• Title/Summary/Keyword: Choi Chang Hak

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Expressed Sequence Tags of Trichinella spiralis Muscle Stage Larvae

  • Park, Hae-Kyung;Chang, Seong-Won;Kang, Se-Won;Cho, Min-Kyoung;Choi, Sun-Hee;Hong, Yeon-Chul;Lee, Yong-Seok;Jeong, Hae-Jin;Yu, Hak-Sun
    • Parasites, Hosts and Diseases
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    • v.46 no.2
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    • pp.59-63
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    • 2008
  • In order to obtain greater insight into the relevant genomic expression patterns of Trichinella spiralis, 992 expressed sequence tags (ESTs) were collected from a cDNA library of T. spiralis muscle stage larvae and assembled into 60 clusters and 385 singletons. Of them, 445 (44.7%) ESTs were annotated to their homologous genes, and small fractions were matched to known genes of nematodes. The annotated ESTs were classified into 25 eukaryotic orthologous groups (KOG). Cytochrome C oxidase (34 clones) was found to be most frequent species.

Endoscopic Chemocauterization for Pyriform Sinus Fistula (이상와루(Pyriform Sinus Fistula)에 대한 내시경적 경화요법의 3예)

  • Park Yoon-Ah;Seo Jin-Hak;Cho Sang-Hyun;Chung Woong-Yoon;Choi Eun-Chang;Park Cheong-Soo
    • Korean Journal of Head & Neck Oncology
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    • v.17 no.2
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    • pp.234-237
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    • 2001
  • Pyriform sinus fistula is a rare anomaly arising from 3rd or 4th branchial apparatus and has been recognized as one cause of acute suppurative thyroiditis or acute deep neck infection. Pyriform sinus fistula must be considered when a clinician is encountered recurrent left lower neck abscess and a history of repeated incision and drainage. The confirmation of the diagnosis is made when the fistula tract is identified on a barium swallow study and when the internal orifice of the fistula is found at the apex of pyriform sinus on laryngoscopic examination. A complete excision of the fistula tract has been proposed as a treatment of choice. However, in some cases it is very difficult to resect the tract completely because of severe inflammation and repeated drainage procedure. We present three cases of pyriform sinus fistula which are successfully treated by laryngomicroscopic chemocauterization using synthetic fibrin and $AgNO_3$.

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Development of Vibration Assisted Hybrid Femtosecond Laser Ultra-precision Machining System and Cu-Zn alloy Application (진동자를 이용한 하이브리드 극초단 펄스 레이저 초정밀가공시스템 개발 및 Cu-Zn합금 응용)

  • Choi, Won-Suk;Yoon, Ji-Wook;Cho, Sung-Hak;Kang, Myung-Chang
    • Journal of Powder Materials
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    • v.20 no.4
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    • pp.308-312
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    • 2013
  • In this paper, we describe experiment results using a vibration assisted hybrid femtosecond laser (${\lambda}$:795 nm) ultra-precision machining system. The hybrid system we have developed is possible that optical focal point of the femtosecond laser constantly and frequently within the range of PZT(piezoactuator) vibrator working distance. Using the hybrid system, We have experimented on brass and studied about differences of result of hole aspect ratio compare to general experiment setup of femtosecond laser system. Aspect ratio of a micro hole on brass is increased as 54% with 100 Hz vibration frequency and surface roughness of the side wall also improved compare to non-vibration.

Preparation of Son Exchange Kapok Fiber by Radiation Polymerization (방사선 중합법에 의한 Kapok 이온교환 섬유의 합성)

  • Cho, In-Hee;Kang, Phil-Hyun;Lim, Youn-Mook;Choi, Jae-Hak;Hwang, Taek-Sung;Nho, Young-Chang
    • Polymer(Korea)
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    • v.31 no.6
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    • pp.512-517
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    • 2007
  • The grafting of styrene, glycidylmethacrylate (GMA) or acrylic acid (AAc) onto kapok fiber were performed by $Co_{60}\;{\gamma}-ray$ radiation-induced graft copolymerization. Degree of grafting (DG) of copolymers were increased with increasing monomer concentration and radiation dose. In addition to we confirmed the introduced functional group and measured ion exchange capacity. Morphology of the ion exchange fibers and their structures were analyzed by SEM and FT-IR.

