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Discharge Characteristics of Large-Area High-Power RF Ion Source for Positive and Negative Neutral Beam Injectors

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Plasma Science and Technology 2016年第12期18卷 1220-1224页

作者： Doo-Hee CHANG seung ho jeong Min PARK Tae-Seong KIM Bong-Ki JUNG Kwang Won LEE Sang Ryul IN Division of Nuclear Fusion Engineering & Technology Development Korea Atomic Energy Research Institute

A large-area high-power radio-frequency（RF） driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute（KAERI）. The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.

关键词： neutral beam injector RF ion source plasma ignition power loading plasma parameters

Influence of the wastewater composition on denitrification and biological P-removal in the S-DN-P process: (c) Dissolved and undissolved substrates

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Journal of Environmental Sciences 2009年第8期21卷 1074-1079页

作者： Hee-jeong Choi Chul-ho Choi seung-Mok Lee Diwakar Tiwari Department of Environmental Engineering Kwandong University Department of Chemistry School of Physical Sciences Mizoram University

The denitdfication and P-removal in the sorption-denitrification-P-removal （S-DN-P） process were carded out under various wastewater compositions. It is noted that P-removal largely depends on the wastewater composition as well to the quantity of the substrates present in wastewater fraction. Three different wastewater fractions are obtained as： raw wastewater, dissolved wastewater （obtained with filtration using 0.45 μm filter）, and undissolved wastewater （i.e., infiltrate obtained by above filtration）. The ratio of P-release/CODtotal-consumption clearly inferred that undissolved wastewater possess very low value i.e., 0.0008 followed by raw wastewater 0.008 and dissolved wastewater 0.03. When this ratio was nearby 0.01, enhanced P-removal was observed. Moreover, the ratio of P-uptake to NO3^--N decomposition for raw wastewater was two times for dissolved wastewater. Interestingly, it was observed that the P-removal and denitrification depend not only on the dissolved substrates but also the undissolved substrates present in the wastewater. The result of the P-removal obtained with this S-DN-P process did not show a big difference of 36%, 34% and 30%, respectively, for raw, dissolved and undissolved wastewater.

关键词： denitrification polyhydroxybutyrate sequencing batch biofilm reactor sorption denitrification P-removals

Application of Integrated Database to the Casting Design

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Journal of Materials Science & Technology 2008年第3期24卷 351-355页

作者： In-Sung Cho seung-Mok Yoo Chae-ho Lim jeong-Kil Choi KITECH 7-47 Songdo-dongYeonsu-gu

Construction of integrated database including casting shapes with their casting design, technical knowledge, and thermophysical properties of the casting alloys were introduced in the present study. Recognition tech- nique for casting design by industrial computer tomography was used for the construction of shape database. Technical knowledge of the casting processes such as ferrous and non-ferrous alloys and their manufacturing process of the castings were accumulated and the search engine for the knowledge was developed. Database of thermophysical properties of the casting alloys were obtained via the experimental study, and the properties were used for the in-house computer simulation of casting process. The databases were linked with intelligent casting expert system developed in center for e-design, KITECH. It is expected that the databases can help non casting experts to devise the casting and its process. Various examples of the application by using the databases were shown in the present study.

关键词： Integrated database Casting design Shape recognition

Influence of sulfides on the tribological properties of composites produced by pulse electric current sintering

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International Journal of Minerals,Metallurgy and Materials 2014年第1期21卷 95-103页

作者： seung ho Kim Department of Electronics Engineering Dankook University

Self-lubricating A1203-15wt% ZrO2 composites with sulfides, such as molybdenum disulfide （MoS2） and tungsten disulfide （WSz） serving as solid lubricants, were fabricated by using the pulse electric current sintering （PECS） technique. The coefficient of friction （COF） of the A1203-15wt% ZrO2 composite without/with sulfides was in the range of 0.37-0.48 and 0.27-0.49, respectively. As the amoant of sul- fides increased, the COF and the wear rate decreased. The reduction in COF and wear rate of the sulfide-containing composite is caused by a reduction in shear stresses between the specimen and the tribological medium due to the formation of a lubricating film resulting from the lamellar structure of sulfides located on the worn surface.

