• 청정기술
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• 제25권1호
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• pp.81-90
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• 2019

프로페인($C_3H_8$)의 건식 개질($CO_2$ 개질)을 통한 합성 가스($H_2$와 CO 혼합물) 제조를 위해 $Ni-CeO_2/{\gamma}-Al_2O_3$ 촉매가 충진된 유전체 장벽 방전 플라즈마 반응기를 사용하였다. 열 또는 플라즈마에 의해 환원된 $Ni-CeO_2/{\gamma}-Al_2O_3$ 촉매를 사용하여 $C_3H_8/CO_2$ 비율 1/3, 총 유량 $300mL\;min^{-1}$에서 플라즈마-촉매 건식 개질을 수행하였다. 건식 개질에 대한 촉매 활성은 온도범위 $500{\sim}600^{\circ}C$에서 평가되었다. $Ni-CeO_2/{\gamma}-Al_2O_3$ 촉매 제조를 위해 전구물질 수용액(질산니켈, 질산세륨)으로 함침된 ${\gamma}-Al_2O_3$를 공기 분위기에서 소성시킨 후, $H_2/Ar$ 분위기에서 환원시켰다. 촉매 특성 조사에는 X-선 회절분석기(XRD), 투과전자현미경(TEM), 전계 방출 주사전자현미경(FE-SEM), 승온 탈착($H_2-TPD$, $CO_2-TPD$) 및 라만 분광기가 이용되었다. 열로 환원된 촉매와 비교하면 플라즈마 방전하에서 환원된 $Ni-CeO_2/{\gamma}-Al_2O_3$ 촉매가 개질 반응을 통한 합성 가스 생산에서 보다 우수한 촉매 활성을 나타내었다. 또한, 플라즈마로 환원된 $Ni-CeO_2/{\gamma}-Al_2O_3$가 개질 반응의 문제점인 탄소퇴적 관점에서 장기 촉매 안정성을 보여주었다.

• 환경위생공학
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• 제22권2호
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• pp.9-20
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• 2007

The incineration process has commonly used for wastes amount reduction and thermal treatments of pollutants as the technologies accumulated. However, the process is getting negative public images owing to matter of hazardous pollutants emission. Specially dioxins became a main issue and were mostly emitted from municipal solid wastes incineration. In this reason, pyrolysis/gasification/melting process is presented as an alternative of incineration process. The pyrolysis/gasification/melting process, a novel technology, is middle of verification of commercial plant and development of technologies in Korea. But the survey about the pollutant emission from the process, and background data in these facilities is necessary. So in this survey, t is investigated that the behavior of chlorobenzenes and chlorophenols in plasma type pyrolysis/gasification/melting plant of pilot scale. We investigated discharging behavior of each phase of chlorobenzene through each process in the plsasma type pyrolysis/gasification/melting process. From this result, it was found that about 99 percent of particle-phase chlorobenzene was removed, but on the other hand gas-phase chlorobenzene was increased by about 600 percent through heat exchanger, flue gas cooling, system and semi dry absorption bag filter(SDA/BF). Also, this investigation presented that di-chlorobenzene(DCB) tri-chlorobenzene(TCB), tetra-chlorobenzene(TeCB), penta-chlorobenzene (PCB), except mono-chlorobenzene(MCB) and hexa-chlorobenzene(HCB) were increased through the flue gas cooling system and the semi dry absorption bag filter(SDA/BF). It was investigated that concentration of particle-phase chlorophenol was decreased by about 66 percent, but on the other hand, concentration of gas-phase chlorophenol was increased by about 170 percent through heat exchanger, flue gas cooling system, and semi dry absorption bag filter(SDA/BF). Also, it was found that di-chlorophenol(DCP), tri-chlorophenol(TCP), and penta-chlorophenol(PCP) were increased through the flue gas cooling system, and the semi dry absorption bag filter(SDA/BF). It can be considered that small-scale pilot facility and short investigation period might cause the concentration increase through the flue gas cooling system and the semi dry absorption bag filter(SDA/BF). A further study on real-scale pilot facility and accurate investigation may be required.

