• Journal of Welding and Joining
• /
• v.34 no.5
• /
• pp.70-76
• /
• 2016

In this study, Microstructure and tensile properties in arc brazed joints of 1000MPa grade DP steel using Cu-Si insert metal were investigated. The fusion zone was composed of Cu phase which solidified a little Fe and Si. The former phase formed due to dilute the edge of base material by arc, although Fe was not solid solution in Cu at the room temperature. Cu3Si particles formed by crystallization at $1100^{\circ}C$ during faster cooling. After the tensile shear test, there are no differences between the brazed joint efficiencies. The maximum joint efficient was about 37% compared to strength of base metal. It is better than that of arc brazed joint of DP steel using Cu-Sn filler metal. Fracture position of all brazing conditions was in the fusion zone. Crack initiation occurred at three junction point which was a stress singularity point of upper sheet, lower sheet and the fusion zone. And then crack propagated across the fusion zone. The reason why the fracture occurred at fusion zone was that the hardness of fusion zone was lower than that of base material and heat affected zone. The correlation among maximum load and hardness of fusion zone and EST at fractured position was $R^2=0.9338$. Therefore, this means that hardness and EST can have great impact on maximum load.

• Journal of Welding and Joining
• /
• v.3 no.1
• /
• pp.22-31
• /
• 1985

Hot straining embrittlement is one of the most important factors which cause the brittle fracture initiation even in the service temperature in the case of mild steel and high tensile steel. Therefore it is necessary to analyze thoroughly the hot straining embrittlement occurred in weld HAZ of the structural steels. The behaviors of plastic deformation and fracture toughness at the notch tip of the hot strained weld HAZ in structural steels (SB 41 KS, SA 588-Grade A ASTM) have been studied by the recrystallization technique and crack opening displacement (COD) test method. The obtained results are summarized as follows; 1. The plastic zone is formed at the notch tip of weld HAZ owing to nomotonic and cyclic hot stran, and the maximum plastic strain increases with the accumulated hot straining amounts. 2. The distribution of the effective strain at the plastic deformed zone in HAZ can be determined as follows; (.epsilon. over bar $_{p}$ )$_{\chi}$=.epsilon. over bar $_{cr}$ ( $R_{/chi}$/.chi.)$^{m}$ where, .epsilon. over bar $_{cr}$ : (SB 41; .epsilon. over bar $_{cr}$ = 0.2, SA 588; .epsilon. over bar $_{cr}$ = 0.1) 3. The embrittlement of weld HAZ in SB 41 and SA 588 is influenced by hot strain, and the degree of embrittlement becomes deeper with hot straining amounts. 4. The embrittlement of weld HAZ of SB 41 is not influenced by the hot straining amounts until .epsilon. over bar $_{max}$ = 0.36, $R_{\chi}$ = 0.065mm, however the embrittlement of structure in SA 588 is considerably influenced even by a small quantity of the hot straining amounts.s.

• The Journal of the Korean bone and joint tumor society
• /
• v.3 no.2
• /
• pp.112-118
• /
• 1997

Multicentric chondrosarcoma other than the mesenchymal subtype is rare separate entity. We experienced a case with nonmonomelic synchronous multicentric chondrosarcoma without any preexisting lesions of Oilier's disease or Maffucci's syndrome. To our knowledge, there was no report of synchronous nonmonomelic multicentric chondrosarcoma. A thirty-three year old man had right distal thigh pain of one and half year. Bone scan showed hot lesions on medial condyle of right femur and shaft of left femur. Plain X-ray showed osteolytic lesion on right femur and slight cortical thickening and calcific lesion was observed on left femoral shaft. Curettage and bone cement filling was done on both lesions. The pathology reports were grade I chondrosarcoma on both side of femur. At one month from operation, pathologic fracture of left femur occurred on bone cement-host bone junction. Conservative treatment and radiotherapy of 60Gy was done. At 8 months from operation, nonunion was evident. Segmental resection of left femur with contralateral fibula graft and second look operation on right condyle lesion were done. At 6 months from revision, fracture occurred at host-graft bone junction. We removed previous hardware and applied long DCP and massive autogenous bone graft. Afterwards, the patient looks good and union was progressing. But at 4 years from last operation, hypertrophic nonunion occurred. Another revision was done with condylar plate and bone graft and now he is well without any sign of local recurrence or metastasis.

