• Smart Structures and Systems
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• 제18권4호
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• pp.643-662
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• 2016

The monitoring of structural integrity of pipeline tapered thread connections is of great significance in terms of safe operation in the industry. In order to detect effectively the loosening degree of tapered thread connection, an active sensing method using piezoceramic transducers was developed based on time reversal technique in this paper. As the piezoeramic transducers can be either as actuators or sensors to generate or detect stress waves, the energy transmission for tapered thread connection was analyzed. Subsequently, the detection principle for tapered thread connection based on time reversal was introduced. Finally, the inherent relationship between the contact area and tightness degree of tapered thread connection for the pipe structural model was investigated. Seven different contact area scenarios were tested. Each scenario was created by loosening connectors ranging from 3 turns to 4.5 turns in the right tapered threads when the contact area in the left tapered threads were 4.5 turns. The experiments were separately conducted with a highly noisy environment and various excitation signal amplitudes. The results show the focused peaks based on time reversal have the monotonously rising trend with the increase of the contact areas of tapered threads within an acceptable monitoring resolution for metal pipes. Compared with the energy method, the proposed time reversal based method to monitor tapered threads loosening demonstrates to be more robust in rejecting noise in Structural Health Monitoring (SHM) applications.

• 대한기계학회논문집A
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• 제40권11호
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• pp.971-978
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• 2016

최근 전자제품의 소형화 및 경량화 추세에 따라 초소형 체결제품의 개발 필요성이 대두되고 있다. 본 연구에서는 이동통신기기 적용을 위한 초소형 나사(외경 1.0 mm 피치 0.25 mm)의 전조공정에 대한 연구를 수행하였으며, 특히 대칭 나사산과 비대칭 나사산의 성형을 위한 전조공정의 유한요소해석을 수행하였다. 유한요소해석을 통해 전조금형의 수평방향 간격, 수직방향 간격, 이동 거리 등의 공정변수가 성형된 나사산의 형상정밀도에 미치는 영향을 분석하였다. 또한 대칭 나사산과 비대칭 나사산에서 발생되는 재료 유동의 차이를 비교하고, 그에 따른 공정변수의 영향을 분석하였다. 상기 해석 결과로부터 도출된 공정변수를 실제 전조공정에 적용한 결과 대칭 나사산과 비대칭 나사산 모두 원하는 형상정밀도 내에서 성공적으로 성형될 수 있음을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1443-1445
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• 1997

This paper presents an analysing method to find out an optimum metal shape for insulation strength of SCI(Silicone Composite Insulator). Using finite element method, the interested parameters of the configuration such as a aspect of metal/silicone composite and a material properties are investigated and derived a thread of optimum design parameters.

• Elastomers and Composites
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• 제44권4호
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• pp.391-396
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• 2009

본 연구에서는 전조공정의 수치해석을 수행하였다. 해석을 이용한 공정 인자 설계에 앞서서, 효율적이고 신뢰성 있는 해석을 위한 해석 조건에 대하여 연구를 수행하였다. 치형의 개수와 요소의 수에 대한 해석 결과를 바탕으로 해석의 정도를 보장하고 효율적으로 해석을 수행할 수 있는 조건을 설정하였다. 그리고, 프랭크 각도와 치형의 끝단부 라운드 등의 금형의 형상과 성형 온도가 유효 응력, 유효 변형율, 전조력, 그리고 크랙 발생에 미치는 영향을 알아보았다. 해석은 DEFORM-3D를 이용하여 수행하였다. 프랭크 각도와 치형의 끝단 부 라운드는 전조력에 영향을 미치는 것을 확인할 수 있었으며, 성형 온도 조건에 따라서 유효 변형률과 전조력, 그리고 크랙을 예상 할 수 있었다.

• Archives of Plastic Surgery
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• 제50권3호
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• pp.248-253
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• 2023

Metal fixation systems for cranial bone flaps cut by a drill are convenient devices for cranioplasty, but cause several complications. We use modified craniotomy using a fine diamond-coated threadwire saw (diamond T-saw) to reduce the bone defect, and osteoplasty calcium phosphate cement without metal fixation. We report our outcomes and tips of this method. A total of 78 consecutive patients underwent elective frontotemporal craniotomy for clipping of unruptured intracranial aneurysms between 2015 and 2019. The follow-up periods ranged from 13 to 66 months. The bone fixation state was evaluated by bone computed tomography (CT) and three-dimensional CT (3D-CT). The diamond T-saw could minimize the bone defect. Only one wound infection occurred within 1 week postoperatively, and no late infection. No pain, palpable/cosmetically noticeable displacement of the bone flap, fluid accumulations, or other complications were observed. The condition of bone fixation and the cosmetic efficacy were thoroughly satisfactory for all patients, and bone CT and 3D-CT demonstrated that good bone fusion. No complication typical of metal fixation occurred. Our method is technically easy and safety, and achieved good mid-term bone flap fixation in the mid-term course, so has potential for bone fixation without the use of metal plates.

