Reduction of aromatic nitro compounds on Pd colloids prepared by g-irradiation

Chul-Gyun Hwang,Kim Sang-Ho,Oh Ji Hoon,Mi-Ran Kim,최성호 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.6

Poly(vinylpyrrolidone) (PVP), stabilized Pd colloids were successfully prepared by g-irradiation in aqueous solution without additional reducing agent. The ‘clean’ Pd colloid was used as catalysts for the reduction of 2-, 3-, 4-nitrophenol, 2,4,6-trinitrotoluene, and 4-nitrobenzo-15- crown in aqueous solution at room temperature. The reduction process was monitored by UV–Visible spectroscopy.

The Photochemical Reactivities of Benzenes Tethered to haloarene

Hwang, Chul Gyun,Sung, Dae Dong,Kim, Young Hee,Park, Yong Tae 東亞大學校附設基礎科學硏究所 1997 基礎科學硏究論文集 Vol.14 No.1

The syntheses and photoreactions of haloarenes, in which the aryl and haloaryl moieties are tethered by a simple alkyl group, were studied. For 2-benzyl-1-halobenzene, in which two aryl moieties were connected by methylene group, photoreduced product, diphenylmethane, was obtained along with the minor formation of the photocyclized product, fluorene, in acetonitrile solvent. For 1-halo-2-phenethylbenzene, in which two aryl moieties were connected by ethylene group, photocyclized products, 9,10-dihydrophenanthrene and phenanthrene, were obtained along with the minor formation of photoreduced product, bibenzyl, in acetonitrile solvent. The photoreaction selectivities in several solvent systems were studied: In cyclohexane, 2-benzyl-1-chlorobenzene was photoreduced more effective than 2-benzyl-1-bromobenzene; in the presence of NaOH, 1-halo-2-phenethylbenzenes gave 9,10-dihydrophenanthrene and, in the presence of toluene, they gave phenanthrene. A radical reaction mechanism is proposed for the explanation of the reactions. This study shows that the photoreaction of haloarene, in which haloaryl and aryl moieties are tethered by ethylene group, can be used for ring formation of 9,10-dihydrophenanthrene otherwise difficultly accessible.

EMTP를 이용한 배전자동화 기기의 모델링

황하균(Ha-Gyun Hwang),서훈철(Hun-Chul Seo),박광원(Kwang-Won Park),김철환(Chul-Hwan Kim) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7

배전계통에서 발생하는 각종 외란에 의한 배전자동화 기기의 영향을 분석하기 위하여 본 논문에서는 EMTP/MODELS를 이용하여 배전자동화 기기 중 Sectionalizer를 모델링하였다. 영구고장 및 순간 고장을 모의하여 Sectionalizer의 성능을 검증하였다. 그 결과 Sectionalizer는 Recloser의 차단 횟수를 고려하여 정확하게 동작하는 것을 확인할 수 있었다.

Relationship between the spatial distribution of coastal sand dune plants and edaphic factors in a coastal sand dune system in Korea

Hwang, Jeong-sook,Choi, Deok-gyun,Choi, Sung-chul,Park, Han-san,Park, Yong-mok,Bae, Jeong-jin,Choo, Yeon-sik The Ecological Society of Korea 2016 Journal of Ecology and Environment Vol.39 No.1

We conducted the study on the relationship between the distribution of coastal sand dune plants and edaphic factors from the shoreline to inland in sand dune ecosystem. The application of TWINSPAN classification based on 10 species, led to the recognition of three vegetative groups (A-C), which associated with their habitats (foredune, hummuck in semistable zone and stable zone). The associations were separated along soil gradient far from the seashore. The relationships between species composition and environmental gradients were explained by canonical correspondence analysis (CCA). Distance from the shoreline was an important indicator to determine soil properties (pH, total ion contents, sand particle sizes, organic matters and nitrogen contents) from the seaward area to inland area and distribution pattern of coastal sand dune plants. Group A is foredune zone, characterized by Calystegia soldanella; group included typical foredune species such as Elymus mollis, Carex kobomugi, Ixeris repens, C. soldanella and Glehnia littoralis. Group B on semi-stabilized zone was characterized by Vitex rotundifolia, a perennial woody shrub. This group was associated the proportion of fine sand size (100 to 250 μm). The results on the proportion of soil particle size showed a transition in sand composition, particularly with respect to the proportion of fine sand size that occurred from the foredune ridge at 32.5 m to the Vitex rotundifolia community at 57.5 m from the shoreline. Group C on stabilized zone was characterized by Zoysia macrostachya, Lathyrus japonicus and Cynodon dactylon and were associated soil organic matter and nitrogen contents. The spatial distribution of plants in the Goraebul coastal sand dune system may result from the interactions between the plant species and environmental heterogeneity.

