 그 결과에 대한 영향력과 결과 평가, 5) 프로그램진행, 인사 및 예산관리 참여, 6) 근무향상을 위한 보수교육 프로그램 개발, 7) 보건 의료 업무 종사자 상호 협조성 향상 훈련, 8) 지역 사회자원 밭굴, 9) 적절한 고객 의뢰 체제 시행, 10) 위기 관리 컴뮤니케이션 체제 개발실시, 11) 일반 대중에게 공중 보건 향상 고취, 12) 각종 협력 지원금 신청서 작성 제출, 13) 문화/인종적으로 적절한 시청각 교재 발굴, 15) 질적 및 양적 보건교육/건겅증진책 연구 실시, 16) 비 보험 가담자, 저 보험자, 빈곤자, 이민자 색출 선도, 17) 관활 구역내 상재하는 각 건강증진 프로그램 밝혀 내서 불필요한 중복 회피등이다. 그 외에도 보건 교육사들은 사회 복지 단체인 미국 암 협회, 미국 심장 협회,미국 폐장 협회 등 각종 사회 복지 비영리단체 와 자선 사업 단체들과 긴밀희 협조하거나 그 단체 임직원으로서 건강 증진 사업에 종사한다. 병원 및 의료기관에선 임직원 보수 교육, 환자의 질병 예방및 건강증진 교육, 그리고 의료 사업장내 건장 증진업무에 종사한다. 건강 유지 의료 기관(HMO)에선 예방주사, 정기검진 촉진등을 통한 입원일수 절감, 응급실 사용도 절감등으로 의료비 감축, 삶의질 향상상에 종사한다. 사업장 보건 교육사는 스트레스 관리, 금연 및 흡연 중단선도, 체중 절감, 종업원 건강증진 생활화참여 유치, 컴뮤니케이션 개발, 마켓팅, 질병 예방등에 그 전문 직업적 노하우를 사업체 건강 증진 프로그램 개발에 접목한다. 뉴저지 2010년대 건강 증진책은 5대 목표 설정하여 현재 시행하고 있다. 특이한점은 2001년 9.11사태 이후 연방정부와 주정부의 상당한 예산 지원을 그랜트 지원금 형식으로 받아 연방, 주정부, 지방 정부, 의료 기관등에서 일사 불란하게 생물/화학/방사성 테러에 대비하는데 보건 교육사들은 시민 인지도 향상과 위기관리 컴뮤니케이션 영역에서 활약한다. 총체적인 보건 교육/건강 증진책은 다음 천년간 뉴저지 건강증진 백서와 미연방 정부 건강증진 2010에 준하여 설립한 뉴저지 건강 증진 2010 에 의한다. 그 모델을 보면; 1) 생활 습관 향상으로 위해 행위 절제; 적절한 영양 섭취 와 과체중화 차단 불필요한 투약 절제와 그 관리 흡연 탐익 절감, 금연, 흡연관련 신체/정신적 피해 관리/치료 습관성 약물 중독 조기발견 예방 낙상 예방 폭력, 의도적/비의도적 상해 예방 2) 심장질환, 암, 뇌졸중, 당뇨, 폐염, 인프루엔자등 주사망원인 질병 조기 발견 예방 책 마련; 독감.폐렴 예방 주사 실시 3) 보건 교육 대상과 표적 설정 특히 보건사업 참여 동반자 발굴하여 그 동참과 책임분담 책려; 주. 지방 정부기관, 의료 종사자, 의료 보험 업자, 대학 등 교육 기관, 연구 기관, 교육자, 지방 보건소, 지역 사회 비 영리단체, 종교 단체 및 교역자 등의 참여 촉구., 지역 사회 비 영리단체, 종교 단체 및 교역자 등의 참여 촉구.

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Predicting the Effects of Agriculture Non-point Sources Best Management Practices (BMPs) on the Stream Water Quality using HSPF (HSPF를 이용한 농업비점오염원 최적관리방안에 따른 수질개선효과 예측)

  • Kyoung-Seok Lee;Dong Hoon Lee;Youngmi Ahn;Joo-Hyon Kang
    • Journal of Wetlands Research
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    • v.25 no.2
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    • pp.99-110
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    • 2023
  • Non-point source (NP) pollutants in an agricultural landuse are discharged from a large area compared to those in other land uses, and thus effective source control measures are needed. To develop appropriate control measures, it is necessary to quantify discharge load of each source and evaluate the degree of water quality improvement by implementing different options of the control measures. This study used Hydrological Simulation Program-FORTRAN (HSPF) to quantify pollutant discharge loads from different sources and effects of different control measures on water quality improvements, thereby supporting decision making in developing appropirate pollutant control strategies. The study area is the Gyeseong river watershed in Changnyeong county, Gyeongsangnam-do, with agricultural areas occupying the largest proportion (26.13%) of the total area except for the forest area. The main pollutant sources include chemical and liquid fertilizers for agricultural activities, and manure produced from small scale livestock facilities and applied to agriculture lands or stacked near the facilities. Source loads of chemical fertilizers, liquid fertilizers and livestock manure of small scale livestock facilities, and point sources such as municipal wastewater treatment plants (WWTPs), community WWTPs, private sewage treament plants were considered in the HSPF model setup. Especially, NITR and PHOS modules were used to simulate detailed fate and transport processes including vegitation uptake, nutrient deposition, adsorption/desorption, and loss by deep percolation. The HSPF model was calibrated and validated based on the observed data from 2015 to 2020 at the outlet of the watershed. The calibrated model showed reasonably good performance in simulating the flow and water quality. Five Pollutants control scenarios were established from three sectors: agriculture pollution management (drainge outlet control, and replacement of controlled release fertilizers), livestock pollution management (liquid fertilizer reduction, and 'manure management of small scale livestock facilities) and private STP management. Each pollutant control measure was further divided into short-term, mid-term, and long-term scenarios based on the potential achievement period. The simulation results showed that the most effective control measure is the replacement of controlled release fertilizers followed by the drainge outlet control and the manure management of small scale livestock facilities. Furthermore, the simulation showed that application of all the control measures in the entire watershed can decrease the annual TN and TP loads at the outlet by 40.6% and 41.1%, respectively, and the annual average concentrations of TN and TP at the outlet by 35.1% and 29.2%, respectively. This study supports decision makers in priotizing different pollutant control measures based on their predicted performance on the water quality improvements in an agriculturally dominated watershed.

