탄소층으로 캡슐화된 Ni나노입자 촉매의 CO₂ 메탄화 반응

김혜정,김승보,김동현,윤재랑,김민재,전상구,이경자,이규복,Kim, Hye Jeong,Kim, Seung Bo,Kim, Dong Hyun,Youn, Jae-Rang,Kim, Min-Jae,Jeon, Sang Goo,Lee, Gyoung-Ja,Lee, Kyubock 한국재료학회 2021 한국재료학회지 Vol.31 No.9

Carbon-encapsulated Ni catalysts are synthesized by an electrical explosion of wires (EEW) method and applied for CO₂ methanation. We find that the presence of carbon shell on Ni nanoparticles as catalyst can positively affect CO₂ methanation reaction. Ni@5C that is produced under 5 % CH₄ partial pressure in Ar gas has highest conversions of 68 % at 350 ℃ and 70 % at 400 ℃, which are 73 and 75 % of the thermodynamic equilibrium conversion, respectively. The catalyst of Ni@10C with thicker carbon layer shows much reduced activity. The EEW-produced Ni catalysts with low specific surface area outperform Ni catalysts with high surface area synthesized by solution-based precipitation methods. Our finding in this study shows the possibility of utilizing carbon-encapsulated metal catalysts for heterogeneous catalysis reaction including CO₂ methanation. Furthermore, EEW, which is a highly promising method for massive production of metal nanoparticles, can be applied for various catalysis system, requiring scaled-up synthesis of catalysts.

DOE를 적용한 카메라폰 모듈용 비구면 Glass 렌즈의 가압성형조건 연구

김혜정,차두환,이준기,김상석,김정호,Kim, Hye-Jeong,Cha, Du-Hwan,Lee, Jun-Key,Kim, Sang-Suk,Kim, Jeong-Ho 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.8

This study investigated the pressing conditions in the molding of aspheric glass lenses for the mega pixel phone camera module using the DOE method. Tungsten carbide (WC; Japan, Everloy Co., 002K),which contained 0.5 w% cobalt (Co), was used to build the mold. The mold surface was ultra-precision ground and polished, and its form accuracy (PV) was 0.85um in aspheric surface. We selected four factors, pressing temperature, force and time of first step, and force of second step, respectively, as the parameters of the pressing process. in order to reduce the number of experiments, we applied fractional factorial design considering the main effects and two-way interactions. The analysis results indicate that the only two main effects, the pressing temperature and the time of pressing step 1, are available for the form accuracy (PV) of the molded lens. The analysis results indicated that the best combination of the factors for lowering the form accuracy(PV) value of molded lens was to have them at their low levels.

시뮬레이션을 활용한 폰카메라 렌즈모듈 부품용 사출금형개발

김혜정,김재훈,김영규,송준엽,문덕희,Kim, Hye Jeong,Kim, Jae Hoon,Kim, Yeong Gyoo,Song, Jun Yeob,Moon, Dug Hee 한국시뮬레이션학회 2013 한국시뮬레이션학회 논문지 Vol.22 No.4

휴대폰 시장의 확산으로 인하여 휴대폰에 장착되는 카메라 렌즈모듈의 수요도 급증하고 있다. 렌즈모듈 부품의 경우 해상도의 증가에 따른 사출공정의 품질보증과 원가절감이라는 두 가지 목표를 달성해야 한다. 따라서 본 논문에서는 더블카세트 방식의 금형구조를 이용하여 경통과 쉴드 두 종류의 제품을 개발하기 위해 시뮬레이션을 활용한 사례를 소개한다. 개발과정에서 두 종류의 시뮬레이션 기술을 활용하였는데, 첫 번째는 금형 설계단계에서 사출품의 성형성을 분석하기 위한 시뮬레이션(일명 Computer Aided Engineering)을 Mold Flow$^{TM}$를 사용하여 수행하였고, 두 번째는 사출기에 금형을 장착한 후 제품이 사출되어 취출하는 동작을 분석하기 위한 동작 시뮬레이션을 DPM Assembly$^{TM}$를 이용하여 수행하였다. 개발 결과 기존 방식에 비해 제품의 생산성이 300% 이상 증가하는 효과를 얻었다. The demand of a camera-lens-module which is installed in mobile phone has been increased explosively as the increase of mobile phone market. Recently, two missions are given to the parts manufacturer of lens module, and they are how to keep the quality of injection moulding process as the increase of resolution, and how to decrease manufacturing cost. In this paper, a simulation study is introduced which is used for developing barrel and shield considering the double-cassette type of mould. At first, the simulation for injection process using Mold Flow$^{TM}$ is applied in the phase of mould design, and mechanical simulation using DPM Assembly$^{TM}$ is applied for collision detection between picking robot and mould. As a result, the productivity increased more than 300%.

