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Bednar Tumor of the Chest Wall : a case report
Choi, Dong-Youl,Lim, Sung-Chul 朝鮮大學校 附設 醫學硏究所 2009 The Medical Journal of Chosun University Vol.33 No.S
Bednar tumor is a rare variant of dermatofibrosarcoma protuberans that is characterized by slow growth and a unique storiform pattern and in some cases by the presence of melanin pigment. We recently experienced a case of Bednar tumor arising in the left chest wall. A 25-year old man came to the hospital with a chief complaint of 2.5 cm sized palpable mass on the chest wall. Onset time was unknown, but size of tumor increased gradually. An excisional biopsy was done and disclosed a well circumscribed tumor consisted of spindle cells arranged in a storiform pat-tern with some scattered melanin pigmented cells. There were some nuclear atypia and a few atypical mitoses. This tumor invaded extensively peritumoral adipose tissue therefore the boundary of the tumor was uncertain. Immunohistochemically, tumor cells have immunoreactivity for CD34 and C-kit, but not for S-100, desmin and HMB-45. These findings suggested that the mass was consistent with the Bednar tumor. We herein report a case of Bednar tumor with review of the literature.
Choi, Min-Ki,Sung, Youl-Moon,Park, Min-Woo American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.2
<P>We report a TiO2 nanotubes (NTs)-based Electrochemical luminescence (ECL) cell. The ECL cell was fabricated using the electrode of TiO2 NTs and Ru(II) complex (Ru(bpy)2+(3)) as a luminescence materials. The fabricated ECL cell is composed of F-doped SnO2 (FTO) glass/Ru(II)/TiO2 NTs/Ti plate. At a bias voltage of 3 V, the measured ECL efficiencies were 0 Im/W for cell without NTs, 0.03 Im/W for NTs-6.5 µm, 0.07 Im/W for NTs-8 µm and 0.1 Im/W for NTs-10 µm, respectively. The use of Ti02 NTs increases ECL intensities by about 2 times compared to the typical ECL cell without the use of TiO2 NTs.</P>
Acute and Subchronic Inhalation Toxicity of n-Octane in Rats
Sung, Jae-Hyuck,Choi, Byung-Gil,Kim, Hyeon-Yeong,Baek, Min-Won,Ryu, Hyun-Youl,Kim, Yong-Soon,Choi, Young-Kuk,Yu, Il-Je,Song, Kyung-Seuk Occupational Safety and Health Research Institute 2010 Safety and health at work Vol.1 No.2
Objectives: We have investigated the toxic effects of the inhalation of subchronic and acute levels of n-octane. Methods: The rats were exposed to n-octane of 0, 2.34, 11.68 and 23.36 mg/L (n = 5 rats/group/gender) in an acute inhalation test (Organization for Economic Co-operation and Development (OECD) TG 403), or to 0, 0.93, 2.62 and 7.48 mg/L (n = 10 rats/group/gender) for a subchronic inhalation test (OECE TG 413), to establish a national chemical management system consistent with the Globally Harmonized Classification System (GHS). Results: Acutely-exposed rats became lethargic but recovered following discontinuation of inhalation. Other clinical symptoms such as change of body weight and autopsy finds were absent. The LC50 for the acute inhalation toxicity of n-octane was determined to exceed 23.36 mg/L and the GHS category was 'not grouping'. Subchronically-treated rats displayed no significant clinical and histopathological differences from untreated controls; also, target organs were affected hematologically, biochemically and pathologically. Therefore, the no observable adverse effect level was indicated as exceeding 7.48 mg/L and the GHS category was 'not grouping' for the specific target organ toxicity upon repeated exposure. Conclusion: However, n-octane exposure should be controlled to be below the American Conference of Industrial Hygienists recommendation (300 ppm) to prevent inhalation-related adverse health effects of workers.