• Journal of Bone Metabolism
• /
• v.25 no.4
• /
• pp.227-233
• /
• 2018

Background: Few studies have investigated the effects of sarcopenia on postoperative outcomes including mortality rates following surgery for osteoporotic hip fractures. The purpose of the present study was to determine the prevalence of sarcopenia and the relationship between sarcopenia and 1- and 5-year mortality rates in a consecutive series of patients with osteoporotic hip fractures. Methods: Among patients who underwent hip surgery for osteoporotic hip fractures, this study included 91 patients subjected to abdominal computed tomography within 1 year of hip surgery. We defined sarcopenia using sex-specific cut-off points for the skeletal muscle index at the level of the third lumbar vertebra. All patients were divided into 2 groups according to the presence or absence of sarcopenia and the 1- and 5-year mortality rates were compared. To confirm factors affecting mortality in addition to sarcopenia, we examined patient age, sex, American Society of Anesthesiologists grade, location of fracture, type of surgery, and bone mineral density. Results: The 1- and 5-year mortality rates were 20.9% and 67.2%, respectively. Among the 45 patients with sarcopenia, the 1- and 5-year mortality rates were 22.2% and 82.7%, respectively. Of the 46 patients without sarcopenia, the 1- and 5-year mortality rates were 19.6% and 52.7%, respectively. Results of the Kaplan-Meier analysis showed that sarcopenia did not affect the 1-year mortality rate (P=0.793), but had a significant effect on the 5-year mortality rate (P=0.028). Both perioperative sarcopenia (P=0.018) and osteoporosis (P=0.000) affected the 5-year mortality rate. Conclusions: Sarcopenia increases the risk of 5-year mortality in patients with osteoporotic hip fractures.

• Tunnel and Underground Space
• /
• v.31 no.6
• /
• pp.415-427
• /
• 2021

This technical report briefly introduced the rock cutting splitting method under development. This method is a method of excavating the rock by splitting the block after the rock cutting process. After designing the cutting geometry of the rock face, the chisel is press-fitted to remove the rock block. At this time, when the cutting block is properly designed, the tensile crack propagates smoothly at the bottom of the rock block. An analytical solution was devised to estimate the indentation force required for splitting rock blocks using fracture toughness mode 1 required for tensile crack growth. The impact force of the hydraulic breaker of the excavator was analyzed, and the grade of the excavator that can be constructed according to the rock block design geometry was analyzed.

• Radiation Oncology Journal
• /
• v.33 no.3
• /
• pp.217-225
• /
• 2015

Purpose: To investigate the outcomes of patients with spinal metastases from hepatocellular carcinoma (HCC), who were treated by stereotactic body radiotherapy (SBRT). Materials and Methods: This retrospective study evaluated 23 patients who underwent SBRT from October 2008 to August 2012 for 36 spinal metastases from HCC. SBRT consisted of approximately 2 fractionation schedules, which were 18 to 40 Gy in 1 to 4 fractions for group A lesions (n = 15) and 50 Gy in 10 fractions for group B lesions (n = 21). Results: The median follow-up period was 7 months (range, 2 to 16 months). Seven patients developed grade 1 or 2 gastrointestinal toxicity, and one developed grade 2 leucopenia. Compression fractures occurred in association with 25% of the lesions, with a median time to fracture of 2 months. Pain relief occurred in 92.3% and 68.4% of group A and B lesions, respectively. Radiologic response (complete and partial response) occurred in 80.0% and 61.9% of group A and B lesions, respectively. The estimated 1-year spinal-tumor progression-free survival rate was 78.5%. The median overall survival period and 1-year overall survival rate were 9 months (range, 2 to 16 months) and 25.7%, respectively. Conclusion: SBRT for spinal metastases from HCC is well tolerated and effective at providing pain relief and radiologic response. Because compression fractures develop at a high rate following SBRT for spinal metastases from primary HCC, careful follow up of the patient is required.