굴삭기 부품 용접 자동화라인의 셀생산방식 적용을 위한 시뮬레이션 연구

김혜정,이승우,문덕희,Kim, Hye Jeong,Lee, Seung Woo,Moon, Dug Hee 한국시뮬레이션학회 2013 한국시뮬레이션학회 논문지 Vol.22 No.2

다품종 소량생산이 보편화 되면서 하나의 생산라인에서 여러 종류의 제품을 교대로 생산하는 혼류생산방식이 보편화 되었다. 하지만 흐름라인 방식의 혼류생산에서는 필연적으로 작업장 간의 공정시간 불균형이 존재한다. 따라서 이러한 공정불균형에 의한 대기의 낭비를 최소화하기 위하여 기존의 흐름생산방식에서 셀생산방식으로 전환하는 시도가 빈번하게 발생한다. 본 논문에서는 굴삭기 부품을 생산하는 혼류흐름라인 방식의 자동화 로봇 용접라인을 FMC 개념의 직선형 셀방식으로 전환하는 과정에서 타당성 검토를 위해 시뮬레이션을 수행한 사례연구 결과를 소개한다. 분석결과 26.7%의 생산량 증가와 55% 이상의 리드타임 감소효과가 예상되었다. 또한 향후 제품 생산비율의 변화에 따른 민감도분석을 수행하였다. Mixed model production system means that various products are manufactured alternately in a line, and it has become a popular system in the era of multi-product small-quantity production. However, in the mixed model production system using flow line, the unbalance among stations is not inevitable because the workloads of stations cannot be the same. Thus, flow line system has been replaced to cellular manufacturing system for reducing the loss of waiting due to the unbalance of stations. In this paper, we introduce the simulation case study of an automated welding line which produces the parts of excavator. The factory has considered replacing the mixed model flow line to the cellular manufacturing system based on FMC concept. The increase of production quantity is estimated about 26.7%, and the lead time is reduced more than 55%. Furthermore sensitivity analyses are conducted considering the changes of product-mix.

양택 풍수지리의 방위관 - "택경(宅經)"을 중심을 -

김혜정,Kim, Hye-Jung 한국건축역사학회 2009 건축역사연구 Vol.18 No.2

This research was to analyze the direction ideas of residential Feng Shui. In ancient China residential places were been established by Xiangzhai(相宅) and Buzhai(卜宅) usages. And ancient Chinese always considered geographical features of mountains and waters for setting up their living places. Geographical features were also considered importantly ih representative residential Feng Shui books, Zhaijing(宅經) and Yangzhaisanyao(陽宅三要). In Zhaihing, 24 direction ideas are co-related with Fagui(八卦) and GanZhi(千支) theories, and they are most important residential Feng Shiui direction theories. The basic thoughts of 24 direction ideas of Zhaijing were already formed in Qin(秦) dynasty and modified in early Han(漢) dynasty. In Zhaijing, residential places were splited into Yangzhai(陽宅) and Yinzhai(陰宅) according to YinYang's Qi directions. Those were actually formed from meticulous observations on changing processes of YinYangWuXing(陰陽五行)'s Qi(氣). Constantly changed Qi of YinYangWuXing were studied by old chinese people from the observations on the sun, the moon, the five stars, the Great Bear, and ErShiBaXiu(二十八宿). The origin of Zhaijing's direction ideas is the direction system of ShiPan(式盤) in Qin and Han dynasty. On ShiPan TianGan(天干) Dizi(地支) Fagui TianDiRenGui(天地人鬼) were arranged very systematically into four and 24 directions. DongxiSizhai(東西四宅) theories of Yangzhaisanyao had edited more lately than Zhaijing(宅經), and formed according to Fagui(八卦)'s YinYang(陰陽) principles. But the basic ideas is same with Zhaihing's. It proves that residential Feng Shui theories were constantly improved and modified. And both residential Feng Shui direction ideas of Zhaijing and Yangzhaisanyao are the gentral ideas in old china. The point of that ideas is Sky's four or 24 directions are correspndence with the earth's. It came from the traditional thoughts that Heaven, Earth, and mankind are c0-related and influenced each other according to Qi's changing processes. Gather up above mentioned, the direction ideas of residential Feng Shui is a systematic thoughts of old chinese for harmonizing Tian-Di-Ren-Gui, and is their specific methods for harmonizing the nature's Qi, mankind and spirits.

