고온 내산화성 고 Si , Mo 구상흑연주철의 특성에 관한 연구

김석원,우기도,한상원,김정규,김대영 ( Sug Won Kim,Kee Do Woo,Sang Won Han,Jung Ku Kim,Dae Yong Kim ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.2

N/A The physical and chemical characteristics of Ductile Cast Iron(DCI) have been well known because of many studies about DCI. So it has a wide application in the field of heavy and automobile industry because DCI has a good combination of excellent castability and good mechanical properties. But its usage has been often restricted to use in parts such as exhaust manifold required high heat resistance in automobile industry. So, in this study, in order to achieve high heat resistance in DCI, DCI with addition of high Si and Mo alloy elements have been researched on mechanical properties, including heat resistances systematically. With the increase of Mo and Si content, the size and number of graphite in matrix of DCI increased and the pearlite in DCI matrix is transferred to ferrite because of Si strong former of ferrite, otherwhile carbide in matrix increased because of Mo carbide former. In the test of oxidation property, Si and Mo played an important role to retard oxidation of DCI. By the: addition of Si and Mo, the Charpy impact energy was decreased, whereas the total hardness was increased. (Received February 20, 1998)

크롬주철의 기계적 성질에 미치는 합금원소 ( V , Ti ) 와 열처리의 영향에 관한 연구

김석원,김동건,이의권,장호열 ( Sug Won Kim,Dong Keon Kim,Eui Kwoon Lee,Ho Yeal Jang ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.6

N/A The study aims to investigate the influence of alloying elements(V, Ti) and heat treatment on the mechanical properties in hypo-eutectic chromium cast iron. Before heat treatment, all of the specimen were fully annealed(950℃×5hr) to homogenize their structures. The influence of heat treatment and alloying elements(V, Ti) on hardness, retained austenite volume, and charpy impact energy as well as tensile strength of the specimen was tested systematically. Retained austenite decreased with the increase of V and Ti, but incresed with the increase of number of cycles. The impact energy decreased, and hardness and tensile strength increased with the increase of alloying elements (V, Ti) and the decrease of the number of cycles. The hardness and tensile strength increased, but impact energy decreased with the increase of V and Ti elements and the temperature of destabillization heat treatment. After the destabillization heat treatment at the same temperature, the impact energy is increased, while hardness and tensile strength decreased as the increase of tempering temperature. Retained austenite increased with increase of destabilizatoin heat treatment temperature, while decrease with the increase of tempering temperature.

Al-SiCp 복합재료에서 SiCp 의 용해거동에 관한 연구

김석원,이의권,전우용 ( Sug Won Kim,Eui Kweon Lee,Woo Yeoung Jeon ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.4

N/A Aluminum base composites reinforced with various amount of SiC particles and Mg contents have been investigated by different fabrication method for twenty-years. In this paper, how the decomposition and dissolution behaviors of SiCp(20㎛) in the melt of Al composites arised was studied. As the results, the decomposition and dissolution of SiCp into the melt of Al composites increased with increase of the temperature above 720℃, and holding time at a given melting temperature. Because SiC is thermodynamically unstable in this Al-SiCp composite at temperature above the liquidus, SiCp dissolves and reacts with Al in matrix to form Al₄C₃according to following chemical equation 4Al+3SiC→Al₄C₃+3Si, Si decomposed and dissolved from SiCp increases Si content of matrix, while liquidus temperature of matrix decrease with increase of SiC content in matrix. The hardness of SiCp decreased with increase of the melting temperature, the hardness of the matrix /particle interface increased with increase of the melting temperature due to increase of the Mg₂Si and Al₄C₃intermetallic compounds, etc.

결합 유리피판을 이용한 상지 복합결손의 재건

김석원,이준복,이성준,설철환,서동완,Kim, Sug Won,Lee, June Bok,Lee, Sung Jun,Seul, Chul Hwan,Seo, Dong Wan 대한미세수술학회 2004 Archives of reconstructive microsurgery Vol.13 No.1

Advances in microvascular techniques and refinements in microsurgical tissue transfers have enabled surgeons to combine different tissue components and reconstruction into a single-stage operation in extensive or composite defect following injury. Some problems and consideration for extensive or composite defects are form, shape, function, and dimension of the defect sites. Therefore combination of two or more flaps is required to reconstruct extensive or composite defect. This paper presents our clinical experience of four cases of combined free flaps with or without sequential microanastomosis in reconstruction of upper extremity based on peroneal flowthrough, thoracodorsal, and dorsalis pedis vascular system. Satisfactory results were obtained without flap loss and complications. The free flaps were combined in th following fashion; two cases by bridge fashion, one by chimeric microanastomosis and one by simple chimeric fashion. The median follow-up time on all patients was 21.7 months. Donor site morbidity was minimal. Extensive soft tissue or composite defects can be effectively covered by various combined flaps. Even though the risk for complication exists, the options of combination with or without sequential microanastomosis can add a functional or sensory dimension to reconstruction of complex wounds.