Life Science : The coffee diterpene kahweol inhibits metastasis by modulating expressions of MMPs and VEGF STAT3 in activation

( Hyung Gyun Kim ),( Yong Pil Hwang ),( Eun Hee Han ),( Jae Ho Choi ),( Kwang Il Kwon ),( Young Chul Chung ),( Myung Ho Jeong ),( Tae Cheon Jeong ),( Won Ku Kang ),( Hye Gwang Jeong ) 영남대학교 약품개발연구소 2012 영남대학교 약품개발연구소 연구업적집 Vol.22 No.0

Kahweol, a coffee-specific diterpene, is reported to have anti-cancer properties. although its precise che mopreventive mechanism remains unclear. The aim of our study was to determine the effect of kahweol on anti-metastatic activities and the possible mechanisms. Kahweol inhibited the migration and invasion ability of various cancer cells in vitro and decreased the secretion of metalloproteinase (MMP)-2. MMP-9 and VEGF in cancer cells via suppression of STAT3 activation. Kahweol also exhibited an inhibitory effect on lung metastasis in the experimental B 16-F10 melanoma metastasis model. Moreover. kahweol inhibited migration and tube formation of endothelial cells in vitro. decreased the secretion of VEGD. and suppressed neovascularisation in Matrigel plugs in mice. Our findings demonstrate that kahweol inhibit metastasis through the disruption of SAT3 mediated transcription of the MMP and VEGF genes. ⓒ 2012 Elsevier Ltd. All rights reservec

Meso-Dihydroguaiaretic Acid Isolated from Saururus chinensis Inhibits Cyclooxygenase-2 and 5-Lipoxygenase in Mouse Bone Marrow-Derived Mast Cells

Tae Chul Moon,Chang Seob Seo,Kyungmi Haa,Jin Cheul Kim,Nam Kyung Hwang,Tae Gyun Hong,Jee Hyeun Kim,Do Hun Kim1,손종근,장현욱 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.5

Meso-dihydroguaiaretic acid (MDGA) is a medicinal herbal product isolated from the aerial parts of Saururus chinensis that inhibits the cyclooxygenase-2 (COX-2)-dependent phase of prostaglandin D2 (PGD2) generation in bone marrow-derived mast cells (BMMC) (IC50 9.8 μM). However, this compound did not inhibit COX-2 protein expression in BMMC at concentrations up to 30 μM, indicating that MDGA directly inhibits COX-2 activity. In addition, this compound consistently inhibited the production of leukotriene C4 (IC50 1.3 μM). These results demonstrate that MDGA inhibits both COX-2 and 5-lipoxygenase. Furthermore, this compound strongly inhibited the degranulation reaction in BMMC (IC50 11.4 μM). Therefore, this compound might provide a basis for novel anti-inflammatory drug development.

Usefulness of Double Vital Staining With 1% Fluorescein and 1% Lissamine Green in Patients With Dry Eye Syndrome

Yoon, Kyung-Chul,Im, Seong-Kyu,Kim, Hwang-Gyun,You, In-Cheon Lippincott Williams Wilkins, Inc. 2011 Cornea Vol.30 No.9

PURPOSE:: To determine the relative staining characteristics of the nasal and temporal conjunctiva as compared with other measures of dry eye and evaluate the qualitative clinical impression of the utility of the double vital staining with fluorescein and lissamine green. METHODS:: Ocular surface staining was performed with a mixture of 1% fluorescein and 1% lissamine green in 50 patients with dry eye (12 patients with Sjögren syndrome and 38 patients with non-Sjögren syndrome). Ocular surface disease index (OSDI), tear breakup time (BUT), and Schirmer test were evaluated. Digital photographs were taken after vital staining on the ocular surface, and the grade of staining in various areas was assessed. Correlation among the degrees of staining, OSDI, and ocular surface parameters was analyzed. RESULTS:: The nasal conjunctiva evidenced greater staining compared with the temporal conjunctiva and cornea (P = 0.04). Staining of the nasal conjunctiva showed significant correlation with OSDI (P < 0.01) and BUT (P = 0.03). Staining of the temporal conjunctiva correlated significantly with OSDI (P = 0.01), and staining of the cornea correlated with BUT (P = 0.02). CONCLUSIONS:: Double vital staining with 1% fluorescein and 1% lissamine green correlates with symptoms and some ocular surface parameters in patients with dry eye and helps to identify ocular surface changes easily. It may be a useful method for the diagnosis of dry eye and the assessment of the therapeutic effect in patients with dry eye syndrome.

The crystal structure of the second Z-DNA binding domain of human DAI (ZBP1) in complex with Z-DNA reveals an unusual binding mode to Z-DNA.