Choi, Wahn Soo,Seo, Dong Wan,Chang, Man Sik,Han, Jeung Whan,Hong, Sung Youl,Paik, Woon Ki,Lee, Hyang Woo 성균관대학교 약학연구소 1998 成均藥硏論文集 Vol.10 No.1
The presence of L-arginine methylester (AME), L-arginine ethylester (AEE), or N-nitro-L-arginine methylester (NAME) in the growth media of Staphylococcus aureus increased the nitric oxide synthase (NOS) activity approximately 5-to 14-fold. The increase of NOS activity was confirmed by two assay methods, namely assaying the formation of L-[^3H] citrulline from L-[^3H] arginine and NO formation. The increase of NOS activity was most likely due to increased de novo synthesis, demonstrated by Western immunoblot analysis. The addition of methanol to the culture medium also increased the NOS activity as much as that found with the above three compounds. Evidence is presented to show that AME, AEE, or NAME gave rise to the formation of methanol in vivo by the action of intracellular esterase(s) and that methanol is subsequently involved in the induction of NOS in this bacterial system.
Youl-Kwan Sung,Yoonmi Lee,Il-Seon Choi 한국교육개발원 2016 KEDI Journal of Educational Policy Vol.13 No.2
This article analyzes the pedagogical practices of an emerging school change project in South Korea called the Hyukshin School movement. Using Yrj? Engestr?m’s cultural historical activity theory and Basil Bernstein’s framework of pedagogical practice as theoretical lenses, we investigate experiences of this school change project to answer research questions regarding the contradictions teachers perceive in their pedagogical practices, the mediational tools they use and how they learn through school change experiences. The data were obtained through interviews with participating teachers, observations, and other meaningful artifacts. Teachers in this movement view test-driven competition-based pedagogy as the main contradiction that obstructs democratic and collaborative education. In response to this contradiction, teachers in Hyukshin Schools have created various mediation tools, such as a new school vision, a U-shaped seating arrangement, collaborative school rule-making, and a whole-school approach to the sharing of classroom teaching. Our findings in this study help outline the relationship between teachers’ learning through new practices and school change activity.
Choi, Jaeho,Park, Sung-Kyun,Hwang, Ho-Young,Huh, Joo-Youl Elsevier 2015 Acta materialia Vol.84 No.-
<P><B>Abstract</B></P> <P>An extended Cahn–Hilliard model (ECHM) was compared with the conventional phase-field model (CPFM) for simulating the operating state of a dendrite tip during the two-dimensional solidification of pure undercooled melts over a wide range of interfacial energy anisotropy. ECHM differs from CPFM in terms of how interfacial energy anisotropy is introduced. In ECHM, anisotropy comes solely from the anisotropic nature of the fourth-rank tensor terms included in free energy density, and not from assuming an orientation-dependent gradient energy coefficient <I>ɛ</I>(<I>θ</I>), which is the case in CPFM. ECHM resulted in dendrites growing with a rounded tip, even when anisotropy (<I>δ</I>) was greater than its critical value (<I>δ<SUB>c</SUB> </I>), but the tip radius at large anisotropy (<I>δ</I> ⩾ <I>δ<SUB>c</SUB> </I>) was limited by the interface width. In contrast to CPFM, ECHM did not engender an anomalous increase in the tip radius with bulk undercooling at small anisotropy (<I>δ</I> < <I>δ<SUB>c</SUB> </I>). In the simulation by ECHM, the tip velocity increased continuously with increasing <I>δ</I> beyond <I>δ<SUB>c</SUB> </I>. When compared in terms of the selection parameter <I>σ</I> <SUP>∗</SUP> of the dendrite tip, data obtained from ECHM fitted better to the <I>σ</I> <SUP>∗</SUP> ∝ <I>δ</I> <SUP>7/4</SUP> relationship over a wider range of <I>δ</I> than those obtained from CPFM. The present comparative study suggests that ECHM hinders the transition of the dendritic growth kinetics from diffusion-limited to interface-kinetic-limited, which occurs in the case of CPFM as the tip velocity increases with an increase in either undercooling or anisotropy.</P>