Al-Si / SiCp 복합조직에 미치는 Rheo-compocasting 의 제조조건 및 Mg 첨가의 영향

김석원,이의권,전우용 ( Sug Won Kim,Eui Kweon Lee,Woo Yeoung Jeon ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.6

N/A Dispersion behaviors of SiC particles and microstructures in Al-2%Si/SiCp composite prepared by Rheo-compocasting were studied with change of fabrication conditions(slurry temperature, agitation time) and additions of Mg(0∼3wt.%). Also, the microhardness change of matrix, interface and total in composites were examined with additions of Mg (0∼3wt.%). The dispersion of particles in the composites became relatively homogeneous with increase of Mg additions, agitation time and decrease of slurry temperature. Rate of occupied area by particle in matrix was increased as increase of Mg additions due to improvement of wettability between SiC particle and matrix. A favorable composites were obtained by melting under Ar atmospheric SiCp injection and bottom pouring system. According to the analysis of X-ray diffraction, Mg₂Si, Al₄C₃, SiO₂and MgO, etc, intermetallic compounds were formed by chemical interreaction at interface of matrix and particles. The microhardness of interface is higher than that of matrix due to more strengthening of above intermetallic compounds. It was considered that the total hardness of the composites is improved by dispersing of SiCp and addition of Mg.

말초신경 손상 후 측측문합을 이용한 신경이식시 신경이식의 수에 따른 신경재생 및 근육 기능 회복에 관한 비교 연구

김석원,정윤규,강상윤,조필동,Kim, Sug-Won,Chung, Yoon-Kyu,Kang, Sang-Yoon,Cho, Pil-Dong 대한미세수술학회 2001 Archives of reconstructive microsurgery Vol.10 No.1

Recovery of nerve injury is conditioned by various factors including physical state, injured site, cause of injury, and neurorrhaphy Many researchers have reported on regeneration of nerve using end to side neurorrhaphy. The purpose of this study was to examine regeneration of nerve in various conditioned side to side neurorrhaphy. Total of 25 male Sprague-Dawley rats weighing 220 to 250 gm were divided into five groups of five rats each. The group 1, sham group, composed of dissection only without nerve transaction. The group 2, control group, composed of nerve division only without neurorrhaphy or sural nerve graft. The group 3 composed of one segmental sural nerve graft between the tibial and peroneal nerve after division. Group 4 had two segment graft, and the group 5 with three segment graft, each segment being 6mm long and 5 mm apart. The side to side neurorrhaphy was performed between peroneal nerve and tibial nerve using segmental sural nerve graft in rats. We exposed the sciatic nerve, tibial nerve, peroneal nerve, and sural nerve on left side with prone position. The peroneal nerve was cut on the bifurcation site from tibial nerve and the side to side epineurial neurorrhaphy was performed between peroneal nerve and tibial nerve through 6 mm sural nerve segment graft with 11-0 nylon under operating microscope. The electromyography and the weight from ipsilateral tibialis anterior muscle was performed at one month after neurorrhaphy Peroneal and tibial nerve was examined at distal and proximal to the neurorrhaphy site by methylene blue stain under light microscope for histologic appearance. The number of nerve fibers were counted using the image analyzer. Statistically, both in electromyography and number of nerve fibers, the differences in values between the groups were significant.

족배부 복합 피부-건 유리피판을 이용한 Achilles건의 일단계 재건술

김석원,이원재,서동완,정윤규,탁관철,Kim, Sug Won,Lee, Won Jai,Seo, Dong Wan,Chung, Yoon Kyu,Tark, Kwan Chul 대한미세수술학회 2000 Archives of reconstructive microsurgery Vol.9 No.2