• Journal of Nutrition and Health
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• 제39권6호
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• pp.520-528
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• 2006

Free amino acids in epidermis function as a major component of Natural Moisturizing Factor (NMF), which maintains the optimal level of water in skin even at the low humidity. In fact, the depletion of free amino acids is reported in the epidermis of atopic dermatitis, the skin condition involving dryness. As an effort searching the dietary source for improving the level of water and free amino acid in epidermis, the dietary effects of silk protein, sericin (S) and fibroin (F) on trans epidermal water loss (TEWL), and plasma and epidermal levels of free amino acids were compared in this study. Thirty of male NC/Nga mice, an animal model of atopic dermatitis, were divided into three groups: group CA as an atopic control with control diet, group S: 1% sericin diet and group F: 1% fibroin diet. Ten of male BALB/c mice were served as group C (control group) with control diet. All mice were fed on diet and water ad libitum for 10weeks. Dry skin condition was established in group CA as TEWL was increased (148.7% of group C). In parallel, epidermal level of glutamate, one of major amino acids functioning as NMF, was dramatically decreased and epidermal levels of methionine and alanine were inversely elevated. Dietary supplementation of sericin (group S) reduced TEWL at the similar level with group C and increased epidermal levels of glutamate as well as serine and glycine, the other major amino acids as NMF. Despite a marked decrease of methionine and alanine, the reduction of TEWL and epidermal levels of glutamate, serine and glycine of group F were less than of group S. Furthermore, in contrast to similar levels of other free amino acids in plasma and epidermis of group S and group C, plasma and epidermal levels of other free amino acids, specifically phenylalanine, isoleucine, cysteine and tyrosine in epidermis of group F, were significantly higher than of group C. Together, our data demonstrate that dietary supplementation of sericin is more effective at improving dry skin condition that paralleled with the normalization of free amino acids in plasma and epidermis of NC/Nga mice.

• 동력기계공학회지
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• 제12권3호
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• pp.66-71
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• 2008

Diamond-like-carbon (DLC) coatings could be good candidates as solid lubricants for cutting tools in dry machining of aluminum alloy. In this work, DLC thin films were produced as a friction reduction coating for WC-Co insert tip using the plasma immersion ion beam deposition (PIIED) technique. DLC coatings were also coated on $Al_2O_3$ specimens and high temperature wear tested up to $400^{\circ}C$ in dry air to observe the survivability of the DLC coating in simulated severe cutting conditions using a pin-on-disc tribotester with Hertzian contact stress of 1.3GPa. It showed reduced friction coefficients of minimum 0.02 up to $400^{\circ}C$. And cutting performance of DLC coated WC-Co insert tips to Al 6061 alloy were conducted in a high speed machining center. The main problems of built-up edge formation in aluminum machining are drastically reduced with improved surface roughness. The improvements were mainly related to the low friction coefficient of DLC to Al alloy and the anti-adhesion of Al alloy to WE due to the inertness of DLC.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.375-378
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• 2002

We investigated the reduction of etching damage by additive O$_2$ in etching gas and recovery of etching damage by O$_2$ annealing. The PZT thin films were etched using additive Ar or O$_2$ into Cl$_2$/CF$_4$ gas mixing ratio of 8/2. In order to recover ferroelectric properties of PZT thin films after etching, the etched PZT thin films were annealed at 600 C in O$_2$ atmosphere for 10 min. The remanent polarization is decreased seriously and fatigue is accelerated in the PZT sample etched in Ar/(C1$_2$+CF$_4$) plasma, whereas these characteristics are improved in O$_2$/(Cl$_2$/CF$_4$). From x-ray photoelectron spectroscopy (XPS) analysis, the intensities of Pb-O, Zr-O and Ti-O peaks are changed and the etch byproducts such as metal chloride and metal fluoride are reduced by O$_2$ annealing. From electron probe micro analyzer (EPMA) and auger electron spectroscopy(AES), O$_2$ vacancy is observed after etching. In x-ray diffraction (XRD), the structure damage in the additive O$_2$ into C1$_2$/CF$_4$ is reduced and the improvement of ferroelectric behavioral annealed sample is consistent with the increase of the (100) and (200) PZT peaks.

• 해양환경안전학회지
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• 제17권2호
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• pp.155-160
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• 2011

현재 지구온난화 등의 환경문제로 인해 각종 산업분야에서 정량화에 대한 요구가 증대되어 해양산업에도 그 수요가 증가하고 있는 실정이다. 따라서 본 연구에서는 차세대 경량화 재료인 마그네슘이 활용되기 위해서 반드시 극복해야할 가장 중요한 특성인 내식특성에 대하여 고찰하고, 그 내식특성 향상을 위한 마그네슘 박막의 Morphology나 결정배향성의 영향을 해명하고자 하였다. 실험결과로부터 제작한 Mg 박막의 전기화학적 내식특성은 Ar 가스압이 높은 조건에서 제작한 막일수록 내식특성이 우수하였다. 이러한 경향은 표면 및 단면의 Morphology와 결정배향성과의 상관관계를 통하여 설명 가능하였다.

