Ruthenium-Catalyzed C–H Activation/Cyclization for the Synthesis of Phosphaisocoumarins

Park, Youngchul,Jeon, Incheol,Shin, Seohyun,Min, Jiae,Lee, Phil Ho American Chemical Society 2013 Journal of organic chemistry Vol.78 No.20

<P>An efficient and cost-effective ruthenium-catalyzed oxidative cyclization of phosphonic acid monoesters or phosphinic acids with alkynes has been developed for the synthesis of a wide range of phosphaisocoumarins in good to excellent yields under aerobic conditions. A multitude of arylphosphonic acid monoesters and arylphosphinic acids having electron-donating and -withdrawing groups were oxidatively cyclized. Various diarylacetylenes, dialkylacetylenes, and alkylarylacetylenes effectively underwent the ruthenium-catalyzed oxidative cyclization. A substrate possessing benzoic acid as well as a phenylphosphonic monoester moiety was smoothly cyclized with hex-3-yne to afford a compound having both isocoumarin and phosphaisocoumarin moieties. Alkenylphosphonic monoester afforded phosphorus 2-pyrone through oxidative cyclization with alkyne. Competition experiments between diaryl- and dialkylalkynes and between diarylacetylenes having <I>p</I>-methoxy and <I>p</I>-chloro groups gave results which showed that the present oxidative cyclizations were not affected by the electronic effects of alkynes. Mechanistic studies revealed C–H bond metalation to be the rate-limiting step.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2013/joceah.2013.78.issue-20/jo401608v/production/images/medium/jo-2013-01608v_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo401608v'>ACS Electronic Supporting Info</A></P>

Fatigue Analysis of Composite Helicopter Hub Flexure by Meta models

Youngchul Park,Jungsun Park,Youngjung Kee 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-

As new helicopter mission is more demanding, composite materials are used for a hub flexure of light weighted rotor system. The composite flexure has advantage in designing hingeless rotor system. The flexure resists flapping, fathering and lead-lagging moments as hinges. Due to the three dimensional hinges, the flexure has a very complicated structure to do analysis. In this study, the flexure is modeled as a laminated structure for the analysis of composite material. In the structural analysis. the static failure is determined by the maximum stress theory and Tsai-Hahn failure criterion. Moreover, the fatigue life is estimated by an in-house fatigue life estimation code for composite materials. The fatigue analysis requires load spectrums generated by FELIX. Fatigue experimental data are generated by one meta (approximate) models to establish the S-N curves for each layers. The meta model may generate simpler regression curve than general regression method, particularly for nonlinear problems. To pursue reliability analysis, the coefficients of determination method are compared between experimental points and regression curves. Thus, the fatigue life can be estimated with more accuracy. This analysis can be used for primary helicopter structural development.

Caffeine synthesis by exogenous methyltransferase genes in rice confers a broad-spectrum resistance against biotic stresses

Youngchul Yoo,Jong Chan Park,Joo-Mi Yoon,Hyemin Lim,Gang-Seob Lee,Sang-Won Lee 한국육종학회 2013 한국육종학회 심포지엄 Vol.2013 No.07

Plants have evolved a set of protecting mechanisms against pathogens, which include secondary metabolites and induced defense responses to pathogen attack. The biological role of purine alkaloids including caffeine is largely unknown. It has been proposed that caffeine confers a resistance against pathogenic bacteria and herbivores. We, in this study, tested direct effects on the growth of rice pathogenic microbes, Xanthomonas oryzae pv. oryzae (Xoo) causing a bacterial leaf blight and Magnaporthe grisea (M. grisea) causing a rice blast. Cell growth of Xoo and M. grisea were significantly retarded in presence of high concentration (2mM) of caffeine. Exogenous caffeine (5mM) induced resistance of wild type rice (cv. Dongjin, susceptible to Xoo and M. grisea) against those pathogens. These results indicated that caffeine enhanced the basal resistance to infection with Xoo. In addition, expression of pathogenesis-related (PR) genes was tested in the caffeine treated rice to elucidate the acquired resistance by caffeine, resulted in induction of PR genes including OsPR1a and OsPrb1. We have generated a transgenic rice producing caffeine by introduction of three N- methyltransferase genes (CaXMT1, CaMXMT1, CaDXMT1) identified from coffee plant. The transgenic rice successfully expressed the three genes, synthesized caffeine up to 5ug/g and showed enhanced resistance to Xoo. We also observed that transcripts of PR genes such as the OsPR1a and OsPrb1 encoding PR-1 type pathogenesis-related protein increased in the caffeine-producing rice. These result showed that caffeine is likely to act a powerful factor to increase level of rice defense as a natural and non-harmful metabolite.