Evaluation of time-dependent antimicrobial effect of sodium dichloroisocyanurate (NaDCC) on Enterococcus faecalis in the root canal

김혜정,박세희,조경모,김진우,Kim, Hye-Jeong,Park, Se-Hee,Cho, Kyung-Mo,Kim, Jin-Woo The Korean Academy of Conservative Dentistry 2007 Restorative Dentistry & Endodontics Vol.32 No.2

이염화이소시아뉼산나트륨 (NaDCC)은 염소 화합물의 일종으로 차아염소산나트륨 (NaOCl)과 비교 시 동일한 농도의 용액에서 같은 염소 이온을 가지고 있으며 비슷한 정도의 항균력을 가진다고 알려져 있다 이 연구의 목적은 이염화이소시아뉼산나트륨 근관 내 사용 시 시간에 따른 항균성을 평가하고 이를 현재 근관세척제로 사용되고 있는 차아염소산나트륨 및 클로르헥시딘 (CHX)과 비교하고자 하였다. E. faecalis에 대한 세 가지 제재의 최소증식억제 농도 (MIC)를 실험한 결과 NaOCl과 NaDCC에서는 0.125%를 보였고 CHX에서는 0.063%로 나타났다. 근관 내 사용에 대한 실험은 최근에 발거된 128개의 단근치를 사용하였으며 치경부와 치근단 부위를 절단하여 10 mm 길이를 가지는 시편을 만들었다. 시편의 내경은 #3 Gates-Glidden drill을 이용하여 동일하게 하였다. 각각의 치아 시편의 근관 내에 E. faecalis를 접종하고 3일간 배양한 후 40개씩 3개의 군으로 분류하고 대조군으로 8개의 시편을 이용하였다. 실험군 1, 2, 3은 각각 NaDCC, NaOCl, CHX으로 근관세척하였고 대조군은 멸균된 식염수를 이용하였다. 각 군은 다시 12시간, 24시간, 72시간, 7일의 시간에 따라 4개의 하위 군으로 분류하였다. 정해진 시간이 지난 후 멸균된 paper point를 이용하여 근관 내용물을 채취하고 BHI agar plate로 옮겨 배양하였다. 그 후 #4, 5GG drill을 이용하여 근관 내면을 삭제하고 이 때 생겨나는 상아질을 멸균된 증류수가 들어있는 시험관에 넣었다. 이것을 희석하여 BHI agar plate로 옮겨 배양하였다. 24시간이 지난 후 bacterial CFU를 측정하였다. 실험 결과 모든 실험군에서 bacterial CFU가 관찰되지 않았고 E. faecalis에 대한 세 가지 제재 모두 비슷한 항균 효과를 보였다. 멸균된 식염수를 이용한 대조군에서는 모두 bacterial CFU가 존재하였다. NaDCC를 근관세척제로 사용할 경우 1주 이내의 시간 동안에는 적절한 항균효과를 유지 할 수 있을 것이라 생각되며 임상에 적용하기 위해서는 조직 용해도를 비롯한 치근단 조직에 대한 직접적인 영향 등의 평가가 더 이루어져야 할 것으로 생각된다. The purpose of this study was to assess the antibacterial effect of sodium dichloroisocyanurate (NaDCC), sodium hypochlorite (NaOCl), and chlorhexidine (CHX) on Enterococcus faecalis and to evaluate and to compare the time-dependant antimicrobial effect of NaDCC with NaOCl and CHX in the root canal in vitro before and after instrumentation. Extracted Human single teeth were prepared by serial instrumentation technique. The samples were autoclaved and contaminated for 3 days with E. faecalis monocultures. The teeth were then divided into 4 groups Each group was irrigated and inserted with 2% NaOCl, 2% NaDCC, 2% CHX and steri)ized saline. After 6, 12, 24, 72h, and 1 week incubation, sterilized paper point was inserted into the root canal. Paper points containing root canal contents were then placed on the agar plate. And then each root cana) was prepared with #4 and #5 GG (Gates-Glidden) drill. The debris were collected in the sterilized microtube and the plates were incubated at $37^{\circ}C$ in an increased $CO_2$ atmosphere. After 24h incubation the growth of bacteria around the paper points were measured. NaOCl and NaDCC solution shows similar antimicrobial effect for E. faecalis at 6, 12, 24, 72h and 1 week. In centrol group, irrigated with sterilized saline, no antimicrobial effect was observed. The results are in agreement with other investigators, who have shown the bactericidal property and possibility of NaDCC as a root canal irrigation solution. Thus it seems that NaDCC solutions can be clinically applied into the root canal within 1 week after dilution.