Ha, Sung Chul,Kim, Doyoun,Hwang, Hye-Yeon,Rich, Alexander,Kim, Yang-Gyun,Kim, Kyeong Kyu National Academy of Sciences 2008 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.105 No.52

<P>Mammalian DAI (DNA-dependent activator of IFN-regulatory factors), an activator of the innate immune response, senses cytosolic DNA by using 2 N-terminal Z-DNA binding domains (ZBDs) and a third putative DNA binding domain located next to the second ZBD. Compared with other previously known ZBDs, the second ZBD of human DAI (hZbeta(DAI)) shows significant variation in the sequence of the residues that are essential for DNA binding. In this article, the crystal structure of the hZbeta(DAI)/Z-DNA complex reveals that hZbeta(DAI) has a similar fold to that of other ZBDs, but adopts an unusual binding mode for recognition of Z-DNA. A residue in the first beta-strand rather than residues in the beta-loop contributes to DNA binding, and part of the (alpha3) recognition helix adopts a 3(10) helix conformation. The role of each residue that makes contact with DNA was confirmed by mutational analysis. The 2 ZBDs of DAI can together bind to DNA and both are necessary for full B-to-Z conversion. It is possible that binding 2 DAIs to 1 dsDNA brings about dimerization of DAI that might facilitate DNA-mediated innate immune activation.</P>

S-Allyl cysteine attenuates free fatty acid-induced lipogenesis in human HepG2 cells through activation of the AMP- activated protein kinase-dependent pathway

( Yong Pil Hwang ),( Hyun Gyun Kim ),( Jae Ho Choi ),( Minh Truong Do ),( Young Chul Chung ),( Tae Cheon Jeong ),( Hye Gwang Jeong ) 영남대학교 약품개발연구소 2013 영남대학교 약품개발연구소 연구업적집 Vol.23 No.0

S-Allyl cysteine (SAC), a nontoxic garlic compound, has a variety of pharmacological properties, including antioxidant and hepatoprotective properties. In this report, we provide evidence that SAC prevented free fatty acid (FFA)-induced lipid accumulation and lipotoxicity in hepatocytes. SAC significantly reduced FFA-induced generation of reactive oxygen species, caspase activation and subsequent cell death. Also, SAC mitigated total cellular lipid and triglyceride accumulation in steatotic HepG2 cells. SAC significantly increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in HepG2 cells. Additionally, SAC down-regulated the levels of sterol regulatory element binding protein-1 (SREBP-1) and its target genes, including ACC and fatty acid synthase. Use of a specific inhibitor showed that SAC activated AMPK via calcium/calmodulin-dependent kinase kinase (CaMKK) and silent information regulator T1. Our results demonstrate that SAC activates AMPK through CaMKK and inhibits SREBP-1-mediated hepatic lipogenesis. Therefore, SAC has therapeutic potential for preventing nonalcoholic fatty liver disease. ⓒ2013 Elsevier lnc. Arl rights resetved.

부산 3호선 전동차 브레이크 디스크 및 차축보스시트 가공방법 개선

김상균(Sang Gyun Kim),박희철(Hee Chul Park),황석진(Seug Jin Hwang),김심인(Sim In Kim) 한국철도학회 2016 한국철도학회 학술발표대회논문집 Vol.2016 No.5

2005년도에 개통한 부산 3호선 전동차의 브레이크 디스크는 반복적인 마찰제동으로 열변형과 편마모가 발생되어 제동 시 소음발생 및 승차감 불량, 제동성능저하로 정위치정차 불량 등을 야기시킬 수 있다. 차축 보스시트를 벨트 샌더로 수동연마 시 가공면에 가해지는 힘의 불균형으로 형상오차가 발생되고 또한 저널선반 척 죠의 물림속도차이에 의해 가공오차가 발생한다. 따라서 차축에 차륜압입 시 차륜 내경 및 차축 보스시트가 손상되어 전동차 안전운행에 위험이 발생될 수 있다. 본 논문은 디스크 삭정 시 발생되는 분해 및 조립시간, 작업인원 및 제작비용을 최소화시킬 수 있는 디스크 삭정전용 지그를 제작하고, 저널선반엔 차축 보스시트를 자동으로 가공할 수 있는 프로그램 설치와 센터고정 지그 및 어댑터를 제작하여 형상 및 가공오차 발생을 최소화시킨 내용이다. The brake disk of Busan metro line 3 was opened in 2005. It occurred for thermal variation and one-sided worn out because of repeated friction braking of brake disk that can cause noise during braking, uncomfortable ride and inaccurate train stop occurring by braking degradation. When wheel axle boss seat is hand-grinded that uses belt sander, it applies an imbalance force on machine’s surface that can cause error. Also processing error can occur by difference in contact speed of journal lathe chuck jaw. Therefore when pressing and fitting a wheel in the wheel axle, The metro can occur danger in safety driving if the diameter of the wheel and wheel axle boss seat is damage. This dissertation made to cut chamfer into zig for brake disc surface that can minimize to disassemble and assemble time, workers, and cost. Also, It can minimize the error of the occurrence of the shape and processing by installing program about automatically processing to wheel axle boss seat on journal lathe and making center stationary jig and adapter.