Modeling water flow on Façade

Park, Chul Woong,Park, Jaeman,Kim, Naree,Kim, Youngchul Elsevier 2018 AUTOMATION IN CONSTRUCTION - Vol.93 No.-

<P><B>Abstract</B></P> <P>This study aims to develop a novel method by which visually to simulate water flow paths on building façades. Rainwater runoff affects the designs of façades in terms of safety and aesthetics because runoff leaves dirt and stains on an aesthetic façade. The first step is to review flow simulation algorithms and identify its limitations in fluid visualization research on flow path simulations. The second step is to review an existing CFD program to identify its limitations, and then establish the goals of the newly proposed method. The third step is to identify the properties and behaviors of water on a surface, including basic fluid mechanics to establish the mechanical relationship between the water and the façade material. The fourth step involves an experiment with water flows to reveal their characteristics based on the literature. The fifth step is to develop an algorithm which visually simulates water flows on a building façade. As a result, “Rainflow01” and “Rainflow02” are developed based on the open-source Grasshopper component “Drainage Polysurface” and Rhino. Rainflow01 and Rainflow02, which work based on the angle variation and critical sliding angle of the water path, present an innovative approach for predictions of water paths over a façade.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Water flow paths are visually simulated. </LI> <LI> Water behaviors on a façade are classified based on a mechanical relationship. </LI> <LI> The proposed algorithms are implemented using Grasshopper and Rhino. </LI> </UL> </P>

Design and Implementation of Math-Solving Robot

Youngchul Park,Hyungseok Lee,Joonpyo Hong,Joonsung Lee,Taesan Min,Hyeun Jeong Min,Hyo-Sang Lim,Hyoungsoon Kim 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

This paper presents the design of a math-solving robot which has many potential applications in service, entertainment, and educational robotics. We design a robot scanning and recognizing a printed math problem on a paper and then writing an answer on it. We specifically attempt to solve magic square puzzles and compute simple calculation. Controlling motors and recognizing targets from low-cost sensors are very challenging; however, we address the design of our robot to generate stable and effective motions, built with a Lego Mindstorms EV3 in addition to robust sensing ability through its color sensor in our software design. We also present a linear system method and rank analysis in order to decide if the given puzzle has a unique solution, more than one solution, or no solution. Through real robot experiments with quantitative and qualitative analysis regarding scanning, matching, and algorithm, we demonstrate our robot solves given magic square problems and simple calculations.

Study of resistance in rice innate immunity by non-RD kinases

Youngchul Yoo,Jong-Chan Park,Joo-Mi Yoon,Min-Young Song,Chi-Yeol Kim,Jong-Seong Jeon,Sang-Won Lee 한국육종학회 2012 한국육종학회 심포지엄 Vol.2012 No.07

Disease is one of the significant factors to damage for the crop productivity, including rice. Although there are many methods to avoid from several diseases such as chemical pesticides and biological treatments, it has been appreciated that the most economical and environmentally effective method of disease control is application of resistance genes. A survey (Dardick & Ronald, 2006) reported that plant kinome has a small number of non-RD kinase (nRDK) (4-29% of total kinase), all known or predicted pattern recognition receptors (PRRs) fall into the class. We here introduce a strategy to identify rice resistance genes that are probably encoding PRRs. We selected 130 nRDK genes by combinational analysis of QTL and bioinformatics, 61 of rice mutant lines of 130 candidates inoculated by Xanthomonas oryzae pv. oryzae (Xoo) and Magnaporthe grisea. (M. grisea), and disease progression was monitored. Lesion lengths of the activation mutant lines for nRDK-08 and nRDK-18 genes reduced more than 34% compared to wild type of rice (Dongjin) and other mutant lines. The nRDK-03 and nRDK-17 gene activation rice line had remarkably smaller lesion lengths by M. grisea infection. Our results suggest that a reverse genetic approach using bioinformatics and T-DNA tagging system successfully identified nRDK genes conferring a resistance against Xoo and M. grisea.

