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Million Gerado Geda,Tat-Thang LE,Sunju Kim,Kihoon Kim,Huu-Phuc Kieu,Sewan Choi 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-
This article presents a modulation scheme for achieving high-efficiency and high-power quality based on the secondary duty cycle and the phase shift for a single-stage electrolytic capacitor-less bidirectional onboard charger. Zero voltage switching is achieved for all switches for wide voltage range operation based on an optimized duty cycle which increased the efficiency of the converter. Meanwhile, high power quality is guaranteed by a varying phase shift which is directly generated by a controller. To validate the proposed modulation scheme, experimental results from the 3.7kW onboard charger are provided at 1kW power showing an improvement of 0.4% over the conventional method. Furthermore, the efficiency of the converter is improved by 3% at low battery voltage where zero voltage switching is severe while using the conventional method.
밀리언 테스파예(Million Tesfaye),하센 베시르(Hassen Beshir) 영남대학교 박정희새마을연구원 2018 새마을학연구 Vol.3 No.2
이 연구의 기본 목적은 에티오피아 오로모(Oromo) 지역 농촌가구의 생계에 미치는 소규모 관개의 영향을 분석하는 데 있다. 본 연구는 기본적으로 3단계 표본추출 과정을 통해 선정된 381명의 응답자로부터 확보된 자료를 분석했으며, 그 외에 2차 자료에도 의존하였다. 소규모 관개에 참여하는 것이 가구소득에 어떤 영향을 미치는지를 분석하기 위해 기술통계와 헤크만의 2단계 추정법을 활용했다. 프로비트 모델 분석의 결과에 따르면, 교육수준, 가축소유, 노동력, 가장 가까운 시장 중심지, 생산적 자산의 소유, 건강상태 등이 소규모 관개 계획에 참여 여부를 결정짓는 중요한 변인인 것으로 나타났다. 또한 두 단계로 이루어진 헤크만 모델의 측정 결과는 잠재적 변인들이 가구소득에 영향을 미친다는 것을 보여주었다. 한편 가구소득에 영향을 미치는 주요 변인으로는 관개 참여, 관개 가능한 경작지, 교육수준, 가축소유, 노동력, 천수답, 가장 가까운 시장 중심지, 가까운 전천후 도로, 생산적 자산 소유, 건강상태 등인 것으로 밝혀졌다. 계량경제학적 분석 결과는 관개에 참여하는 것이 농가의 가구소득에 중요하고도 긍정적인 효과를 가져다주며, 더 나아가 농가의 생계를 크게 향상시킨다는 것을 보여주었다. 따라서 전략가, 정책수립자, 개발관련 종사자들은 농촌 가구들이 관개농업에 더 많이 참여하도록, 그리고 이를 통해 농가의 생계를 향상시킬 수 있도록 위의 여러 변인들에 주목할 필요가 있다. The main goal of the study was to examine the impacts of small-scale irrigation on the livelihood of rural farm households in Oromo zone, Ethiopia. The study employed adequate and reliable facts obtained from 381 respondents selected through a three stage sampling procedures. The study mainly relied upon primary data and accompanied by secondary sources. Descriptive statistics and Heckman two-stage econometric estimation were used to identify contributing factor of small-scale irrigation participation and household income. Based on the probit result, education level, livestock holding, labor force, nearest market center, productive asset holding and health condition were significant determinant variables that influence involvement in small-scale irrigation schemes. Outcomes of Heckman model observed in the second stage revealed the potential variables influence household income. The important variables that influence family earnings include irrigation participation, irrigable cultivated land, education level, livestock holding, labor force, rain-fed cultivated land, nearest market center, nearest all-weather road, productive asset holding and health condition. The econometric results confirmed that participation in irrigation had a considerable and progressive effect on farm households’ income and in turn profoundly improved rural household livelihood. Thus, strategists, policy makers and development actors should give due emphasis to the abovementioned variables to increase participation in irrigation farming and ultimately to improve the livelihood of rural households.