• Journal of Trauma and Injury
• /
• v.28 no.3
• /
• pp.190-194
• /
• 2015

Blunt cerebrovascular injury is defined as a vertebral or carotid arterial structural wall injury resulting from nonpenetrating trauma. Complete traumatic internal carotid artery occlusion is very rare condition accounting for 0.08~0.4 0f all trauma patients and believed to be associated with the greatest risk of ischemic stroke reported in 50~90% in a few small series. A 55-year-male was admitted with drowsy mentality and severe headache after a fall down accident. Brain computed tomography showed a subdural hematoma at the both frontal area with a fracture of the occipital skull bone. Two days after admission, he suddenly complained with a right side hemiparesis of motor grade 2. Brain magnetic resonance diffusion demonstrated multiple high flow signal changes from the left frontal and parietal lesion. Computed tomographic angiogram (CTA) revealed absence of the left ICA flow. Trans femoral cerebral angiography (TFCA) showed complete occlusion of the left internal carotid artery (ICA) at ophthalmic segment in the left ICA angiogram and flows on the left whole hemispheric lesions through the anterior communicating artery in the right ICA angiogram. We decided to conduct close observations as a treatment for the patient because of acute subdural hematoma and sufficient contralateral cerebral flow by perfusion SPECT scan. Two weeks after the accident, he was treated with heparin anticoagulation within INR 2~4 ranges. He recovered as the motor grade 4 without another neurologic deficit after 3 months.

• Journal of Korean Neurosurgical Society
• /
• v.29 no.1
• /
• pp.108-112
• /
• 2000

Objective : Many authors suggest that patients with traumatic subarachnoid hemorrhage(tSAH) visible on first CT after heve injury had a significantly worse prognosis than patients who do not. The aim of this study is to identify patients with tSAH who present with a bad prognosis by reviewing their clinicoradiological features and plan appropriate treatments. Patients and Methods : We reviewed and analysed the factors that influenced discharge outcomes in 172 patients with tSAH for a 3-year period. The outcome was divided into good(good recovery and moderate disability of glasgow outcome scale) and good(severe disability, vegetative state and death). Results : A regression analysis of statistical significant factors(p<0.05) among the clinical and CT features ranked them by descending order of contribution to Glasgow Outcome Scale(GOS) scores at the time of discharge from acute hospitalization as follows 1) clinical : admission Glasgow Coma Scale(GCS), hypotension, CT grade, abnormal APTT, skull fracture, hyperglycemia(>160mg/dl), hypoxia, operation, 2) CT : basal cistern effacement(BCE), mass lesion, cortical sulcal effacement(CSE), midline shift. Conclusion : We have also experienced that the CT grading scale proposed by Green et al is a simple and useful prognostic factor. The authors believe that the patients with high CT grade need adjuvant therapies as of well surgery but it seems mandatory to consider early identification and correction of hypotension, hyperglycemia, and hypoxia in emergency setting.

• Clinics in Shoulder and Elbow
• /
• v.5 no.1
• /
• pp.29-36
• /
• 2002

Purpose : Cubitus varus deformity has been reported to cause ulnar neuropathy. We present five cases of tardy ulnar nerve palsy due to cubitus vus and analyzed the factors related to the nerve plasy caused by the deformity. Materials and Methods : Three men and two women were reviewed retrospectively and the mean age of the patients were 26 (range, 14-38). The average interval from initial fracture to nerve palsy was 19 years (8-32 years). The severity of symptoms, according to McGowan's classification, was grade I of 2 patients, grade Ⅱ of 3 patients. Carrying angle was an average of 18。 (30° -45° ). Internal rotation angle measured by Yamamoto's method was an average of 33° (30° -45° ). Results ㆍ The mean follow-up period was 53 months (35-70 months). Elbow pain and numbness of the fingers were relieved shortly after surgery. It revealed that anterior subluxation of the nerve due to internal rotation deformity and compression of the nerve between the medially shifted medial head of triceps and the medial epicondyle. Conclusion : The major entrapment point of the nerve is the fibrous band between the two heads of the flexor carpi ulnaris. The severe internal rotation deformity may contribute the cause of tardy ulnar nerve palsy in cubitus varus deformity.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.103-103
• /
• 2009

As the size of containership increased over 14,000TEU, thick steel plate with high strength has been used. The plate thickness increased over 70mm and yield strength of the steel plate was around $47kg_f/mm^2$. Many researchers reported that the thick welded plate has low crack arrest toughness. They noticed the crack arrest ability is dependent on the plate thickness. In other words, brittle crack propagates straightly along the welded line and make abrupt fracture in the thick plate which causes low $K_{ca}$. In this study, the other factors, especially welding heat input, to cause low crack arrest toughness was investigated for thick steel plate welds. EH grade steel plates were used in this study and 50 to 80 thick plates were tested to confirm thickness sensitivity. Electro gas welding (EGW) and flux cored arc welding (FCAW) were adopted to prepare the welded joints. Temperature gradient ESSO test was performed to measure $K_{ca}$ values with the variation of welding variables. As a result of this study, regardless of plate thickness, welding heat input to cause welding residual stress around crack path is a key factor to control the brittle crack propagation in welded joints.