The Validities and Efficiencies of Korean ADHD Rating Scale and Korean Child Behavior Checklist for Screening Children with ADHD in the Community

JongIl Park,ShiHa Shim,Myeongmi Lee,YoungEun Jung,TaeWon Park,SeonHee Park,YongJin Im,JongChul Yang,YoungChul Chung,SangKeun Chung 대한신경정신의학회 2014 PSYCHIATRY INVESTIGATION Vol.11 No.3

Objective-The purpose of this study is to examine the validity of primary screening tools for attention deficit hyperactivity disorder (ADHD) in a community-based sample of children using the Korean version of the Child Behavior Checklist (K-CBCL) and the Korean version of the ADHD Rating Scale (K-ARS). Methods-A large-scale community-based study for ADHD screening was conducted in the Jeollabuk province in the Republic of Korea. In 2010–2011, we surveyed a total of 49,088 first- and fourth-grade elementary school students. All of the participants in this study were assessed by the K-ARS-Parent version (K-ARS-P) and the K-ARS-Teacher version (K-ARS-T) as the primary screening instruments. The Diagnostic Interview Schedule for Children Version IV (DISC-IV) was used for confirming the diagnosis of ADHD. DISC-IV was administered to subjects who received top 10% scores in the K-ARS-P or K-ARS-T tests. Results-Of the 3,085 subjects who completed the DISC-IV, 1,215 were diagnosed as having ADHD. A reasonable level of sensitivity, specificity, and negative predictive value were obtained when the total K-ARS-P scores were ≥90th percentile. The positive predictive value and specificity increased significantly when the total K-ARS-P scores were ≥90th percentile, T scores were ≥60 in the attention problems of K-CBCL, and T scores were ≥63 in the total problems of K-CBCL Conclusion-These results suggested that the K-ARS-P could effectively serve as a primary screening tool to identify elementary school children with ADHD in the community. Also, there might be some increment in the effectiveness of K-ARS-P when combined with KCBCL-A and K-CBCL-T as a secondary screening tool.

특성함수와 피로해석을 이용한 로워컨트롤암의 형상최적설계

박영철(Youngchul Park),이동화(Donghwa Lee) 한국자동차공학회 2005 한국 자동차공학회논문집 Vol.13 No.1

유한 요소법을 이용한 로우컨트롤암의 피로수명 평가

박영철(Youngchul Park),이동화(Donghwa Lee) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Requirement terms in the development of automobile part are progressed about light weight, damage prevention by fatigue, and safety of product. Already, The previous study was gained suitably the good result about light weight in the expected period of this time when they changed the metal of lower control arm. But in the case of automobile part, it was concerned with life of people. And in the result, the fatigue life is very important. In this requirement, when we drive a car, our car is applied to the cycle load. Estimation of the fatigue properties must have respect to the design process. In these days of rapidly growth. this study is help to competition ability of automobile industry and will bring forth a large safety property and fast development effect.

대구 지하철 교통수요 예측

박영철(Park Youngchul) 계명대학교 사회과학연구소 2004 한국사회과학연구 Vol.23 No.1

If we forcast the demand for the traffic of the subway system in Daegu, we can efficiently manage the manpower and the facilities of the city. The forcasting is implemented through autoregressive-moving average process and Winters' additive seasonal exponential smoothing. If it had not been for the arson in the subway in 1993, the daily transportation would slightly have increased. The demand for the subway system is high in spring and in fall, and low in summer and in winter.