Midfacial distraction osteogenesis of Crouzon syndrome with RED(Rigid External Distraction) system (RED(Rigid External Distraction) system을 이용한 Crouzon syndrome환자의 distraction osteogenesis)

  • Lee, Yang-Ku;Choi, Jeong-Ho;Kim, Seok-Hwa;Baek, Seung-Hak;Chang, Young-Il
    • The korean journal of orthodontics
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    • v.32 no.3 s.92
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    • pp.175-183
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    • 2002
  • Crouzon syndrome Is one of the craniofacial syndromes characterized by craniosynostosis, midfacial hypolpasia and ocular proptosis. Distraction osteogenesis is becoming Important technique to treat craniofacial dyplaisa. It has nuy advantages compared with standard orthognathic surgery. Maxillary distraction osteogenesis after Le Fort III osteotomy with the RED system presents successful maxillary protraction to Crouzon syndrome patient with severe maxillary deficiency. It also allows remarkable improvement of facial esthetics and respiratory functions.

Adsorption Kinetic and Isotherm Characteristics of Mn Ions with Zeolitic Materials Synthesized from Industrial Solid Waste (산업폐기물로부터 합성된 제올라이트 물질의 망간 이온 흡착속도 및 등온흡착 특성)

  • Choi, Jeong-Hak;Lee, Chang-Han
    • Journal of Environmental Science International
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    • v.29 no.8
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    • pp.827-835
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    • 2020
  • Zeolite material having XRD peaks of Na-A zeolite in the 2θ range of 7.18 to 34.18 can be synthesized from the waste catalyst using a fusion/hydrothermal method. The adsorption rate of Mn ions by a commercial Na-A zeolite and the synthesized zeolitic material increased as the adsorption temperature increased in the range of 10 ~ 40℃. The adsorption of Mn ion were very rapid in the first 30 min and then reached to the equilibrium state after approximately 60 min. The adsorption kinetics of Mn ions by the commercial Na-A zeolite and the zeolitic material were found to be well fitted to the pseudo-2nd order kinetic model. Equilibrium data by the commercial Na-A zeolite and the zeolitic material fit the Langmuir, Koble-Corrigan, and Redlich-Peterson isotherm models well rather than Freundlich isotherm model. The removal capacity of the Mn ions by the commercial Na-A zeolite and the zeolitic material obtained from the Langmuir model was 135.2 mg/g and 128.9 mg/g at 30℃, respectively. The adsorption capacity of Mn ions by the synthesized zeolitic material was almost similar to that of commercial Na-A zeolite. The synthesized zeolitic material could be applied as an economically feasible commercial adsorbent.

Integrated Gate Driver Circuit Using a-Si TFT with AC-Driven Dual Pull-down Structure

  • Jang, Yong-Ho;Yoon, Soo-Young;Kim, Binn;Chun, Min-Doo;Cho, Hyung-Nyuck;Cho, Nam-Wook;Sohn, Choong-Yong;Jo, Sung-Hak;Choi, Seung-Chan;Kim, Chang-Dong;Chung, In-Jae
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.944-947
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    • 2005
  • Highly stable gate driver circuit using a-Si TFT has been developed. The circuit has dual-pull down structure, in which bias stress to the TFTs is relieved by alternating applied voltage. The circuit has been successfully integrated in 4-in. QVGA and 14-in. XGA TFT-LCD with a normal a-Si process, which are stable for over 2,000 hours at $60^{\circ}C$. The enhancement of stability of the circuit is attributed to retarded degradation of pull-down TFTs by AC driving.

