Sol-Precipitation법으로 제조된 WO₃ 나노분말을 이용한 후막 센서의 NO₂ 감지 특성

류현욱,박경희,김인천,홍광준,박진성,Ryu, Hyun-Wook,Park, Kyung-Hee,Kim, In-Chun,Hong, Kwang-Joon,Park, Jin-Seong 한국재료학회 2002 한국재료학회지 Vol.12 No.12

Nanosized $WO_3$ powders were synthesized by the sol-precipitation process using $WCl_{6}$ as the starting material, ethanol as a solvent and $NH_4$OH solution as a precipitant, followed by a washing-drying treatment and calcination. The effects on the powder crystallinity and microstructure of calcination temperature were investigated with XRD and FE-SEM. The $WO_3$ powders calcined at $500^{\circ}C$ and $700^{\circ}C$ showed good crystallinity and their mean particle size was 30nm and 70nm, respectively. These powders were used for the preparation of pastes which were printed as thick films on alumina substrates with comb-type Pt electrodes. The particle size strongly influenced the $NO_2$ gas sensing property of the thick films. A significant reduction in the $NO_2$ sensitivity was observed for the film prepared from larger particle size, having thus a larger grain size. For the film having a smaller grain size, on the other hand, the higher $NO_2$ sensitivity was observed and the sensitivity increased with $NO_2$ concentration.

도포-열분해법을 이용한 비대칭 세라믹 분리막 제조

류현욱,김병훈,Ryu, Hyun-Wook,Kim, Byung-Hoon 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.12

입도가 다른 두 가지 고순도 ${\alpha}-Al_2O_3$ 분말을 이용하여 slip casting법과 담금코팅(dip coating)법으로 다공질 알루미나 지지체와 중간층을 각각 제조하였으며, 그 위에 분리막인 산화티탄($Tio_2$)층을 Ti-naphthenate용액으로 screen printing한 후 열분해시켜 형성시킴으로써, 3층 구조의 비대칭성 세라믹 분리막을 제조하였다. 알루미나 지지체의 곡강도, 기공율 및 평균 기공크기는 각각 231 Kg/$cm^2$, 30.26%, 0.19 ${mu}m$였으며, 중간층은 두께가 약 30 ${mu}m$, 평균 기공크기가 0.063 ${mu}m$였다. 또한 최상층 $Tio_2$ 분리막은 그 두께가 약 0.5 ${mu}m$였으며 평균 약 20 nm 정도의 미세 기공들이 매우 균일하게 형성되어 있었다. The fabrication of a three-layered asymmetric ceramic membrane was performed by slip casting of the porous alumina support and dip coating of the alumina intermediate layer using high purity ${\alpha}-Al_2O_3$ powders that have different particle size, followed by screen printing-pyrolysis of the $Tio_2$ layer as an ultrafilteration membrane using Ti-naphthenate solution. The bending strength, porosity and mean pore size of the alumina support were 231 kg/$cm^2$s, 30.26% and 0.19 ${mu}m$, respectively. The thickness of the intermediate layer was 30 ${mu}m$ and the mean pore size of that was 0.063 ${mu}m$. Also, the top layer was 0.5 ${mu}m$ thick and micropores with about 20 nm size were formed uniformly.

플라즈마 가스와 RF 파워에 따른 NiO 박막의 우선배향성 및 표면형상 변화

류현욱,최광표,노효섭,박용주,권용,박진성,Ryu Hyun-Wook,Choi Gwang-Ryo,Noh Whyo-Sup,Park Yong-Ju,Kwon Yong,Park Jin-Seong 한국재료학회 2004 한국재료학회지 Vol.14 No.2

Nickel oxide (NiO) thin films were deposited on Si(100) substrates at room temperature by RF magnetron sputtering from a NiO target. The effects of plasma gas and RF power on the crystallographic orientation and surface morphology of the NiO films were investigated. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were employed to characterize the deposited film. It was found that the type of plasma gases affected the crystallographic orientation, deposition rate, surface morphology, and crystallinity of NiO films. Highly crystalline NiO films with (100) orientation were obtained when it was deposited under Ar atmosphere. On the other hand, (l11)-oriented NiO films with poor crystallinity were deposited in $O_2$. Also, the increase in RF power resulted in not only higher deposition rate, larger grain size, and rougher surface but also higher crystallinity of NiO films.

