• Nuclear Engineering and Technology
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• 제56권3호
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• pp.1037-1051
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• 2024

This paper presents the construction results and design of the UNIST Reactor Innovation platform for small modular reactors as a versatile testbed for exploring innovative technologies. The platform uses simulant fluids to simulate the thermal-hydraulic behavior of a reference small modular reactor design, allowing for cost-effective design modifications. Scaling analysis results for single and two-phase natural circulation flows are outlined based on the three-level scaling methodology. The platform's capability to simulate natural circulation behavior was validated through performance calculations using the 1-D system thermal-hydraulic code-based calculation. The strategies for evaluating cutting-edge technologies, such as the integration of a solid oxide electrolysis cell for hydrogen production into a small modular reactor, are presented. To overcome experimental limitations, the hardware-in-the-loop technique is proposed as an alternative, enabling real-time simulation of physical phenomena that cannot be implemented within the experimental facility's hardware. Overall, the proposed versatile innovation platform is expected to provide valuable insights for advancing research in the field of small modular reactors and nuclear-based hydrogen production.

• Journal of Electrochemical Science and Technology
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• 제15권3호
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• pp.345-352
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• 2024

The synthesis of Pt nanoparticles and catalytically active materials using the electrochemical top-down approach involves dispersing Pt electrodes in an electrolyte solution containing alkali metal cations and support material powder using an alternating pulsed current. Platinum is dispersed to form particles with a predominant crystallographic orientation of Pt(100) and a particle size of approximately 7.6±1.0 nm. The dispersed platinum particles have an insignificant content of PtO_x phase (0.25±0.03 wt.%). The average formation rate was 9.7±0.5 mg cm^-2 h^-1. The nature of the support (carbon material, metal oxide, carbon-metal oxide hybrid) had almost no effect on the formation rate of the Pt nanoparticles as well as their crystallographic properties. Depending on the nature of the support material, Pt-containing catalytic materials obtained by the electrochemical top-down approach showed good functional performance in fuel cell technologies (Pt/C), catalytic oxidation of CO (Pt/Al₂O₃) and electrochemical oxidation of methanol (Pt/TiO₂-C) and ethanol (Pt/SnO₂-C).

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 2006년도 춘계학술대회
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• pp.57-58
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• 2006

Red ginseng is a classical traditional Chinese medicine. Among Chinese herbs, red ginseng has been considered as one of the tonics. Many studies indicated that red ginseng could enhance immune function of the human body. Red ginseng total saponin, ginsenoside, the most important active constituents identified in red ginseng can protect against myocardial ischaemia damage and protect endothelium against electrolysis-induced free radical injury. Macrophages play a significant role in host defense mechanisms. When activated, they inhibit the growth of a wide variety of tumor cells. The aim of this study was to determine the effects of pure ginsenoside Rb1 on immunostimulatory activity such as murine macrophage phagocytosis and proliferation of splenocytes. Furthermore, we investigated the effects of ginsenoside Rb1 on the production of nitric oxide (NO), reactive oxygen species (ROS) and proinflammatory cytokines (IL-1beta, IL-6, and TNF-alpha) in murine macrophage, RAW 264.7 cells. ROS have emerged as important signaling molecules in the regulation of various cellular processes. Ginsenoside Rb1 significantly increased production of ROS in dose dependent manner. As NO plays an important role in immune function, ginsenoside Rb1 treatment could modulate several aspects of host defense mechanisms due to stimulation. Treatment with ginsenoside Rb1 to macrophages induced the production of NO and proinflammatory cytokines and expression levels of these genes in a dose-dependent manner. Furthermore, incubation of RAW 264.7 cells with ginsenoside Rb1 showed a dose dependent increased phagocytosis activity and lymphocyte proliferation of splenocytes. Therefore, these results suggest that ginsenoside Rb1 has promising potential as a natural medicine for stimulation of the immune system.