나눔으로 고객과 하나되는 KIHA - 취약계층의 건강을 책임지는 창원산업보건센터

김혜정,Kim, Hye-Jeong 대한산업보건협회 2019 산업보건 Vol.372 No.-

耳鳴에 關한 文獻的 考察

김혜정,김중호,채병윤,Kim, Hye-Jeong,Kim, Jung-Ho,Chae, Byeong-Yun 대한한방안이비인후피부과학회 1990 한방안이비인후피부과학회지 Vol.3 No.1

언택트 시대 줌 기반 영어 수업에서 학습 앱 활용의 효율성

김혜정,Kim, Hye-Jeong 한국융합학회 2021 한국융합학회논문지 Vol.12 No.4

본 논문의 목적은 줌을 기반으로 학습용 앱 활용이 학습자들의 영어 성취도에 미치는 영향을 살펴보고 이를 통해 줌 기반의 학습용 앱을 활용한 영어 수업의 효율성을 고찰하고자 한다. 본 연구는 줌 기반 수업에서 English Central 앱을 활용하였으며 이를 통해 다양하면서도 학습자들의 참여를 유도하는 영어 활동을 수행하였다. 줌 기반의 EC 앱 활용 수업의 효율성을 파악하기 위해 1차와 2차 성취도 테스트, 개방형 설문조사를 실시하였다. 두 차례의 테스트 결과 줌 기반의 EC 앱 활용 수업은 학습자들의 영어 성취도에 긍정적인 영향을 미치는 것으로 나타났다. 설문 조사결과 학습자들은 줌 기반 수업과 EC 앱 활용에 대해 만족도가 높은 것으로 나타났다. 줌 기반 수업에 대한 만족의 이유는 "부족한 수업 내용 보완", "영어 연습", "실시간 소통과 의견 공유" 으로 나타났다. 학습용 앱 활용에 대해 만족하는 이유는 "지루하지 않음", "영어의 4기술 훈련", "즉각적인 피드백"으로 나타났다. 변화된 언택트 시대 교수자들은 변화된 환경에 맞는 변화된 수업 도구의 효율적 사용을 위해 노력해야 한다. This study examined how the use of learning apps in Zoom-based classes affects learners' English achievement and assessed the efficiency of app use in Zoom-based English classes. The study utilized the English Central (EC) app to induce learners to actively participate in zoom-based classes. To assess the app's efficiency, two rounds of achievement tests and an open-ended questionnaire were administered. The two tests showed that Zoom-based EC app utilization classes positively affected learners' English achievement and the questionnaire revealed that the learners were highly satisfied with using the EC app in Zoom-based classes. The participants praised this approach for "complementing insufficient class content" and facilitating "immediate feedback" (on the EC app), "English practice," and "real-time communication and sharing of opinions" (on Zoom-based classes), describing it as "not boring" and "4 skill training in English." Instructors should strive to efficiently use such new teaching tools in the evolving environment of the untact era.

MicroRNA-148a/b-3p regulates angiogenesis by targeting neuropilin-1 in endothelial cells

김혜정,고영림,박효진,Haiying Zhang,Yoonjeong Jeong,Yeomyeong Kim,노민영,Songyi Park,Young-Myeong KIm,권영근 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

MicroRNAs (miRs) are crucial regulators of vascular endothelial cell (EC) functions, including migration, proliferation, and survival. However, the role of most miRs in ECs remains unknown. Using RNA sequencing analysis, we found that miR-148a/b-3p expression was significantly downregulated during the differentiation of umbilical cord blood mononuclear cells into outgrowing ECs and that decreased miR-148a/b-3p levels were closely related to EC behavior. Overexpression of miR-148a/b-3p in ECs significantly reduced migration, filamentous actin remodeling, and angiogenic sprouting. Intriguingly, the effects of decreased miR-148a/b-3p levels were augmented by treatment with vascular endothelial growth factor (VEGF). Importantly, we found that miR-148a/b-3p directly regulated neuropilin-1 (NRP1) expression by binding to its 3′-untranslated region. In addition, because NRP1 is the coreceptor for VEGF receptor 2 (VEGFR2), overexpression of miR-148a/b-3p inhibited VEGF-induced activation of VEGFR2 and inhibited its downstream pathways, as indicated by changes to phosphorylated focal adhesion kinase (FAK), extracellular signalregulated kinase (ERK), and p38 mitogen-activated protein kinase. Collectively, our results demonstrate that miR-148a/ b-3p is a direct transcriptional regulator of NRP1 that mediates antiangiogenic pathways. These data suggest that miR148a/b-3p is a therapeutic candidate for overcoming EC dysfunction and angiogenic disorders, including ischemia, retinopathy, and tumor vascularization.