High Performance and Stability of Micropatterned Oxide-Passivated Photoanodes with Local Catalysts for Photoelectrochemical Water Splitting

Oh, Seungtaeg,Oh, Jihun American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.1

<P>A new passivation strategy for an oxygen evolving Si photoanode for efficient and stable photoelectrochemical (PEC) water splitting is presented. In our Si photoanode structure, to eliminate the Si/water interface, the Si is stabilized with a thick insulating and chemically inert SiO2 film and locally defined electrocatalysts on the Si surface. The stabilized p(+)n-Si photoanode with SiO2 film and micropatterned Ni catalysts produced photocurrent densities of 27 mA cm(2) at water oxidation potential without corrosion for 24 h under water oxidation conditions. In addition, we provide a device modeling of our Si cell, i.e., an integrated photovoltaics-electrolyzer cell, to quantitatively assess the interplay between optical shadowing and catalytic performance, as a function of the coverage and characteristics of electrocatalysts on the water oxidation reaction during PEC water splitting. Design principles for high performance oxygen evolving Si photoanodes are presented based on the device modeling.</P>

Effectiveness of Acupuncture for Laryngopharyngeal Reflux Disease: A Systematic Review and Meta-Analysis

Jihun Oh,Jaewoo Yang,Jungmin Yang,Minsoo Kang,Sukyoung Kim,Minjun Lee,Jinwoong Lim 대한침구의학회 2023 대한침구의학회지 Vol.40 No.3

Laryngopharyngeal reflux (LPR) disease is a condition in which the stomach contents return to the larynx and pharynx via the esophagus, causing mucosal injury. While conventional treatments, such as proton pump inhibitors, have limitations, acupuncture has been shown to reduce LPR symptoms. However, its effectiveness has not been systematically assessed. This study aimed to systematically evaluate the effectiveness of acupuncture in treating LPR. We review 10 electronic databases with a consistent search strategy, and 2 independent reviewers screened the articles based on the inclusion and exclusion criteria. This study selected and analyzed 7 randomized controlled trials after the screening to assess primary outcomes, including reflux symptom index and reflux finding score, and secondary outcomes, including upper and lower esophageal sphincter pressure. The results revealed the statistically significant effectiveness of acupuncture in combination with conventional treatment in reducing LPR symptoms compared with conventional treatment alone. The most commonly used acupuncture points were CV22, ST36, and LR3. However, the meta-analysis demonstrated low reliability, as assessed using the GRADE Tool. Further research is needed to improve the evidence and draw clear conclusions regarding the clinical use of acupuncture for treating LPR.

Computation Study on the Thermodynamic Energies of HyBRID Dissolution Reaction Considering Cu-Hydrazine Complex Formation

Jihun Oh,Young-Kyu Han 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

Decontamination is one of the important processes for dismantling nuclear power plants. The purpose of decontamination is to reduce the radiation levels of contaminated nuclear facilities, ensuring the safety of workers involved in decommissioning and minimizing the amount of radioactive waste. In this study, we investigate the reaction mechanisms and their thermodynamic energies of the HyBRID (Hydrazine-Based Reductive participated metal Ion Decontamination) process for decontamination of the primary coolant system of a nuclear power plant. We computed the thermodynamic properties of HyBRID dissolution mechanisms in which corrosion metal oxides accumulated in the primary coolant systems along with radionuclides are dissolved by HyBRID decontamination agents (H2SO4/N2H4/CuSO4). The HyBRID reaction mechanism has been studied using a commercial database (HSC Chemistry®), but Cu ions have been used instead of Cu-hydrazine complexes when calculating reactions due to the absence of thermodynamic properties for Cu-hydrazine complexes. To address this limitation, we supplemented the quantum calculations with Cu-hydrazine complexes using the density functional calculations. It is intended to simulate a more practical reactions by calculating the reactions considering Cu-hydrazine complexes, and to improve understanding of the HyBRID dissolution reactions by qualitatively and quantitatively comparing the reactions without considering the complex formation.