A Comparative Study on Spiritual Humanism in Daesoon Thought (대순사상의 영성인본주의 비교연구)

  • Kim Yong-hwan
    • Journal of the Daesoon Academy of Sciences
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    • v.44
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    • pp.141-175
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    • 2023
  • This comparative study combines the methodologies of comparative research and literature review to examine Daesoon Thought. Comparative religious analysis in the social sciences, does not presuppose an a priori framework of the essence of religion because it targets various aspects of religion which are revealed within a historical field. However, it does not decompose and return to psychological or social phenomena like social sciences. In addition, with the emergence of religious pluralism, the climate of focusing on similarities between religions has already been accomplished to some degree. Furthermore, it is worth noting that many spiritual movements in modern spirituality reveal mixed or amorphous characteristics without being restricted by specific religious membership. It is time to overcome instrumentation and restore the transcendence of its original appearance even in secular humanist reasoning. It can be said that this reveals the perception that the ills and crises of modern civilization should be overcome in connection with the opening of the acquired world of Daesoon Thought. It could further be said that the main culprit of evil behavior is instrumental reason or degenerated reason rather than spirituality. Religion is the intellectual crystalline body of humankind and aims at human perfection and salvation. However, extremists in previous times amplified conflicts between religions and formed ideas suitable for their specific regions through different experiences. This generated mental rifts that proved greatly influential. At the time of initial inception, each religion confronted and fought other ideologies, but when the era of religious pluralism began, the necessity for inter-spiritual communication became urgent. It could be said that happiness is the realization of human spirituality by exploring the vision of humanism. In that case, the combined methodologies of comparative research and literature review reveal that the spirituality of Daesoon Thought would enable a humanism based on human dignity. This would be a path for seeking spirituality through human life and living as a true human being. Spiritual humanism as discussed through this study aims to share the problems of modern civilization and provide a critical view of modern civilization that shows the roots of prevailing thought are stuck in a Cartesian dualistic view of humanity and the world. The type of spiritual humanism to examined here focuses on a cosmotheandric vision by considering the spiritual return to Daoism via Daesoon Thought. This would treat human beings like heaven in alignment with Donghak ideology and honor the human dignity proposed by Daesoon Thought. It would also deliver sentient beings from suffering and to bliss in accordance with the aims of faith in Maitreya Buddha, and it would implement the Resolution of Grievances for Mutual Beneficence in fulfillment of Daesoon Thought.

Method of Reducing Separation Membrane Fouling Using Microbubbles (마이크로버블을 이용한 분리막 파울링 저감방법)

  • Kyung-Hwan Ku;Younghee Kim
    • Clean Technology
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    • v.29 no.1
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    • pp.31-38
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    • 2023
  • Due to water shortages caused by water pollution and climate change, total organic carbon (TOC) standards have been implemented for wastewater discharged from public sewage treatment facilities. Furthermore, there is a growing interest and body of research pertaining to the reuse of sewage treatment water as a secure alternative water resource. The membrane bio-reactor (MBR) method is commonly used for advanced wastewater treatment because it can remove organic and inorganic ions and it does not require or emit any chemicals. However, the MBR process uses a separation membrane (MF), which requires frequent film cleaning due to fouling caused by a high concentration of mixed liquor suspended solid (MLSS). In this study, process improvement and microbubble cleaning efficiency were evaluated to improve the differential pressure, water flow, and MF fouling, which are the biggest disadvantages of operating the MF. The existing MBR method was improved by installing a precipitation tank between the air tank and the MBR tank in which raw water was introduced. Microbubbles were injected into a separation membrane tank into which the supernatant water from the precipitation tank was introduced. The microbubble generator was operated with a 15 day on, 15 day off cycle for 5 months to collect discharged water samples (4L) and measure TOC. As the supernatant water from the precipitation tank flowed into the separation membrane tank, about 95% of the supernatant water MLSS was removed so the MF fouling from biological contamination was prevented. Due to the application of microbubbles to supernatant water from the precipitation tank, the differential pressure of the separation membrane tank decreased by 1.6 to 2.3 times and the water flow increased by 1.4 times. Applying microbubbles increased the TOC removal rate by more than 58%. This study showed that separately operating the air tank and the separation membrane tank can reduce fouling, and suggested that applying additional microbubbles could improve the differential pressure, water flow, and fouling to provide a more efficient advanced treatment method.