• Title/Summary/Keyword: Choi Chang Hak

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Fabrication of Poly(diallyldimethylammonium chloride) - Patterned Substrates for Patterning of Single Strand DNA Using Ion Implantation

  • Ahn, Mi-Young;Hwang, In-Tae;Jung, Chan-Hee;Choi, Jae-Hak;Nho, Young-Chang
    • Journal of Radiation Industry
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    • v.5 no.3
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    • pp.243-247
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    • 2011
  • In this study, a convenient method for the selective immobilization of single strand DNA (ssDNA) on a polymer surface was described. A positively charged polyelectrolyte, poly(diallyldimethylammonium chloride) (PDDA), was spin-coated on a tissue culture petridish and the micropatterns of the PDDA were formed by selective ion implantation through a pattern mask. The surface property of the implanted PDDA was investigated by using a surface profiler and FT-IR spectrometer. Cy3-labeled ssDNA was selectively immobilized on the PDDA patterns through ionic interaction and thus, well-defined ssDNA patterns were obtained.

Interfacial Stress Concentrations of Vertical Through-plate to H-beam Connections in CFT Column

  • Choi, Insub;Chang, HakJong;Kim, JunHee
    • International Journal of High-Rise Buildings
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    • v.9 no.4
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    • pp.325-334
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    • 2020
  • This paper aims to evaluate the interfacial stress concentrations on connection between vertical through-plate and H-beam in CFT column. Full-scale experiments were performed on three specimens with varying thickness of the vertical through-plate to investigate the interfacial stress concentration factor in the connections. The specimens underwent brittle failure at the location where the steel beam is connected to the vertical through-plate before the steel beam reached its plastic moment. The strain data of the part were analyzed, and the sectional analyses were conducted to determine appropriate residual stress models. In addition, the stress concentration factor was quantified by comparing the analytical local behavior in which the stress concentration is not reflected and the experimental data reflecting the stress concentration. The results showed that the maximum reduction of the stress concentration factor due to an increase in the thickness of the vertical through-plate is 50.3%.

Thermally Crosslinked Polyimide Binders for Si-alloy Anodes in Li-ion Batteries

  • Chang, Hyeong-Seok;Ji, Sang-Gu;Rho, Miso;Lee, Byoung-Min;Kim, Sung-Soo;Choi, Jae-Hak
    • Journal of Electrochemical Science and Technology
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    • v.13 no.3
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    • pp.339-346
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    • 2022
  • Silicon (Si) has attracted considerable attention due to its high theoretical capacity compared to conventional graphite anode materials. However, Si-based anode materials suffer from rapid capacity loss due to mechanical failure caused by large volume change during cycling. To alleviate this phenomenon, crosslinked polymeric binders with strong interactions are highly desirable to ensure the electrode integrity. In this study, thermally crosslinked polyimide binders were used for Si-alloy anodes in Li-ion batteries. The crosslinked polyimide binder was found to have high adhesion strength, resulting in enhanced electrode integrity during cycling. Therefore, the Si-alloy anodes with crosslinked polyimide binder provide enhanced electrochemical performance, such as Coulombic efficiency, capacity retention, and cycle stability.

Experimental Study of Flow and Solidification Simulation for Thin Wall Stainless Steel Castings (박육 스테인리스 주강에 대한 유동 및 응고해석의 실험적 고찰)

  • Choi, Hak-Kyu;Park, Heung-Il;Jeong, Hae-Yong;Bae, Cha-Hurn;Choi, Byung-Kang
    • Journal of Korea Foundry Society
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    • v.20 no.5
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    • pp.344-353
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    • 2000
  • In order to find out the casting conditions of the thin wall stainless steel exhaust manifold for automobile, the melt flow and solidification behavior simulated by the Z-CAST program were evaluated, and experimental casting result on the test casting and exhaust manifold of SSC13 alloy were investigated. From the results of this study, it was shown that the calculated results on fluid flow were in good agreement with practical thin wall test castings under the same casting conditions, as pouring metal is austenitic stainless steel(SSC13) and pouring temperature is 1575, 1630, and $1665^{\circ}C$ respectively. That calculated result with designed thin wall exhaust manifold was predicted filling up into the mold cavity, and practical casting was sound. The solidification simulation was predicted shrinkages at the bosses for original exhaust manifold, and designed it without bosses was predicted no defect. Therefore practical exhaust manifold casting was sound and in good agreement with calculated solidification results.

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Epithelial-Myoepithelial Carcinoma of the Salivary Gland: Review of the Literature with Report of Four Cases (타액선에 발생한 상피-근상피암 4예)

  • Choi Dong-Jin;Suh Jin-Hak;Cheoug Woung-Youn;Choi Eun-Chang;Kim Hyeong-Joon;Kang Hae-Youn;Park Cheong-Soo
    • Korean Journal of Head & Neck Oncology
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    • v.17 no.2
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    • pp.238-241
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    • 2001
  • Epithelial-myoepithelial carcinoma is a rare neoplasm comprising approximately 1% of all salivary gland neoplasms. Histopathologically, the carcinomas are characterized by a dual cell population of an inner duct-forming epithelium and an outer myoepithelial cell. They are characterized by their variable clinical course and a lack of features that predict clinical outcome. The following report describes our experience with this type of tumor. We suggest that radiation therapy and long term follow-up will be necessary because this tumor have a high risk of locoregional aggressiveness.