• 복식
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• 제45권
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• pp.161-178
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• 1999

In contemporary fashion metal have used which is as the material with a sufficient potentiality of expression which is displayed by an unique characteristic involved only in metal. In this paper metal expressed in contemporary fashion is researched. The first thing the formative characteristic of metal is researched under the consideration of type technique and color of metal used in contemporary fashion. Metals such as gold silver bronze aluminum thin lead and iron are usually used in fashion and those metals are used in various types such a thread fabric board leaf a and cable. Those types of metal as above are applied to the clothing by the techniques of weaving embroidering metal leaf printing or moulding which gives the formative characteristic to the clothing. In color metal has an effect on the colors of surroundings by its smooth and unique luster and its effect of reflection and produces the visual formative characteristic through the effects of contrast. The esthetic will of metal expressed in modern fashion is researched in this study under the facts studied as above. first metal expresses the future oriented esthetic Second metal has the characteristic of attracting the attention Third metal is used as valid techniques to express the artistic formation for clothing escaping from the idea that the clothing is only for wearing. Finally metal is used as an anti-cultural tool of fighting against the existing order or spirit.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.125.2-125.2
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• 2005

• 한국군사과학기술학회지
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• 제13권5호
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• pp.769-774
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• 2010

It happened fractures on special bolt which supported main landing gear actuator up-lock rod of aircraft. Cracks were initiated mainly from the center hole and the external thread of the special bolt. To find out failure root causes, metallographic, fractographic analyses as well as test work were carried out. From the fractographic study by SEM work, fracture occurred by a brittle intergranular type failure. The fracture could be occurred primarily by solid-metal-induced embrittlement due to cadmium embrittler penetrated into the flaw existed after machining work for center hole and thread on the bolt during baking treatment processing to eliminate hydrogen. For its successful application, cadmium EP bolts require proper and adequate baking treatment after electroplating, and make no more drilled center hole on the bolt to prevent same failure.

• 보존과학회지
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• 제38권2호
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• pp.124-132
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• 2022

본 연구는 국가민속문화재 일월수 다라니 주머니 매듭과 테두리 장식에 사용된 '금속 장식지'를 대상으로 과학적 분석을 통해 재료적 특성을 파악하였다. 금속 장식지는 SEM-EDS 분석을 통해 은(Ag) 및 황(S)이 확인되어 은제 금속박을 배지에 부착하여 제작한 것으로 추정할 수 있다. 황(S)은 농도와 접촉시간에 따라 은(Ag)을 황색부터 흑색까지 변색시킬 수 있다. 현재는 황색을 확인할 수 없으나, 은(Ag)으로 가금사를 만든 사례가 있어 본래 색을 추정하기 위해서는 추가 연구가 필요하다. 배지는 배면까지 적갈색이다. 함께 검출된 알루미늄(Al)과 규소(Si), 철(Fe)은 전통 편금사(片金絲)의 붉은색 접착제로 추정되는 주토(朱土)의 주성분으로, 금속 장식지의 접착제 관련 성분으로 추측된다. GC/MS 분석 결과에서 접착제 성분은 아교(阿膠)로 확인할 수 있었다.

• 복식
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• 제58권5호
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• pp.198-210
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• 2008

The purpose of this study is to establish the conservation methods of embroidered textiles and textile works. The conservation of remained textiles is consisting of examination, cleaning, support and consolidation, restoration, and storage and display process. It aims to prevent the damage on textile remains for long time display and storage and to prolong their aesthetics and functionality. The embroidered textiles and textiles works, which are remained by handed down or excavated or included in the Buddhist are embossed with colorful threads on the fabrics: the stitches include embroideries on clothing, bed clothes, wrapping clothes, utensil pouches, panels and Buddhist goods; textile works include hats, ornaments, shoes, attachments of clothes etc. These are composed of mainly fabrics, precious metals, leathers and precious stones, etc., and are fabricated by several techniques such as braiding, twining, sewing as well as weaving. Metal threads were also used to add a decorative effect on these goods. In order to conserve and preserve the remained goods, a special care must be taken on the metal threads, which are the most fragile material among the constituents. Hence, characteristics of metal threads and its cleaning methods, general conservation techniques of a rank badge, which is brocaded and partly attached to Cheogori and Samo(men's hat) from the excavated old tombs are introduced here.