关键词： ceramic composites coefficient of friction solid lubricants sulfides wear of materials

Evaluation of defects in aluminum piston castings by using ultrasonics and computer tomography

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China Foundry 2012年第3期9卷 275-278页

作者： In-Sung Cho jeong-ho Hwang Jin-Seok Yang seung-Mok Yoo Chae-ho Lim Korea Institute of Industrial Technology

Pistons used in automobile engines are made of aluminum alloy; and endurance of high pressure and high temperature is required. Recently, high strength pistons are needed to cope with the increase of pressure and temperature in the engine cylinder. A high strength piston is possible when the piston casting has little or no casting defects, such as micro-pores and cracks. Generally the defects can be evaluated by non-destructive testing (NDT), and the most efficient ways for evaluation are using ultrasonics and computer tomography. In the present study, two NDT methods were compared and evaluated to investigate the defects in the aluminum piston castings. Artificial defects were machined by using very small drill bits with diameters 1, 0.5, 0.3, 0.2 and 0.1 mm. The defects were investigated by using an ultrasonic tester and a computer tomography system. Defects smaller than 0.3 mm may not be found by using the ultrasonic test, but the defects may be found by using the computer tomography system. The investigation conditions for detecting small defects and the scanning time for in-line defect analysis are discussed in the present study.

关键词： piston ultrasonic test computer tomography aluminum defect

Electrochemical biosensors for point-of-care testing

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Bio-Design and Manufacturing 2024年第4期7卷 548-565页

作者： Jinsol Kim Juho jeong seung Hwan Ko Department of Mechanical Engineering Seoul National UniversitySeoul 08826Republic of Korea Institute of Advanced Machinery and Design(SNU-IAMD) Seoul National UniversitySeoul 08826Republic of Korea

Point-of-care testing(POCT)is the practice of diagnosing and monitoring diseases where the patient is located,as opposed to traditional treatment conducted solely in a medical laboratory or other clinical *** has been less common in the recent past due to a lack of portable medical devices capable of facilitating effective medical ***,recent growth has occurred in this field due to advances in diagnostic technologies,device miniaturization,and progress in wearable *** these developments,electrochemical sensors have attracted interest in the POCT field due to their high sensitivity,compact size,and *** are used in various applications,from disease diagnosis to health status *** this paper we explore recent advancements in electrochemical sensors,the methods of fabricating them,and the various types of sensing mechanisms that can be ***,we delve into methods for immobilizing specific biorecognition elements,including enzymes,antibodies,and aptamers,onto electrode surfaces and how these sensors are used in real-world POCT settings.

关键词： Point-of-care testing(POCT) Electrochemical sensor Enzyme Antibody Health care

Progress in light-to-frequency conversion circuits based on low dimensional semiconductors

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Nano Research 2021年第9期14卷 2938-2964页

作者： seung Gi Seo seung Yeob Kim Jinheon jeong Sung Hun Jin Department of Electronic Engineering Incheon National UniversityAcademy-ro 119Yeongsu-guIncheon 22012Republic of Korea

As the scaling down of Si devices in the range less than few nm has been expedited up to a physical limit of Si,low dimensional materials have been regarded as one of next generation *** a variety of applications,studies on photodetectors have been actively investigated with their novel optical properties as well as astonishing electrical ***,most of research has focused on single device-type photodetector(i.e.,photo-diode or photo-transistor).Contrary to common photodetector,light-to-frequency circuits(LFCs)are based on frequency reading with photosensitive ring oscillators,which has better noise immunity and reduced system complexity,thus,can be utilized to novel application even in internet of things(loT)and bio&medical *** this review,low dimensional materials based circuit level photodetectors,which are core elements as the form of either inverters or ring oscillators for demonstration of LFCs,are *** with the introduction of low dimensional materials and their optical properties for optoelectronics,a fundamental concept for LFCs is specifically ***,research progress on low dimensional material based photosensitive inverters is addressed according to the types of ***,as one of practical method for the improvement of photodetector performance,molecular doping technology is ***,complete system of LFCs and its digitization for demonstration of production level,and potential application in the respective four aspects,(i)medical SpO_(2) detection,(ii)biological fluidic system,(iii)auto-lighting in agriculture,and(iv)optical feedback and sensing systems,are presented as systematic way to address the envisioned practical applications for the future displays including virtual reality and augmented reality,and *** a remark,LFCs based on low dimensional semiconductors are expected to be one of core components in trillion’s sensor area.

