• Structural Engineering and Mechanics
• /
• 제17권1호
• /
• pp.99-112
• /
• 2004

It is known that lap splices in the longitudinal reinforcement of reinforced concrete (RC) bridge columns are not desirable for seismic performance, but it is sometimes unavoidable. Lap splices were practically located in the potential plastic hinge region of most bridge columns that were constructed before the 1992 seismic design provisions of the Korea Bridge Design Specification. The objective of this research is to evaluate the seismic performance of reinforced concrete (RC) bridge piers with lap splicing of longitudinal reinforcement in the plastic hinge region, to develop an enhancement scheme for their seismic capacity by retrofitting with glassfiber sheets, and to assess a damage of bridge columns subjected to seismic loadings for the development of rational seismic design provisions in low or moderate seismicity region. Nine (9) test specimens with an aspect ratio of 4 were made with three confinement ratios and three types of lap splice. Quasi-static tests were conducted in a displacement-controlled way under three different axial loads. A significant reduction of displacement ductility was observed for test columns with lap splices of longitudinal reinforcements, whose displacement ductility could be greatly improved by externally wrapping with glassfiber sheets in the plastic hinge region. A damage of the limited ductile specimen was assessed to be relatively small.

• 대한두개안면성형외과학회지
• /
• 제21권2호
• /
• pp.109-113
• /
• 2020

Sinus pericranii is a rare vascular anomaly characterized by abnormal venous communication between the inner and outer regions of the cranial cavity. Here, we report a case of sinus pericranii and venous malformations in the right periorbital region of a 2-year-old girl. Radiologic findings showed venous malformations in the right parietal region communicating with the superior sagittal sinus in the intracranial region. There were notable improvements following surgical resection for the abnormal venous lesions and several sclerotherapies. Presence of a bluish and pulsating mass on the scalp, which showed bruit on auscultation, may indicate sinus pericranii, which should be included in the differential diagnosis.

• Archives of Plastic Surgery
• /
• 제32권2호
• /
• pp.175-182
• /
• 2005

Skull base tumors have been determined inoperable because it is difficult to accurately diagnose the extent of the involvement and to approach and excise the tumor safely. However, recently, the advent of sophisticated diagnostic tools such as computed tomography and magnetic resonance imaging as well as the craniofacial and neurosurgical advanced techniques enabled an accurate determination of operative plans and safe approach for tumor excision. Resection of these tumors may sometimes result in massive and complex extirpation defects that are not amenable to local tissue closure. The purpose of this study is to analyze experiences of skull base reconstruction and to evaluate long term survival rate and complications. All cranial base reconstructions performed from July 1993 to September 2000 at Department of Plastic and Reconstructive Surgery of the Seoul National University Hospital were observed. The medical records were reviewed and analysed to assess the location of defects, reconstruction method, existence of the dural repair, history of preoperative radiotherapy and chemotherapy, complications and causes of death of the expired patients. There were 12 cases in region II, 8 cases in region I and 1 case in region III according to the Irish classification of skull base. Cranioplasty was performed in 4 patients with a bone graft and microvascular free tissue transfer was selected in 17 patients to reconstruct the cranial base and/or mid-facial defects. Among them, 11 cases were reconstructed with a rectus abdominis musculocutaneous free flap, 2 with a latissimus dorsi muscluocutaneous free flap, 1 with a fibular osteocutaneous free flap, 2 with a scapular osteocutaneous free flap, and 1 with a forearm fasciocutaneous free flap, respectively. During over 3 years follow-up, 5 patients were expired and 8 lesions were relapsed. Infection(3 cases) and partial flap loss(2 cases) were the main complications and multiorgan failure(3 cases) by cancer metastasis and sepsis(2 cases) were causes of death. Statistically 4-years survival rate was 68%. A large complex defects were successfully reconstructed by one-stage operation and, the functional results were also satisfactory with acceptable survival rates.

• Geomechanics and Engineering
• /
• 제13권3호
• /
• pp.489-504
• /
• 2017

The localized shear and the slip lines are easily observed in elastic-brittle-plastic rock. After yielding, the strength of the brittle rock suddenly drops from the peak value to the residual value, and there are slip lines which divide the macro rock into numbers of elements. There are slippages of elements along the slip lines and the displacement field in the plastic region is discontinuous. With some restraints, the discontinuities can be described by the combination of two smooth functions, one is for the meaning of averaging the original function, and the other is for characterizing the breaks of the original function. The slip lines around the circular opening in the plastic region of an isotropic H-B rock which subjected to a hydrostatic in situ stress can be described by the logarithmic spirals. After failure, the deformation mechanism of the plastic region is mainly attributed to the slippage, and a slippage parameter is introduced. A new analytical solution is presented for the plane strain analysis of displacements around circular openings. The displacements obtained by using the new solution are found to be well coincide with the exact solutions from the published sources.