하악골 결손부의 치조골 신장술을 이용한 임플란트 식립 증례보고

류현욱,Ryu, Hyun-Wook 대한악안면성형재건외과학회 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.4

Objective : This is to report the effectiveness of intraoral distraction osteogenesis, iliac bone graft for alveolar augmentation in the extremely atrophied alveolar defects after infected allobone grafted area. Subjects and Methods : Anterior segmental osteotomy was performed and the trans-oral alveolar distractors (Martin, Germany) were applied in patient with the severe acquired anterior mandibular and mandibular defect after ameloblastoma enucleation. Iliac bone grafts were performed in defect sites and distraction osteogenesis were treated. After latent period for 1 week, the osteomized alveolar segments were distracted by 0.75 mm a day (0.25 mm/1 turn) for 10 days The consolidation period was about 12 weeks. Thereafter, 2 titanium threaded implants were simultaneously installed with removal of distractor. For oral rehabilitiation, The implants were installed in maxilla, mandible. It was tested with clinically and radiographically. Results : Amounts of acquired alveolar bone were 10 mm with the increased width of the ridge crests and soft tissue expansion. Dental implants installated on the augmented alveolar ridges in 12 weeks after distraction were confirmed as in good osseointegration and in good function without any complications. Conclusion : Intraoral distraction osteogenesis can be a good option for alveolar ridge augmentation of the severely atrophied ridges and soft-tissue defects.

조절형 인공수정체에서 전방깊이의 측정을 통한 조절력의 평가

류현욱,정성근.Hyun Wook Ryu. M.D.. Sung Kun Chung. M.D. 대한안과학회 2006 대한안과학회지 Vol.47 No.5

Purpose: To investigate the accommodating potency of the 1CU accommodative posterior chamber intraocular lens (PC IOL), according to pilocarpine-induced ciliary muscle contraction, near visual acuity, and distance-corrected near visual acuity after implantation of the IOL. Methods: In a prospective study, 9 eyes of 7 patients (mean age 48±14.9 years [range 23 to 71 years]) had phacoemulsification and PC IOL (1CU?, Humanoptics). Distance refraction, distance visual acuity (VA), distance-corrected VA (DCVA), near visual acuity (NVA), and distance-corrected near visual acuity (DCNVA) were determined at 2 week, 1, 2, 6, and 12 months after surgery. Anterior chamber depth (ACD) was measured 3 times with the Orbscan? (Orbtek, U.S.A.), and averaged. Then ACD was repeatedly measured within 90 minutes after administration of pilocarpine 2% eyedrops 3 times at 10 minutes interval. Results: At 2 weeks, 1, 2, 6 and 12 months after surgery, the mean DCNVA was 0.55±0.23, 0.37±0.14, 0.40±0.22, 0.51±0.20, and 0.56±0.20, respectively. The mean ACD decrease (mm) was 0.57±0.77, 0.91±0.69, 0.17±0.45, 0.35±0.40 and 0.59±0.31, respectively, using Orbscan? after pilocarpine 2% eyedrops. There was statistically significant correlation between the pilocarpine-induced IOL movement and DCNVA (r=0.439, P=0.012). Conclusions: 1CU accommodative PC IOL provided relatively good DCNVA and accommodating potency for up to 1 year. It is necessary to investigate accommodative change for a longer time period.

적색 양파에서 안토시아닌 함량 조절 양적형질유전자좌와 연관된 SNP 분자표지 개발

류현욱(Hyunwook Ryu),김성길(Sunggil Kim),이혜은(Hye-Eun Lee),한지원(JiWon Han),이준대(Jundae Lee) 한국육종학회 2021 한국육종학회지 Vol.53 No.2