• Korean Chemical Engineering Research
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• 제50권4호
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• pp.604-609
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• 2012

기능성화장품 소재로 사용하기 위한 후코이단의 특성 및 후코이단 분자량의 영향에 대해 연구하였다. 후코이단은 미역 포자엽에서 추출하였고 접촉글로우방전 전기분해(CGDE)방법에 의해 후코이단 분자량(35~160 kDa)을 조절하였다. 후코이단의 tyrosinase inhibition, 보습력, elastase 활성저해 효과와 항산화력(DPPH assay, radical scavenging)을 측정하여 화장품으로서 가능성을 확인하였다. 후코이단의 보습력은 최고의 보습제 중의 하나인 히아루론산의 보습력보다 높았고, 분자량이 감소함에 따라 보습력이 약간 증가하였다. 주름개선 효과실험인 elastase 활성저해 효과 실험결과 표준 비교물질인 adenosine 보다 높은 elastase 활성저해 효과를 보였다. 최고의 tyrosinase 저해효과, elastase 활성저해 효과, 항산화력(DPPH assay, radical scavenging)을 갖는 후코이단의 분자량은 100 kDa이었다.

• 청정기술
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• 제7권3호
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• pp.215-223
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• 2001

A present semiconductor cleaning technology is based upon RCA cleaning technology which consumes vast amounts of chemicals and ultra pure water(UPW) and is the high temperature process. Therefore, this technology gives rise to the many environmental issues, and some alternatives such as electrolyzed water(EW) are being studied. In this work, intentionally contaminated Si wafers were cleaned using the electrolyzed water. The electrolyzed water was generated by an electrolysis system which consists of three anode, cathode, and middle chambers. Oxidative water and reductive water were obtained in anode and cathode chambers, respectively. In case of NH4Cl electrolyte, the oxidation-reduction potential and pH for anode water(AW) and cathode water(CW) were measured to be +1050mV and 4.8, and -750mV and 10.0, respectively. AW and CW were deteriorated after electrolyzed, but maintained their characteristics for more than 40 minutes sufficiently enough for cleaning. Their deterioration was correlated with CO2 concentration changes dissolved from air. Contact angles of UPW, AW, and CW on DHF treated Si wafer surfaces were measured to be $65.9^{\circ}$, $66.5^{\circ}$ and $56.8^{\circ}$, respectively, which characterizes clearly the eletrolyzed water. To analyze the amount of metallic impurities on Si wafer surface, ICP-MS was introduced. It was known that AW was effective for Cu removal, while CW was more effective for Fe removal. To analyze the number of particles on Si wafer surfaces, Tencor 6220 were introduced. The particle distributions after various particle removal processes maintained the same pattern. In this work, RCA consumed about $9{\ell}$ chemicals, while EW did only $400m{\ell}$ HCl electrolyte or $600m{\ell}$ NH4Cl electrolyte. It was hence concluded that EW cleaning technology would be very effective for promoting environment, safety, and health(ESH) issues in the next generation semiconductor manufacturing.

• 한국응용과학기술학회지
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• 제32권2호
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• pp.188-193
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• 2015

고로슬래그는 유동성 장기강도 및 내구성이 좋고 수화열을 낮아 경화체를 제조함에 따른 적용성이 우수하지만, 몇 가지 문제점을 갖는다. 시공시간이 증가하고 회전속도가 늦고 초기강도가 낮다. 본 연구에서는 알칼리활성화를 이용한 경화체 제조에 있어 필요한 알칼리 수용액을 해수담수화 과정에서 발생하는 농축수의 전기분해를 통하여 공급하였으며. 알칼리 수용액을 이용하여 고로슬래그와 경화체를 제작하였다. 결과는 다음과 같이 요약할 수 있다 : 모르타르의 압축강도는 NaOH 2%이하일 때는 감소하고, 6% 이하까지는 증가한다. 그리고 NaOCl의 함량이 증가할수록 압축강도도 증가한다. 그러나 NaCl이 모르타르에 존재하면 초기강도보다 재령 28일차 강도는 감소하게 된다.

• 한국융합학회논문지
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• 제7권6호
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• pp.193-198
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• 2016

전기 도금한 도금 층의 집합조직은 전해조건에 의해 변화하는 것으로 알려져 있다. 도금층의 집합조직은 도금층의 미세조직과 표면 형상과 관계가 있으며 도금층의 기계적인 성질에 영향을 미친다. 그러므로 도금층의 집합조직의 변화양상의 이해는 매우 중요하다. 또한 전기도금 층은 열처리 됐을 때 재결정이 일어난다. 그 재결정 집합조직은 도금 층의 초기 성장 집합조직과 다르게 된다. 전기 도금한 도금 층의 그 미세조직, 표면 형상, 집합조직과 기계적인 성질은 용액조성, 과전압, pH, 전류밀도와 용액온도 등의 전해조건에 의해 변화한다. (111)과 (110)집합조직을 갖는 구리도금 층을 융합연구를 통해 황산 욕으로부터 얻을 수 있었다. 이 연구에서는 (110) 또는 (111)집합조직을 갖는 구리도금 층을 황산 욕에서 얻고, 그 (110) 또는 (111)집합조직으로의 변화와 기계적 성질을 설명할 수 있는 모델을 제시하였다.

