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천목 유약 및 소결 일정의 개발에 관한 연구 - 화천목 유약 편 -
정종혁 한국도자학회 2014 한국도자학연구 Vol.11 No.1
Nogime temmoku is a tea bowl which has crystal on the surface. It has brown pattern as like an ear of rice on the black background. Usually, this glaze of nogime temmmoku is used for tea bowl. For example, in case of Tenmoku produced in Japan, its plastic temperature is about 1290℃ and the time required for plasticity with the crystallization is about 35 hours, which result in high loss of time and economy. The purpose of this study is to identify how to solve this problem. That is, to reduce the plastic temperature to 1250〜1260℃ and the plasticization time to within 11〜12 hours as well as to simplify the schedule of plasticization. To achieve this purpose, development of new glaze should be conducted which is adequate in terms of plasticization time. In this study, the plasticization temperature has been fixed at 1250〜1260℃ to establish the composition and manufacturing procedure of the glaze from Tenmoku. 화천목이란 검은색 바탕에 갈색의 벼 이삭과 같은 침상 무늬가 결정으로 나타나는 다완을의미한다. 주로, 다완에 시유 된 유약이다. 현재 일본에서 생산되는 화목 천목의 예를 들면 소성온도는 약 1290℃에서 소성시간이 약35시간 이상 소요되어 화목천목의 결정이 아름답게는 만들어지나 시간과 경제성 면에서 손실이 크다. 본 연구의 목적은 이와 같은 문제점을 해결하고자 하는 것이다. 즉, 소성 온도를 1250〜1260℃로 낮추며 소성시간은 약 11〜12시간 이내로 단축시킴과 동시에 소성 스케줄도 간편하게 하려는데 그 목적이 있다. 이와 같은 연구목적을 달성하기 위해서는 소성시간에 맞는 새로운 유약개발이 함께 수행되어야 하므로 본 실험에서는 소성온도를 1250〜1260℃로 고정시켜 놓고 화목 천목 유약의 조성과 제조공정을 확립하고자 하였다.
고농도의 포도당이 치은섬유아세포 및 치주인대세포의 Prostaglandin $E_2$ 생성에 미치는 영향
정종혁,권영혁,이만섭,박준봉,허익,김성진,Chung, Jong-Hyuk,Kwon, Young-Hyuk,Lee, Man-Sup,Park, Joon-Bong,Herr, Yeek,Kim, Sung-Jin 대한치주과학회 1997 Journal of Periodontal & Implant Science Vol.27 No.4
The purpose of this study was to evaluate the effect of high glucose on prostaglandin E2 production in human gingival fibroblasts and periodontal ligament cells in vitro. In control group, the cells($5{\times}10^4\;cells/ml$) were cultured with Dulbecco's Modified Eagle's Medium contained with 10% fetal bovine serum, 45mg/dl glucose. In experimental groups, glucose was added to the above culture condition at the final glucose concentrations of 100mg/dl(Test group 1), 200mg/dl (Test group 2) and 400mg/dl (Test group 3). Then each group was tested for the cell proliferation rate, protein levels, and prostaglandin E2 production at $\frac{1}{2}$, 1, 2, 5 days. The results were as follows : 1. As glucose concentration increased, cell proliferation rate decreased significantly at 1, 2, 5 days in human gingival fibroblasts and periodontal ligament cells(P<0.01). 2. In human gingival fibroblasts, test group 2 and 3 showed significantly decreased protein levels as compared to control group at 5 days (P<0.01). 3. In human periodontal ligament cells, as glucose concentration increased, protein levels decreased significantly at 2 days and 5 days(P<0.01). 4. Prostaglandin $E_2$ production in human gingival fibroblasts and human periodontal ligament cells significantly increased as glucose concentration increased(P<0.01). results at 5 days showed obvious difference as compared to those at 2 days. From the above results, high glucose appeared to affect cellular activities including cell proliferation rate, protein levels and enhance prostaglandin $E_2$ production. It was assumed that prostaglandin E2 production by high glucose enhances inflammatory reaction and has a toxic effect on human gingival fibroblasts and human periodontal ligament cells. This study suggests that periodontal disease in diabetic patient is related to prostaglandin $E_2$ production.
Endovascular treatment for pseudoaneurysm after carotid blowout syndrome
정종혁,노영남,Lee Seo Hyeon,Jeong Yeong Seok,홍정호,손성일,박형종 대한신경집중치료학회 2020 대한신경집중치료학회지 Vol.13 No.2
Background: Pseudoaneurysms of the carotid artery are rare and can be both a cause and consequence of carotid blowout syndrome (CBS) in patients with head and neck cancer. Surgical or endovascular treatment approaches may be useful for managing this condition. Case Report: A 55-year-old man presented with a pulsatile mass surrounding the carotid bifurcation in the neck. He reported a history of CBS that occurred as a surgical complication while removing a benign neck cyst. Additionally, he reported a history of laryngeal cancer that underwent complete remission after surgery and radiotherapy. The mass was diagnosed as a pseudoaneurysm. Surgical treatment proved challenging owing to the patient’s history of neck surgery and radiotherapy; therefore, stent-graft deployment was performed and the absence of pulsations was checked through the neck mass. Conclusion: Endovascular treatment may be a useful therapeutic strategy in cases of post-CBS pseudoaneurysm in patients undergoing surgery and/or radiotherapy for head and neck cancer.
우수한 고조파 왜곡 특성을 가진 피드포워드 증폭기에 관한 연구
정종혁,강상욱,윤정오 경운대학교 산업기술연구소 2001 産業技術硏究論文誌 Vol.3 No.2(B)
Generally, the distortion of the negative feedback amplifier is reduced by a factor equal to the return difference (1 + β_1A_1), but the proposed feedforward amplifier is reduced by a factor equal to square of the return difference (1 + β_1A_1). In this paper, a feedforward amplifier with error correction is designed and implemented. So as to evaluate the characteristics of the harmonic distortion that the inverting feedforward amplifier is compared with that of the reference amplifier without feedforward error correction. It is confirmed that the proposed method should be able to improve much greater than compared with a conventional negative feedback amplifier. Therefore it should be noted that the proposed feedforward amplifier network is also acceptable for wide-band amplifiers and all of the network for the needless of harmonic distortion.
EDM 가공 공정에서 세장비 극대화를 위한 미세구멍의 최적가공 조건 결정
정종혁,이현욱,권원태 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-
Demand of micro holes has been increased fast, especially in the area of inkjet nozzle, micro turbine and optical parts. However, the micro hole with 40㎛ exit diameter and aspect ratio of 10 has yet to be reported. In this study, an endeavor was made to manufacture the micro hole under over 40㎛ exit diameter at stainless steel plate with 40㎛ thickness. To accomplish the goal, the relationship between machining parameters and machined result was identified. It was found that the entrance clearance was proportional to the discharge power, when discharge energy was kept constant and resistance had to be as high as possible at the given condition to minimize the machining time. 40㎛ average diameter of the micro hole with over 10 aspect ratio was achieved under the condition of 60V, 680pF, 500Ω, 1.5㎛ and 1500rpm.