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Estimation of Dynamic Stiffness of a Rubber Bush (고무부품의 동특성 예측)

  • Goo, Jun-Hwan;Ahn, Tae-Kil;Kim, Joo-Sung;Lee, Yong-Heon;Bae, Dae-Sung;Kim, Kee-Joo;Choi, Byung-Ik;Lee, Hak-Joo;Woo, Chang-Su;Kim, Kyung-Shik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.11
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    • pp.1244-1248
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    • 2009
  • Although rubber components are extensively used in mechanic parts. There are still a lot of difficulties in designing the rubber components applied in complex shapes and preloaded states because of the complicated material properties. One of the most important parameters for more detailed and accurate mechanical analysis during the development stages is the dynamic characteristics of the rubber components. It is well known that the dynamic properties of rubber are dependent on frequency as well as static preload. Consequently, a large number of experiments have to be conducted to identify the dynamic stiffness of a rubber bush considering the various applied conditions. In this paper, an efficient experimental method is suggested, which estimates the dynamic stiffness of a rubber bush using rubber material test and static stiffness of the bush. This method is capable of predicting the dynamic stiffness of a rubber bush under various load conditions from minimized test data.

The Efficacy and Safety of Platelet-Rich Plasma and Adipose-Derived Stem Cells: An Update

  • Choi, Jaehoon;Minn, Kyung Won;Chang, Hak
    • Archives of Plastic Surgery
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    • v.39 no.6
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    • pp.585-592
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    • 2012
  • During the past decade, many studies using platelet-rich plasma (PRP) or adipose-derived stem cells (ASCs) have been conducted in various medical fields, from cardiovascular research to applications for corneal diseases. Nonetheless, there are several limitations of practical applications of PRP and ASCs. Most reports of PRP are anecdotal and few include controls to determine the specific role of PRP. There is little consensus regarding PRP production and characterization. Some have reported the development of an antibody to bovine thrombin, which was the initiator of platelet activation. In the case of ASCs, good manufacturing practices are needed for the production of clinical-grade human stem cells, and in vitro expansion of ASCs requires approval of the Korea Food and Drug Administration, such that considerable expense and time are required. Additionally, some have reported that ASCs could have a potential risk of transformation to malignant cells. Therefore, the authors tried to investigate the latest research on the efficacy and safety of PRP and ASCs and report on the current state and regulation of these stem cell-based therapies.

A Survey on Quality of Radiographs in Frontal Projection of the Chest (흉부(胸部) 정면(正面)X선사진(線寫眞)의 화질(畵質)에 관한 검사(檢討))

  • Choi, Jong-Hak;Jeon, Man-Jin;Lee, Chang-Yup
    • Journal of radiological science and technology
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    • v.8 no.2
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    • pp.11-14
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    • 1985
  • The author came to analize and get the following problems after researched radiographic quality in order to find out the necessary factors to improve in radiographs of frontal projection of the chest selected at random of the adult patients (1545 male, 1520 female) who had been examined in 4 departments of radiology of the general hospitals in Seoul and Kyungki area. 1. Problems of x-ray film or of radiographic cassette appeared in 2.97% radiographs on account of selection of the film size (except costophrenic sinus) (1.79%), poor screen-film contact (0.85%), light leakage of cassette (0,33%). 2. Problems of patients' positioning or breathing appeared in 16.57% radiographs of all because of overlapping of lung apex and clavicle (6.98%), overlapping of scapula and lung field (5.87%), asymmetrical projection of clavicles (1.76%), errors in positioning and breathing of the patient (1.96%). 3. Problems of x-ray exposure factors or film processing appeared in 22.25% radiographs because of over-density (2.64%), under-density (3.95%), fog (0.59%), demonstration density under clavicles or lung marking unsharply (3.82%), not clear of lung marking from breast region (0.94%), not clear the lung marking from the part overlapped of heart and lungs (3.92%), not clear the lung marking from the part overlapped of liver and lung (6.49%).

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