• Journal of Nutrition and Health
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• 제39권2호
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• pp.121-132
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• 2006

Minerals are extremely important in human metabolism, growth, and tissue repair. The risks of disturbances in mineral nutrition and metabolism are high following menopause. The aim of the study was to investigate the mineal nutrition status in middle-aged women (Pre & Postmenopausal) and the relation to climacteric symptoms. In the present study, we conducted the anthropometric measurement, climacteric symptoms survey and the dietary intakes including macronutrients, vitamins and minerals to assess the nutrient intakes. Also plasma mineral levels (Ca, P, Mg, Na, K, Fe, Cu, Zn) was measured. The participants were 105 middle-aged women (pre=51, Postmenopausal=54). The anthropometric measurement showed that 74% of subjects was overweight and obesity. The energy intakes were 83% of Korean EER. The macromineral intake (Ca, P, Mg, Na, K), Ca, P and Mg were 65%, > 116% and > 107% of Korean RI. Na and K intakes were > 243% and 53% of Korean AI. For the trace mineral intake (Fe, Cu, Zn), Fe, Cu and Zn intakes were 82%, > 146%, and 94% of Korean RI. The serum mineral concentration measurement, in case of Ca, Fe and Zn, > 10% of subjects showed lower level than normal clinical range. The most frequently appeared climacteric symptoms were dry eye, forgetfulness, difficult concentration, shoulder pain, fatique, depression & lonesomeness, backache, snore, dry skin, ankle & knee pain. In relation to mineral nutrition with climacteric symptoms, significant correlations have been founded between Ca intake and difficult concentration, Mg intake and snore, Fe & Zn intake and forgetfulness & dry skin, serum Ca concentration and forgetfulness, serum Na concentration and dry eyes & snore, serum K concentration and shoulder pain. From these results, it has been indicated that some mineral nutrition status may effect the prevention and reduction of climacteric symptoms in pre and postmenopause women.

• 자원리싸이클링
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• 제25권3호
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• pp.49-54
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• 2016

본 연구에서는, 아크 플라즈마 정련을 이용하여 지르콘샌드($ZrSiO_4$)를 지르코니아($ZrO_2$)와 실리카($SiO_2$)로 분리하였다. 실리카를 마이크로웨이브 침출을 통해 제거하고 고순도의 지르코니아를 얻었다. 플라즈마 퓨전은 두 가지 공정을 순차적으로 진행하였다. Ar 100% 분위기에서 환원 공정을 거친 후, Ar-$H_2$ 혼합 가스를 통해 정련과정을 거쳤다. 진공 챔버 내에서 냉각 후 지르코니아와 실리카로 이루어진 고상을 얻었다. 마이크로웨이브 침출을 위해 $240^{\circ}C$, 20% 황산용액을 사용하였다. 분석 결과 고순도(98.6%)의 지르코니아를 얻을 수 있었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 1999년도 추계학술발표회 초록집
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• pp.59-59
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• 1999

In this study, planer inductively coupled $Cl_2$ based plasmas were used to etch InGaN and the effects of plasma conditions on the InGaN etch properties have been characterized using quadrupole mass spectrometry(QMS) and optical emission spectroscopy(OES). As process conditions used to study the effects of plasma characteristics on the InGaN etch properties, $Cl_2$ was used as the main etch gas and $CHF_3,{\;}CH_4$, and Ar were used as additive gases. Operational pressure was varied from SmTorr to 3OmTorr, inductive power and bias voltage were varied from 400W to 800W and -50V to -250V, respectively while the substrate temperature was fixed at 50 centigrade. For the $Cl_2$ plasmas, selective etching of GaN to InGaN was obtained regardless of plasma conditions. The small addition of $CHF_3$ or Ar to $Cl_2$ and the decrease of pressure generally increased InGaN etch rates. The selective etching of InGaN to GaN could be obtained by the reduction of pressure to l5mTorr in $CI_2/IO%CHF_3{\;}or{\;}CI_2/IO%Ar$ plasma. The enhancement of InGaN etch rates was related to the ion bombardment for $CI_2/Ar$ plasmas and the formation of $CH_x$ radicals for $CI_2/CHF_3(CH_4)$ plasmas.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.555-557
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• 2004

We report the effect of the particle size (D50) and PSD (Particle Size Distribution) of glass frit on the transparency of transparent dielectric layer of PDP. The milling efficiency of wet milling with water was the best among the dry milling, wet milling with IPA and wet milling with water. The transparency increased with the reduction of particle size of glass frit as the milling time increased. Also the transparency changed by the PSD of glass frit. Glass frits of broad PSD showed high transparency compared with the glass frits of sharp PSD.