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바인더 젯 3D 프린터의 프린팅 헤드 내구성 향상을 위한 연구
황정철,김태성 대한안전경영과학회 2023 대한안전경영과학회지 Vol.25 No.2
This research was conducted to reduce the defect rate caused by nozzle clogging of printing heads used in binder jet 3D printers. The binder jet 3D printing technology may adhere to the printing head nozzle by dispersing powder due to mechanical operation such as transferring the printing head and supplying powder, and may cause nozzle clogging by natural curing at the nozzle end depending on the type of binder used. To solve this problem, this study created a cleaning module exclusively for printing heads to check whether the durability of printing heads is improved through analysis of printing results before and after using the cleaning module. To this end, this research used a thermal bubble jet printing head, and the used powder was studied using gypsum powder.
동측 역행성 유경 피판술을 이용한 무지의 재건 - 1예 보고 -
황정철,정덕환,Hwang, Jung-Chul,Chung, Duke-Whan 대한미세수술학회 2011 Archives of reconstructive microsurgery Vol.20 No.1
Reconstruction of the distal portion of the great toe has always represented a difficult problem to surgeons. There are many methods of flap reconstruction described for foot defects, but none for tip of the great toe. We report a case of reconstruction of the great toe using a homodigital reverse pedicle island flap method. A 25-year-old man had a crushing injury at the distal phalanx of the left great toe. A homodigital reverse pedicle island flap was raised from the dorso-medial aspect of the proximal phalanx of the great toe based on the distal dorsal arcade. The flap covered the exposed distal phalanx and stump was closed without shortening. He made an uncomplicated recovery and when seen 6 months later he had a good cosmetic and functional result. A homodigital reverse pedicle island flap is described for the reconstruction of the distal part of the great toe. It involves only a single stage procedure with minimal donor site morbidity and provides a good cosmetic results.
유리 피판술과 동측 혈관 부착 비골 전위술을 이용한 경골 결손의 재건
황정철,정덕환,한정수,이재훈,고택수,박양우,박진성,Hwang, Jung-Chul,Chung, Duke-Whan,Han, Chung-Soo,Lee, Jae-Hoon,Ko, Taeg-Su,Park, Yang-Woo,Park, Jin-Sung 대한미세수술학회 2008 Archives of reconstructive microsurgery Vol.17 No.2
Segmental defects of the tibia after open fractures, sepsis and a tumor surgery are among the most difficult and challenging clinical problems. Tibia defects in these situations are complicated with infection and are resistant to conventional bone grafting techniques. The aim of this study is to report the results and discuss the role of free flap followed by ipsilateral vascularized fibular transposition (IVFT) for reconstruction of tibia defects. Ten patients had free flap followed by IVFT in the period 1989~2007. Mean age was 25.3 years. The patients were followed for an average of 3.4 years. All flaps were survived including 1 case with venous thrombosis requiring additional surgery. The average time to union of proximal and distal end was 5.2 months, 8.2 months, each other. All transposed fibula were viable at last follow-up. IVFT offers the advantages of a vascularized graft. In patients with large bone and soft tissue defects combined with infection, free flap followed by IVFT is an useful and reliable method without microvascular anastomosis.
사형 주조에서 바인더 젯 3D 프린터를 이용한 기계적 물성 향상을 위한 공정 연구
황정철,김태성 대한안전경영과학회 2023 대한안전경영과학회지 Vol.25 No.1
Among the Additive Manufacturing (AM) technologies, the Binder-Jetting printing technology is a method of spraying an adhesive on the surface of powder and laminate layer by layer. Recently, this technique has become a major issue in the production of large casting products such as ship-building, custom vehicles and so on. In this study, we performed research to make actual mold castings and increase mechanical property by using special sand and water-based binders. For use as a mold, it has a strength of more than 3MPa and permeability. Various experiments were carried out to obtain suitable them. The major process parameters were binder jetting volume, binder types, layer thickness and heat treatment condition. As a result of this study, the binder drop quantity was measured to be about 60 pico-liter, layer thickness was 100μm and the heat treatment condition was measured about 1,000℃ and compressive strength were measured to be more than 5MPa. The optimum condition of this experiment was established through actual casting of aluminum. The equipment used in this study was a Freeforms T400 model (SFS Co., Ltd.), and the printing area of 420 * 300 * 250mm and resolution of 600dpi can be realized.
유도 선수에서 발생한 수지 근위 지관절의 재발성 전방 회전 탈구 - 1례 보고 -
황정철,정덕환,한정수,Hwang, Jung-Chul,Chung, Duke-Whan,Han, Chung-Soo 대한정형외과스포츠의학회 2009 대한정형외과스포츠의학회지 Vol.8 No.1
수지 근위 지관절의 전방 회전 탈구는 매우 드물게 발생한다. 저자들은 여자 유도 선수에서 발생한 수지 근위 지관절의 전방회전 탈구를 경험하였기에 이를 문헌고찰과 함께 보고하고자 한다. 24세 여자 유도 선수로 총 4번의 근위 지관절 전방 탈구가 발생하였다. 수술 시 회전 손상으로 파열된 척측 측부 인대와 파열 없이 늘어져 있는 중앙 건을 확인할 수 있었다. 수술적 치료로 파열된 척측 측부 인대 봉합술과 중앙 건과 측부대 사이를 봉합하여 근위 지관절의 배측부를 강화 시켜주었다. 술 후 운동시에 탈구는 다시 발생하지 않았다. 수지 근위 지관절의 전방 회전 탈구는 매우 드문 손상이지만 다른 탈구처럼 조기 진단과 치료, 그리고 단계적인 재활이 무엇보다 중요하겠다. Volar rotatory dislocation of the proximal interphalangeal joint(PIP) of the finger is rare. We report a female judo player who had volar rotatory dislocation of the PIP joint of the middle finger. She had dislocation of PIP joint total 4 times. At operation, the central tendon was identified as being distension, with the ulnar collateral ligament ruptured. The ruptured ulnar collateral ligament was interposed within the joint. The ruptured ulnar collateral ligament was repaired and extensor expansion was repaired. At last follow-up, she didn't have recurrent dislocation during judo. Accurate diagnosis, early intervention and progressive rehabilitation of this injury are very important as other dislocations.
요골 원위부 골절 후 발생한 급성 장무지 신전건 파열 -1예 보고-
황정철,정덕환,Hwang, Jung Chul,Chung, Duke Whan 대한정형외과초음파학회 2011 대한정형외과 초음파학회지 Vol.4 No.1
원위부 요골 골절의 합병증 중 하나인 장무지 신전건 파열은 지연성으로 발생한다고 알려져 있다. 요골 골절과 동시에 발생하는 급성 장무지 신전건 파열은 매우 드문 경우로, 저자들은 문헌 고찰과 함께 증례 보고 하고자 한다. Late rupture of the extensor pollicis longus (EPL) tendon is an occasional complication following a distal radius fracture. Early rupture of the EPL tendon as a complication of distal radius fracture is rare. We report one case of early rupture of the EPL tendon after distal radius fracture.