• 한국수소및신에너지학회논문집
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• 제26권6호
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• pp.524-531
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• 2015

To improve the electrochemical and mechanical characteristics, engineering plastic of the sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK). The SPEEK organic-inorganic blended composite membranes were prepared by sol-gel casting method. It was loaded with the highly dispersed ceria and cesium-substituted molybdosilicic acid (Cs-MoSiA) and 1,4-diiodobutane which was cross-linking agent contents of $10{\mu}L$. Cs-MoSiA was added to increase proton conductivity. Ceria ($CeO_2$) was used as a free radical scavenger which degrade the membrane in polymer electrolyte membrane water elctrolysis (PEMWE). In conclusion, CL-SPEEK/Cs-MoSiA/Ceria 1% composite membrane showed high proton conductivity 0.2104 S/cm at $25^{\circ}C$ which was better than Nafion 117 membrane.

• 한국환경과학회지
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• 제24권12호
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• pp.1629-1637
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• 2015

To develop various usable water from coal seam gas (CSG) water that needs to be pumped out from coal seams for methane gas production, a feasibility study was carried out, evaluating and analysing a recent report (Coal Seam Gas Water Management Policy 2012) from Queensland State Government in Australia to suggest potential CSG water treatment options for fit-for-purpose usable water production. As CSG water contains intrinsically high salinity-driven total dissolved solid (TDS), bicarbonate, aliphatic carbon, $Ca^{+2}$, $Mg^{+2}$ and so on, it was found that appropriate treatment technologies are required to reduce the hardness below 60 mg/L as $CaCO_3$ by setting the reduction rates of $Ca^{+2}$, $Mg^{+2}$ and Na+ concentrations, as well as TDS reduction. Also, Along with fiber filtration and membrane separation, an oxidation degradation process was found to be required. Along with salinity reduction, as CSG water contains organic compounds (TOC: 248 mg/L, $C_6-C_9$: <20 mg/L and $C_{10}-C_{36}$: <60 mg/L), compounds with relatively high molecular weights ($C_{10}-C_{36}$) need to be treated first. Therefore, this study suggests a combined system design with filtration (Reverse osmosis) and oxidation reduction (electrolysis) technologies, offering proper operating conditions to produce fit-for-purpose usable water from CSG water.

• 한국지하수토양환경학회지:지하수토양환경
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• 제8권3호
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• pp.56-60
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• 2003

전기분해에 의한 부상현상을 이용하여 유류로 오염된 토양 세정 후 발생되는 유출수 중 유분 등을 분리하기 위한 적정 운전조건을 찾고자 하였다. 전기분해 반응조(200${\times}$10${\times}$15cm)를 이용하여 혼합계면활성제($POE_5$ : $POE_{14} $, 1:1) 1%용액에 디젤을 1,000 mg/L 농도로 용해시켜 실험하였다. 양극에는 티타늄 코팅전극, 음극으로는 스테인레스 스틸전극을 이용하였다. 반응시간은 62분(반응 :60분, 부상시간 :2분)이었으며 전압은 6V였다. 전해질 첨가에 의한 영향을 알아보기 위하여 실험한 결과, 전해질을 첨가하였을 경우 첨가하지 않았을 때보다 40% 정도의 효율이 증가하였다. 적정 전해질, 주입농도 및 반응시간을 알아보기 위하여 1N NaCl과 NaOH의 농도를 변화시켜 가면서 실험하였다. NaCl의 경우 더 좋은 효율을 나타내었다. 전해질의 농도는 0.2-1.0%의 농도범위에서 NaCl와 NaOH 모두 농도에 따라 순차적으로 효율이 증가하였다. 두 전해질 모두 0.4-1.0% 농도 범위에서 평형에 도달하는 시간은 20분으로 나타났다.