The bulb onion (Allium cepa L.), one of the most important vegetables worldwide, contains various functional compounds suchas quercetin, allicin, and flavonoids. Red onions are rich in anthocyanins, a flavonoid that is a functional phytochemical with antioxidativeand anticancer activities. In the previous study, two quantitative trait loci (QTLs) (qAC4.1 and qAC4.2) controlling the anthocyanin contentwere identified on chromosome 4 in an F2 population derived from a cross between A. cepa ‘SP3B’ and ‘H6’. In this study, we developedsingle nucleotide polymorphism-based high-resolution melting (HRM) markers linked to QTLs qAC4.1 and qAC4.2. In addition, we constructeda new genetic linkage map of chromosome 4 using HRM markers and performed a QTL analysis. The QTL qAC4.1 was false, while qAC4.2was a major QTL. The QTL peak position, logarithm of the odds value, and phenotypic variance explained of qAC4.2 was 53.6 cM, 7.45, and 22.51%,respectively. Four HRM markers (AC4.2_65336.1_1123-HRM, AC4.2_53230.3_454-HRM, AC4.2_11999.1_756-HRM, and AC4.2_14596.1_345-HRM)within the QTL region of qAC4.2 were developed in this study. The average anthocyanin content of B (homozygous paternal) genotypes washigher than that of A (homozygous maternal) and H (heterozygous) genotypes for all markers. Consequently, these markers will be useful formarker-assisted selection to develop onion cultivars with high anthocyanin content.

실물자산시장에서의 정보효과에 관한 연구

류현욱(Ryu, HyunWook) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.11

본 연구는 금융투자시장에서 적극적으로 연구되는 정보효과에 대한 동태적 분석을 시도하였다. 기존문헌(들)을 통해 정보거래가 갖는 효과에 대해 고찰하였으며, 국내 아파트시장을 대상으로 실증분석하였다. 자료는 국토해양부에서 공개하는 실거래 자료가 사용되었으며, 2006년부터 2015년까지의 월별 아파트 Data를 EGARCH 분석모형에 적용하였다. 추정한 결과, 전기 거래량이 주택가격의 변동성에 영향을 미치고 있는 것으로 확인한 바, 주택거래량이 전달하는 정보효과(information role)가 금융투자시장과 유사하게 나타날 수 있음을 확인하였다. This study examines the dynamic relations between housing price and trading volume in a set of apartment markets in Republic of Korea to explore the informational role of trading volume in predicting the price volatility. Using monthly index data, EGARCH model is utilized to test for volume effect. To estimate the EGARCH-based volatility, two different sets of region are applied for the monthly return. Strong evidence has been found towards housing turnover leading price volatility, this supports previous studies on financial sector(s). These findings also support that trading volume in the housing market contains information on investor sentiment which, in turn, has a valuation effect on the price.

식물공장 내 LED 광질과 광량이 딸기 런너 발생에 미치는 영향

류현욱(Hyenwook Ryu),이경희(Kyeong Hee Lee),이규회(Kyu Hoi Lee),이희두(Hee Doo Lee) 한국원예학회 2022 한국원예학회 학술발표요지 Vol.2022 No.11

주택시장의 유동성효과에 관한 연구

류현욱(Hyun-Wook Ryu),고성수(Sung-Soo Koh) 한국주택학회 2013 주택연구 Vol.21 No.3

금융시장에서 유동성은 투자자에게 중요한 변수이고 위험에 대한 보상의 개념으로 할인되거나 웃돈의 개념으로 가감된다. 호황기에는 거래가 많아지고 풍부해진 유동성은 가격을 견인하는 요인으로 작용한다. 반대로 불황기에는 여러 가지 요인으로 말미암아 거래가 위축되고 낮아진 유동성이 가격을 더욱 하락시킨다. 주택시장의 경우 기존연구들이 가격변화에 대한 거래량효과가 있을 수 있음을 시사하고 있다. 본 연구는 경기상승기에 주택시장의 중심가치가 투자적양상을 보이는 현상에 주목하고 금융투자시장에서 연구되고 있는 거래량효과에 대해 분석하였다. 거래량효과는 거래비용을 낮추어 자산가치를 높이는 유동성에 따른 위험요인이 요구수익률에 반영되는 유동성효과의 관점에서 고찰하였다. 회귀분석결과 유동성효과는 경기변동에 비대칭적으로 나타나 시장수요의 변화에 따라 투자에서 실수요중심으로 재편됨을 확인할 수 있었다. 부동산이 갖는 정보의 불완전성(imperfection)과 비유동성(illiquidity)은 자본시장에서 해당자산에 대한 투자를 꺼리게 하는 대표적 요인임에도 불구하고 해당 분야에 대한 연구가 부족한 실정이다. 본 연구는 주택경기침체기에 가격안정화에 대한 고민이 깊어지는 정부에 참고할만한 시사점을 제시했다는 측면에서 연구의 의미를 찾을 수 있다. 그러나 짧은 시계열의 한계와 함께 세분화된 시장간 또는 시장에 대한 향후연구는 현실적 요구에 좀더 부합할거라 본다. In the financial sector, many studies have attempted to explore the causes of and the effects of market liqudity where trading volume plays certain roles shifting price. In real estate field, more studies have focused on housing price and the consequences of turnover. This study rather sheds lights on liquidity effects on the residential housing market as observed in financial markets. Utilizing a regression model, it predicts that an increase in trading volume results in an increase in liquidity premium leading to higher value response coefficients. The study has several empirical implications that could be tested in future research. Comparative analysis of regional and/or size-wise complexes within a city or district would be useful to see how liquidity effect works in micro-market wise.