An Optically and Electrochemically Decoupled Monolithic Photoelectrochemical Cell for High-Performance Solar-Driven Water Splitting

Oh, Seungtaeg,Song, Hakhyeon,Oh, Jihun American Chemical Society 2017 Nano letters Vol.17 No.9

<P>Photoelectrochemical (PEC) cells have attracted much attention as a viable route for storing solar energy and producing value-added chemicals and fuels. However, the competition between light absorption and electrocatalysis at a restrained cocatalyst area on conventional planar-type photo electrodes could limit their conversion efficiency. Here, we demonstrate a new monolithic photoelectrode architecture that eliminate the optical-electrochemical coupling by forming locally nanostructured cocatalysts on a photoelectrode. As a model study, Ni inverse opal (IO), an ordered three-dimensional porous nanostructure, was used as a surface-area-controlled electrocatalyst locally formed on Si photoanodes. The optical-electrochemical decoupling of our monolithic photoanodes significantly enhances the PEC performance for the oxygen evolution reaction (OER) by increasing light absorption and by providing more electrochemically active sites. Our Si photoanode with local Ni IOs maintains an identical photolimiting current density but reduces the overpotential by about 120 mV compared to a Si photoanode with planar Ni cocatalysts with the same footprint under 1 sun illumination. Finally, a highly efficient Si photoanode with an onset potential of 0.94 V vs reversible hydrogen electrode (RHE) and a photocurrent density of 31.2 mA/cm(2) at 1.23 V vs RHE in 1 M KOH under 1 sun illumination is achieved with local NiFe alloy IOs.</P>

상반신 추적 기술 기반 감정 인식 시스템

오지훈(Jihun Oh),유선진(Sunjin Yu),이민규(Minkyu Lee),임우택(Wootaek Lim),안충현(ChungHyun AHN),이상윤(Sangyoun Lee) 한국방송·미디어공학회 2013 한국방송공학회 학술발표대회 논문집 Vol.2013 No.6

적응형 결정 트리를 이용한 국소 특징 기반 표정 인식

오지훈(Jihun Oh),반유석(Yuseok Ban),이인재(Injae Lee),안충현(Chunghyun Ahn),이상윤(Sangyoun Lee) 한국통신학회 2014 韓國通信學會論文誌 Vol.39 No.2(통신이론)

본 논문은 결정 트리(Decision tree) 구조를 기반으로 한 표정 인식 방법을 제안한다. ASM(Active Shape Model)과 LBP(Local Binary Pattern)를 통해, 표정 영상들의 국소 특징들을 추출한다. 국소 특징들로부터 표정들을 잘 분류할 수 있는 판별 특징(Discriminant feature)들을 추출하고, 그 판별 특징들은 모든 조합의 각 두 가지 표정들을 분류시킨다. 분류를 통해 얻어진 정인식의 합을 통해, 정인식 최대화 기반 국소 영역과 표정 조합을 결정한다. 이 가지 분류들을 종합하여, 결정 트리를 생성한다. 이 결정 트리 기반 표정 인식률은 약 84.7%로, 결정 트리를 고려하지 않은 방법보다, 더 좋은 인식 성능을 보였다. This paper proposes the method of facial expression recognition based on decision tree structure. In the image of facial expression, ASM(Active Shape Model) and LBP(Local Binary Pattern) make the local features of a facial expressions extracted. The discriminant features gotten from local features make the two facial expressions of all combination classified. Through the sum of true related to classification, the combination of facial expression and local region are decided. The integration of branch classifications generates decision tree. The facial expression recognition based on decision tree shows better recognition performance than the method which doesn"t use that.

머신러닝을 적용한 주택가격 추정모형

오지훈(Jihun Oh),김정섭(Jeongseob Kim) 한국주택학회 2017 한국주택학회 학술대회 발표논문집 Vol.2017 No.2

헤도닉 모형은 재화에 내재되어 있는 특성을 통해 가격을 추정하는 모형으로 주택시장분석에 널리 사용되어 왔다. 그러나 헤도닉 모형을 사용한 많은 연구들이 선형회귀분석을 추정기법으로 활용하면서 선형적합이 가지는 여러 한계점이 나타났다. 대표적으로 설명변수의 영향력이 비선형적으로 나타나는 경우, 선형회귀모형 상에서는 이러한 비선형적 관계를 포착하기 어렵다. 이에 따라 설명변수를 조작하는 방식으로 변수들의 비선형적 영향력을 통제하고 선형적합에 따른 편의성을 줄이고자 하는 노력들이 이어졌다. 그러나 이러한 방식은 데이터 자체에 기반한 방식이라기보다는 경험적 사실에 더 중점을 두고 있다는 점에서 한계가 있다. 따라서 본 연구에서는 머신러닝 기법 중 하나인 MARS(Multivariate Adaptive Regression Spline)를 활용하여 주택 특성들이 가격에 반영되는 양상을 보다 객관적으로 분석할 수 있는 헤도닉 모형을 제시하고자 한다. MARS는 관측치의 분포에 따라 비선형적으로 회귀식을 추정하는 기법으로, 주택가격 결정요인들의 변곡점(inflection point)을 포착할 수 있다는 점이 장점이다. 분석은 2014~2016년 사이 서울시에서 거래된 개별 아파트 자료를 대상으로 한다. 종속변수는 아파트 실거래가를, 독립변수는 아파트의 물리적 특성을 위주로 구축하였다. 분석 결과, MARS는 기존의 선형회귀분석 기반의 주택가격 추정모형과 비교하여 설명력이 보다 우수한 것으로 나타났다. 또한 아파트 물리적 특성 변수들의 비선형적 영향력이 나타나는 지점, 대표적으로 경과년도의 경우 시간이 지나면서 가격이 감소하다가 재건축 수요로 인해 가격이 다시 증가하는 지점을 변곡점을 통해 발견할 수 있었다.