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The Effect of Rolling on the Charge-Discharge Characteristic of Metal Hydride Electrode for Ni-MH Secondary Battery (압연이 Ni-MH 2차전지용 금속수소화물 전극의 충·방전 특성에 미치는 영향)

  • Park, Won;Chang, Sang-Min;Choi, Seung-Jun;Noh, Hak;Choi, Jeon;Park, Choong-Nyeon
    • Journal of Hydrogen and New Energy
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    • v.7 no.2
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    • pp.165-171
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    • 1996
  • The effect of rolling on the charge-discharge property was studied for metal hydride negative electrode. $(LM)Ni_{3.6}Al_{0.4}Co_{0.7}Mn_{0.3}$(pleateau pressure : below 1 atm at room temperature, volume expansion : 9%, entalpy : $8.7kcal/molH_2$) alloy was prepared by arc melting, and then it was coated with various copper weight percent. The copper coated alloys were then rolled with the different reduction ratio. From the results, it was found that the maximum discharge capacity increased with increasing reduction ratio, and 15wt% copper coated sample shows the highest discharge capacity, 324mAh/g, after rolling with 30% reduction ratio. In view of cycle life for the negative electrode, the 15wt% copper coated electrode which was rolled with 13% reduction ratio showed the longest cycle life compared with other electrodes.

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Primary Malignant Fibrous Histiocytoma of the Pleura

  • Cho, Kyung-Hwa;Park, Chul;Hwang, Ki-Eun;Hwang, Yu-Ri;Seol, Chang-Hwan;Choi, Keum-Ha;Lee, Mi-Kyung;Choi, Soon-Ho;Kim, Hak-Ryul;Jeong, Eun-Taik
    • Tuberculosis and Respiratory Diseases
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    • v.74 no.5
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    • pp.222-225
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    • 2013
  • Malignant fibrous histiocytoma, a type of sarcoma, is a malignant neoplasm with uncertain origin that arises in both the soft tissues and the bone. The occurrence of primary malignant fibrous histiocytoma of the pleura is extremely rare. We report a case of a 65-year-old Korean man who is being diagnosed with primary malignant fibrous histiocytoma of the pleura.

Dyeability of Poly(trimethylene terephthalate) Fiber Annealed by Passing on the Plate Heater (연속순간 평판 열처리에 의한 폴리(트리메틸렌 테레프탈레이트) 섬유의 염색성)

  • Hong, Sung-Hak;Choi, Chang-Nam;Choi, Hee;Song, Min-Kyu;Kim, Yong
    • Textile Coloration and Finishing
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    • v.15 no.2
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    • pp.59-67
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    • 2003
  • PTT[poly(trimethylene terephthalate)] fiber was annealed by passing on the plate heater to illuminate the effects of annealing on the mechanical properties and dyeability with varying the treatment temperature for 0.5 second. The apparent crystal sizes and crystallinity were increased with increases in temperature. With the increases of the temperature, the dynamic viscoelastic behaviors were analyzed to be reduction in $T_{max} (tan{\delta})$. The initial modulus were observed to be a small enhanced. The shrinkage in hot water were reduced. The dyeability for disperse dye enhanced dramatically, for example, a satisfactory degree of exhaustion was obtained by dyeing at $95^\circ{C}$ for 30 min with the PTT fibers heat treated at $180^\circ{C}$.

천연염색된 멜란지 얀의 제조와 그의 항균ㆍ소취성

  • Choi, Hee;Shin, Yoon-Sook;Hong, Sung-Hak;Choi, Chang-Nam;Kim, Sang-Ryul
    • Textile Coloration and Finishing
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    • v.16 no.2
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    • pp.25-33
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    • 2004
  • Melange yams were prepared by varing the ratio of raw cotton dyed with Indigo, Gardenia and Sappan wood colorants, respectively. The antibacterial activity and deodorization on melange yarns were evaluated for bacteria reduction rate and deodorization rate. The bacterial reduction rate on melange yarns was explored with Staphylococcus aureus, Klebsiella pneumoniae. The melange yarns on the ratio of raw cotton dyed with Sappan wood and Indigo showed high Staphylococcus aureus reduction rate of 99% and 90%, regardless of Al-mordanting treatment, but those with Gadenia hardly showed bacteria reduction rate. The melange yarn showed high Klebsiella pneumoniae reduction rate of 99% for Al-mordanting treatment with Sappan wood. The others were poor. The deodorization of 81% and 98∼99% obtained with melange raw sliver and melange sliver dyed with Indigo, Gardenia and Sappan wood colorants, but dyeing did not significantly affect deodorization rate.

Preoperative Evaluation and Significance of Carotid Resection in Advanced Cervical Metastatic Cancer (진행된 경부 전이암에서 경동맥 절제를 위한 술전검사와 절제술의 의의)

  • Cho Jung-Il;Kim Young-Mo;Choi Won-Suk;Choi Sang-Hak;Han Chang-Joon
    • Korean Journal of Head & Neck Oncology
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    • v.17 no.1
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    • pp.13-18
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    • 2001
  • Objectives: We studied what is the role of elective carotid artery resection in the management of advanced cervical metastatic cancer. Materials and Methods: 5 patients with elective carotid artery resection in advanced metastatic cervical cancer were reviewed retrospectively. The patients underwent complete neuroradiologic evaluation, including CT/MRI. angiography, duplex doppler, balloon occlusion test with EEG, and brain SPECT for determination of compatible collateral circulation after carotid artery resection. Results: Perioperative complication were appeared in 2 patients those were middle cerebral arterial infarction and mediastinal bleeding. Postoperative mortality rate was 20%. 4 patients recurred within 1 year. Conclusion: Preoperative collateral study rarely provide whether resection carotid artery or not. Elective carotid artery resection cannot provide locoregional control of tumor and don't promote survival.

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