SIR 정보 모형의 금융기관 적용방안에 관한 연구

류현욱(Hyun-Wook Ryu) 인문사회과학기술융합학회 2018 예술인문사회융합멀티미디어논문지 Vol.8 No.8

의학분야에서는 오래전부터 전염병의 전파경로를 예측할 수 있는 모형개발을 위해 연구해왔다. 소수의 감염자가 인구집단 내 다수를 감염시키는 과정에서 감염자의 수가 어떤 속도로 증가되고 회복되는지를 통해 주어진 변수에 따른 전파 경로 및 확산속도 등을 파악하는 데 기여한 바 있다. 이는 교통네트워크를 추정하는 이학분야에서 정보의 흐름을 감지하는 SNS 등 경영과학 분야에 까지 연구 된 바 있다. 자산관리분야에서 자기주도형 투자자가 증가하고 있는 상황에서 세분화된 고객층에 맞춤형 대응의 효과성을 살펴보기 위해 SIR 모형을 적용했다. 미분방정식 기반의 동모형을 통해 고객관계관리(CRM) 시스템의 시뮬레이션 모형을 설정했다. 본 연구에서는 확장형 모형인 SEI로 정보흐름과 의사결정구간을 추정했으며 구간별로 어떤 전략적 접근법이 적정할 수 있는지에 대해 고찰했다. 그 결과 자산관리로의 잠재적 고객(일정 자산 보유)은 범용의 접근전략 수준에 따라 특정 서비스에 노출되며, 구체적인 시스템적 접근 내지는 콘텐츠 수준에 따라 특정 상품을 거래하는 속도에 해당하는 계수값 베타에 영향을 준다. 이는 나아가 재투자 의사결정 수준에 까지 영향을 줄 수 있게 된다. 본 연구는 자산관리 비즈니스 환경 변화와 고객관리체계를 살펴보고 정보의 흐름이 투자 내지는 재투자로 이어지는 흐름을 연구모형을 통해 분석하고 전략적 방향을 도출한다. In the field of biological medicine, researchers have studied to develop epidemic spreading model since quite a while ago. The studies show how a contagious disease could spread; the speed to which small number of progressor infect many others in the group of the susceptible, and how fast those are recovered. The prediction contributes to figure out what variables lead to the greatest influence(s). Studies have been conducted on scientific engineering area such as estimating transportation network, and on management science area such as detecting information flow(s) in Social Network Services. With the number of self-directed investors increased in wealth management field, this paper applies SIR model to examine the effectiveness of information provided via CRM system. The differential equation-based model is utilized in order to project simulation out of decision making process via information flow(s). The model is customized to SEI where a potential client is exposed to particular firm in wealth management industry, and makes investment decision as the firm approaches and provides ‘proper contents’ in a timely manner. The model suggests that Beta parameter increases the rate of individuals moving from susceptible status to a firm’s management sight; the exposed. Injecting proper contents to the exposed makes the exposed clients decide particular investment(s), and further leads to re-investment. This study presents the changes in the recent business environment of wealth management, and presents whether an information leads to investment decision.