The soft tissue defects including the Achilles tendon are complex and very difficult to reconstruct. Recently, several free composite flaps including the tendon have been used to reconstruct large defects in this area in an one-stage effort. Our case presents a patient reconstructed with free composite dorsalis pedis flap along with the extensor digitorum longus and superficial peroneal nerve for extensive defects of the Achilles tendon and surrounding soft tissue. A 36-year-old-man sustained an open injury to the Achilles tendon. He was referred to our department with gross infection of the wound and complete rupture of the tendon associated with loss of skin following reduction of distal tibial bone fracture. After extensive debridement, $6{\times}8cm$ of skin loss and 8cm of tendon defect was noted. Corresponding to the size of the defect, the composite dorsalis pedis flap was raised as a neurosensory unit including the extensor digitorum longus to provide tendon repair and sensate skin for an one-stage reconstruction. One tendon slip was sutured to the soleus musculotendinous portion, the other two were sutured to the gastrocnemius musculotendinous portion with 2-0 Prolene. The superficial peroneal nerve was then coaptated to the medial sural cutaneous nerve. The anterior tibial artery and vein were anastomosed to the posterior tibial artery and accompanying vein in an end to end fashion. After 12 months of follow-up, 5 degrees of dorsiflexion due to the checkrein deformity and 58 degrees of plantar flexion was achieved. The patient was able to walk without crutches. Twopoint discrimination and moving two-point discrimination were more than 1mm at the transferred flap site. The donor site healed uneventfully. Of the various free composite flaps for the Achilles tendon reconstruction when skin coverage is also needed, we recommand the composite dorsalis pedis flap. The advantages such as to control infection, adequate restoration of ankle contour for normal foot wear, transfer of the long tendinous portion, and protective sensation makes this flap our first choice for reconstruction of soft tissue defect including the Achilles tendon.

복합 내측 족저부 및 내측 족부 피판을 이용한 광범위 족저부 결손의 재건

김석원,민완기,홍준표,정윤규,Kim, Sug Won,Min, Wan Kee,Hong, Joon Pio,Chung, Yoon Kyu 대한미세수술학회 2000 Archives of reconstructive microsurgery Vol.9 No.2

The reconstruction of soft tissue defects of the sole requires to stand the force of weight bearing, provide sensation and adequacy for normal foot-wear. Although certain local flaps have been described and used for resurfacing the foot, extensive injury requires distant or free flaps for coverage. There is no doubt that the ideal tissue for resurfacing the sole is the plantar tissue itself. The specialized dermal-epidermal histology and fibrous septa of the subcutaneous layer gives its unique property to stand the pressure and to absorb the shock upon gait. This paper presents a case of reconstructing the sole that involves about 70% of the weight bearing portion. The combined medial plantar and dorsalis pedis chimeric free flap based on the medial plantar artery and medial plantar nerve adds another dimension in resurfacing the weight bearing sole of moderate to large sized defects.

구상흑연주철의 3상혼합조직의 변태거동에 관한 연구

김석원,김동건,유선경 ( Sug Won Kim,Dong Keun Kim,Seon Kyung Yo ) 한국주조공학회 1991 한국주조공학회지 Vol.11 No.5

N/A Ductile cast iron(DCI) with a multi-phase(ferrite-bainite-martensite) structures was produced by various special heat treatment. Intercritical heat treatment(I. C.), intermediate heat treatment(I. M.) and step quenching(S. Q.) were used to strengthen and toughen the fracture initiation sites such as graphite-marix interfaces and eutectic cell boundaries in DCI. The purpose of this study was to investigate of DCI by the special heat treatment. (I. C., I. M., and S. Q.) At a result, bainite nucleation rate at higher temperature was higher than that of at lower temperature, and shapes of bainite and martensite became bar /spheroidal type with increase of isothermal transformation time.

구상흑연주철의 강인화에 미치는 특수열처리와 합금원소의 영향

김석원,최용선 ( Sug Won Kim,Young Seon Choi ) 한국주조공학회 1990 한국주조공학회지 Vol.10 No.4

N/A Ductile cast iron has a good ductility and ductility and toughness than those of gray cast iron, because the shape of graphite is spheroidal. It has been reported that the strengthening and toughening of the ductile cast iron was resulted from the good modification of various matrix structures obtained by the heat treatment or addition of alloying elements. This study aims to investigate the effect of various special heat treatment(Cyclic Heat Treatment, Intermediate Heat Treatment, Step Quenching), austempering and alloying element(Ni) on the strength and toughness of ductile cast iron. The results obtained from this study are summarized as follows. 1) With addition of Ni, the amount of pearlite or bainite were increased and the morphologies of pearlite or bainite became finer by special heat treatments. 2) As the Ni added and not added ductile cast iron were treated by austenitizing at 900℃ and 840℃, in the latter the austenite was mostly formed in the vicinity of eutectic cell boundary, but in the former on the whole matrix. 3) In cyclic heat treatment, the volume fraction of pearlite was increased and the shape of pearlite was fined with increase of the number of cycle. 4) The shape of pearlite was mostly bar type in the intermediate heat treatment, but spheroidal type in step quenching. 5) The mechanical properties of ductile cast iron containing 1.5%Ni austempered at 400℃ for 25min. after austenitizing at 900℃ for 15min. were a good value of hardness 105 (HRB), impact energy 12.5(㎏.m), tensile strength 112(㎏/㎟) and elongation 6.8(%).