Morphology-controlled Au nanostructures for efficient and selective electrochemical CO2reduction

Kim, Jaehoon,Song, Jun Tae,Ryoo, Hyewon,Kim, Jin-Gyu,Chung, Sung-Yoon,Oh, Jihun The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.12

<P>Electrochemical conversion of CO2has been considered as a promising method for producing value-added chemicals. Here, we report a systematic study on the formation of Au nanostructures<I>via</I>electroreduction of anodic Au(OH)3for selective CO production by an electrochemical CO2reduction reaction (CO2RR). First, we demonstrate the influence of electrochemical process parameters on the formation of Au nanostructures and Au(OH)3. The Au nanostructure morphologies can be tuned into either pore-like or pillar-like structures by controlling the anodic potential and/or reduction current density. This distinctive morphology is associated with the electric-field-assisted transport of Au<SUP>3+</SUP>at/near the Au(OH)3/Au interface. Additionally, we report the catalytic activity of the morphology-controlled Au nanostructures in the CO2RR. Both Au nanostructures exhibit significantly higher CO selectivity at a low overpotential than the untreated Au film due to the high density of grain boundaries which can assist with faster stabilization of the CO2˙<SUP>−</SUP>intermediate. In particular, the pore-like structures have a higher CO selectivity than the pillar-like ones at 280 mV overpotential although the pillar-like Au nanostructures have a higher CO selectivity and CO producing current density at high overpotentials. This potential-dependent CO2RR performance of the two different Au nanostructures is discussed.</P>

Nonisothermal crystallization behaviors of nanocomposites prepared by in situ polymerization of high-density polyethylene on tungsten oxide particles

Oh, Kyounghwan,Chua, Wei Huan,Park, Sung Eun,Kim, Jihun,Kwak, Soonjong,Kim, Sehyun,Seo, Yongsok Springer-Verlag 2015 Macromolecular Research Vol.23 No.3

Prognostic Value of the Microsatellite Instability Status in Patients With Stage II/III Rectal Cancer Following Upfront Surgery

Oh, Chung Ryul,Kim, Jeong Eun,Kang, Jihoon,Kim, Sun Young,Kim, Kyu-pyo,Hong, Yong Sang,Lim, Seok-Byung,Yu, Chang Sik,Kim, Jin Cheon,Kim, Jihun,Jang, Se Jin,Kim, Tae Won Elsevier 2018 Clinical colorectal cancer Vol.17 No.4

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>We investigated whether the microsatellite instability (MSI) status affects the survival outcomes in patients with stage II/III rectal cancer who have undergone an upfront curative resection.</P> <P><B>Patients and Methods</B></P> <P>A total of 1103 patients with curatively resected stage II/III rectal cancer who had available polymerase chain reaction-based MSI results were included in the final analysis.</P> <P><B>Results</B></P> <P>Twenty-four (2.2%) patients in the total cohort were found to be MSI-high (MSI-H). In univariate analysis, neither disease-free survival (DFS) nor overall survival (OS) demonstrated significant differences between patients with MSI-H tumors and those with MSI-low (MSI-L) or microsatellite stable (MSS) tumors. The 5-year DFS rate was 78.0% in MSI-H patients and 69.9% in MSI-L/MSS patients (hazard ratio [HR], 0.84; 95% confidence interval [CI], 0.35-2.02; <I>P</I> = .689). The 5-year OS rates for MSI-H and MSI-L/MSS patients were 84.0% and 83.1%, respectively (HR, 0.86; 95% CI, 0.27-2.69; <I>P</I> = .790). By multivariate analysis, the MSI status did not affect either the DFS (HR, 1.00; 95% CI, 0.40-2.47; <I>P</I> = .994) or OS (HR, 0.85; 95% CI, 0.26-2.73; <I>P</I> = .778).</P> <P><B>Conclusions</B></P> <P>MSI-H tumors are rarely observed in rectal adenocarcinoma, and the MSI status may not affect the survival outcome in patients with a resected rectal cancer.</P>