Effect of Pretreatment of Mine Tailings on the Performance of Controlled Low Strength Materials
밀리언 타페세,김형기,Tafesse, Million,Kim, Hyeong-Ki The Korean Institute of Resources Recycling 2017 資源 리싸이클링 Vol.26 No.3
광산 부산물인 광미를 건설용으로 대량활용하기 위해서는 내부의 중금속을 제거하기 위한 전처리가 필요하다. 본 연구에서는 전처리 된 광미를 필러(Filler)로 혼입한 저강도 고유동 충전재(Controlled low strength material, CLSM)의 성능에 대해 실험적으로 평가하였다. 전처리가 충전재의 저 성능에 미치는 영향을 평가하기 위해서 전처리 되지 않은 광미 이외에도 고주파 가열 처리, 고주파 가열 후 자력선별 처리한 광미를 실험에 사용하였다. 시멘트의 혼입량은 광미 질량의 10%, 20%, 30%로 설정하였다. 배합설계한 모든 충전재는 미국 콘크리트학회의ACI Committee 229에서 제시한 유동성 200 mm 이상 및 강도 0.3-8.3 MPa의 기준을 만족하는 동시에 최종 침하량은 1% 이하임을 확인하였다. For the massive recycling of mine tailings, which are an inorganic by-product of mining process, in the field of civil engineering, pretreatments to extract heavy metals are required. This study focuses on the use of pre-treated tailings as substitute fillers for controlled low-strength material (CLSM). As a comparative study, untreated tailing, microwave-treated tailing and magnetic separated with microwaved tailing were used in this study. Cement contents amounting to 10%, 20% and 30% by the weight of the tailings were designed. Both compressive strength and flowability for all types of mixture were satisfied with the requirements of the American Concrete Institute (ACI) Committee 229, i.e., 0.3-8.3 MPa of compressive strength and longer than 200 mm flowability. Furthermore, all mixtures showed settlements less than 1% by volume of the mix.
Sunju Kim,Kunwoo Kang,Million Gerado Geda,Huu-Phuc Kieu,Sewan Choi,Suchang Lee,Juhwan Yun,Jungpil Park 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-
This paper proposes a high-efficiency modulation scheme and magnetic integration for single-stage microinverter module-level power electronics. The proposed 400W microinverter achieves full zero voltage switching for dc input voltages ranging from 18V to 58V, using a half bridge matrix-based DAB structure. The proposed switching modulation method is easy to control and enables high power density due to the use of a constant switching frequency. In addition, the integration of transformer and series inductor reduced the volume of the converter by 18%, and power loss by 50% of separated cores. To validate the proposed method, a 400W micro-inverter prototype was built and achieved a peak efficiency of 97.33% and a CEC efficiency of 96.58%.
Pyo, Sukhoon,Tafesse, Million,Kim, Bong-Ju,Kim, Hyeong-Ki Elsevier 2018 Construction and Building Materials Vol.166 No.-
<P><B>Abstract</B></P> <P>High production cost and scarcity of raw materials may hinder the application and accessibility of ultra-high performance concrete (UHPC). In the present study, mine tailings, mineral waste products from mining sites, were applied to mitigate these problems. Two types of quartz-based mine tailings produced in South Korea were used to substitute silica powder and silica sand by half and fully in UHPC. The characteristics of UHPC with the tailings, including the compressive strength, workability, water absorption, and leachability of toxic elements, were experimentally evaluated. The effects of the tailings on the characteristics of UHPC varied according to the shape and size of particles of the tailings. The leaching of toxic trace elements from the tailings was highly controlled due to the chemical and physical capsulation of UHPC.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mine tailings could substitute silica powder and sand in UHPC. </LI> <LI> Characteristics of UHPC were varied by the shape and size of tailings. </LI> <LI> Leaching of toxic elements in tailings was highly controlled by UHPC matrix. </LI> </UL> </P>
( Yvette Tache ),( Mulugeta Million ) 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2015 Journal of Neurogastroenterology and Motility (JNM Vol.21 No.1
The corticotropin-releasing factor (CRF) signaling systems encompass CRF and the structurally related peptide urocortin (Ucn) 1, 2, and 3 along with 2 G-protein coupled receptors, CRF1 and CRF2. CRF binds with high and moderate affinity to CRF1 and CRF2 receptors, respectively while Ucn1 is a high-affinity agonist at both receptors, and Ucn2 and Ucn3 are selective CRF2 agonists. The CRF systems are expressed in both the brain and the colon at the gene and protein levels. Experimental studies established that the activation of CRF1 pathway in the brain or the colon recaptures cardinal features of diarrhea predominant irritable bowel syndrome (IBS) (stimulation of colonic motility, activation of mast cells and serotonin, defecation/watery diarrhea, and visceral hyperalgesia). Conversely, selective CRF1 antagonists or CRF1/CRF2 antagonists, abolished or reduced exogenous CRF and stress-induced stimulation of colonic motility, defecation, diarrhea and colonic mast cell activation and visceral hyperalgesia to colorectal distention. By contrast, the CRF2 signaling in the colon dampened the CRF1 mediated stimulation of colonic motor function and visceral hyperalgesia. These data provide a conceptual framework that sustained activation of the CRF1 system at central and/or peripheral sites may be one of the underlying basis of IBS-diarrhea symptoms. While targeting these mechanisms by CRF1 antagonists provided a relevant novel therapeutic venue, so far these promising preclinical data have not translated into therapeutic use of CRF1 antagonists. Whether the existing or newly developed CRF1 antagonists will progress to therapeutic benefits for stress-sensitive diseases including IBS for a subset of patients is still a work in progress.