关键词： photodetector light-to-frequency conversion circuit transition metal dichalcogenide carbon nanotube

What is the most cost-effective strategy to screen for second primary colorectal cancers in male cancer survivors in Korea?

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World Journal of Gastroenterology 2009年第25期15卷 3153-3160页

作者： Sang Min Park Sun-Young Kim Craig C Earle seung-Yong jeong Young ho Yun National Cancer Center Goyang Department of Population and International Health Harvard School of Public Health Department of Family Medicine Seoul National University HospitalSeoul National University College of Medicine Program in Health Decision Science Department of Health Policy and ManagementHarvard School of Public Health Division of Population Sciences Department of Medical OncologyDana-Farber Cancer InstituteHarvard Medical School Department of Surgery Seoul National University HospitalSeoul National University College of Medicine Division of Cancer Control National Cancer Center

AIM： To identify a cost-effective strategy of second primary colorectal cancer （CRC） screening for cancer survivors in Korea using a decision-analytic model. METhoDS： A Markov model estimated the clinical and economic consequences of a simulated 50-year- old male cancer survivors＇ cohort, and we compared the results of eight screening strategies： no screening, fecal occult blood test （FOBT） annually, FOBT every 2 years, sigmoidoscopy every 5 years, double contrast barium enema every 5 years, and colonoscopy every 10 years （COL10）, every 5 years （COL5）, and every 3 years （COL3）. We included only direct medical costs, and our main outcome measures were discounted lifetime costs, life expectancy, and incremental cost- effectiveness ratio （ICER）. RESULTS： In the base-case analysis, the non-dominat- ed strategies in cancer survivors were COL5, and COL3. The ICER for COL3 in cancer survivors was $5593/life- year saved （LYS）, and did not exceed $10000/LYS in one-way sensitivity analyses. If the risk of CRC in can- cer survivors is at least two times higher than that in the general population, COL5 had an ICER of less than $10500/LYS among both good and poor prognosis of index cancer. If the age of cancer survivors starting CRC screening was decreased to 40 years, the ICER of COL5 was tess than $7400/LYS regardless of screening compliance. CONCLUSION： Our study suggests that more strict and frequent recommendations for colonoscopy such as COL5 and COL3 could be considered as economically reasonable second primary CRC screening strategies for Korean male cancer survivors.

关键词： Cost-effectiveness Second primary colorectal cancer Screening Cancer survivor

Photocatalytic decomposition of mobile-source related pollutants using a continuous-flow reactor

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Journal of Environmental Sciences 2010年第3期22卷 460-466页

作者： Wan-Kuen Jo seung-ho Shin Department of Environmental Engineering Kyungpook National University

This study evaluated the application of a continuous-flow photocatalytic reactor for the control of two mobile-derived pollutants, methyl-tertiary butyl ether （MTBE） and naphthalene, present at in-vehicle levels. Variables tested for this study included the hydraulic diameter （HD）, stream flow rate （SFR）, relative humidity （RH）, and feeding type （FT）. The fixed parameters included contaminant concentration, ultraviolet light source, and the weight of TiO2. In all experimental conditions the adsorption process reached equilibrium within 30 to 180 min for the target compounds, and the outlet concentrations of the photocatalytic oxidation （PCO） reactor while operating reached a steady state within 60 to 180 min. The degradation of the target compounds was dependent on RH, HD, FT, or SFR. The PCO system exhibited high degradation （up to nearly 100% for certain conditions） and mineralization efficiencies of target compounds, suggesting that this system can effiectively be employed to improve indoor air quality. Moreover, it was confirmed that trichloroethylene at urban-ambient level also could enhance the degradation efficiency of naphthalene when applying the PCO technology inside vehicles.

关键词： in-vehicle level methyl-tertiary butyl ether naphthalene trichloroethylene