• 동력기계공학회지
• /
• 제13권2호
• /
• pp.30-35
• /
• 2009

Numerical Calculations for dimensionless pressure drop (friction factor times Reynolds number) have been obtained for fully developed laminar flow of MPL(Modified Power Law) fluid in isosceles triangle pipes. The solutions are valid for Pseudoplastic fluids over a wide range from Newtonian behavior at low shear rates through transition region to power law behavior at higher shear rates. The analysis identified a dimensionless shear rate parameter which for a given set of operating conditions specifies where in the shear rate range a particular system is operating, i.e., Newtonian, transition or power law region. The numerical calculation data of the dimensionless pressure drop for the Newtonian and power law regions are compared with previously published asymptotic results presenting within 0.16 % in Newtonian region and 2.98 % in power law region.

• Archives of Plastic Surgery
• /
• 제45권6호
• /
• pp.588-592
• /
• 2018

Harvesting grafts from the anterior iliac bone has been associated with various complications. A 50-year-old woman presented to our department with a chief complaint of right inguinal swelling and pain. Autologous bone grafts had been harvested on two previous occasions from the right anterior iliac crest for use in the reconstruction of multiple facial fractures. Computed tomography and magnetic resonance imaging revealed a full-thickness bone defect in the right anterior iliac crest. A mass was noted in the right gluteus minimus, while a multilocular cystic mass extended from the right iliac crest defect to the right inguinal region. Both the inguinal mass and gluteal mass were removed under general anesthesia. Following histopathological analysis, the gluteal mass was diagnosed as a venous malformation (VM). Based on the patient's clinical course, iliac bone graft harvesting and trauma to the gluteal region triggered hemorrhaging from the VM. Blood components leaked out from the fragile portion of the iliac bone defect, forming a cystic lesion that developed into the inguinal mass. In this case, a coincidental VM resulted in a rare complication of iliac bone graft harvesting. These sequelae could have been avoided by planning for more appropriate ways to collect the grafts.

• Archives of Plastic Surgery
• /
• 제34권4호
• /
• pp.504-507
• /
• 2007

Purpose: Chondroid syringoma, previously known as 'mixed tumor of the skin', is a rare benign tumor. It usually presents an asymptomatic solitary firm intradermal or subcutaneous slowly growing nodule. It occurs frequently in the head and neck region of middle-aged men. We would like to report an uncommon chondroid syringoma about the clinical and histologic presentation. about the clinical and histologic presentation. Methods: We experienced two cases of chondroid syringoma on the nose and the upper lip, each other. Both masses were totally excised with clear margin. Results: On histologic examination, the masses showed a biphasic pattern-an epithelial component exhibiting apocrine/eccrine differentiation and a stromal component exhibiting myxoid/collagenous change-consistent with the diagnosis of chondroid syringoma. There have been no evidence of recurrence and malignant transformation during postoperative follow-up. Conclusion: There is no one distinctive clinical feature that is specific for chondroid syringoma. However, it should be included in the differential diagnosis of a solid nodule in head and neck region with long standing duration, such as epidermal inclusion cyst, pilomatrixoma, dermoid cyst, sebaceous cyst, neurofibroma, and basal cell carcinoma.

• Archives of Plastic Surgery
• /
• 제49권3호
• /
• pp.289-295
• /
• 2022

Background Massive weight loss (MWL) is a very common presentation that you may face as a plastic surgeon. Each patient has his own individual criteria, so, you should work according to a well-organized plan, especially when such cases have concerns about their gluteal area contour that were neglected before by many surgeons. A decision-making strategy was used to give a personalized treatment for targeting gluteal region reshaping of MWL patients. Methods This study considered all patients with MWL subjected to buttock reshaping. There was no randomization in treatment; there was a case-by-case assessment. We analyzed the features of the buttocks, the type of surgery performed, the outcomes, and the complications. Results Fifty two patients were included (41 females and 11 males), ages ranged between 21 and 66 years. Demographic data, preoperative body mass index (BMI), duration of surgery, type of surgery, and postoperative complications were collected. Statistically significant improvements were observed in gluteal ptosis and patient satisfaction grades. Conclusion Aesthetic improvement of the buttocks involves either augmentation or contouring that may be obtained by liposculpture, surgical lifting, or combination. Patients with MWL have high expectations and are often treated with multiple procedures. Thus, an easy strategic approach personalized on each patient to treat multiple adjacent areas in one operation is necessary. Adipose tissue distribution, gluteal skin status, and BMI were the main factors that can forcefully affect our plan to guarantee reduction of unpleasant results and complications and improve patient satisfaction.

• 대한두개안면성형외과학회지
• /
• 제17권1호
• /
• pp.35-38
• /
• 2016

Chondroid synringoma (CS), pleomorphic adenoma of skin, is a benign tumor found in the head and neck region. CS was first reported in 1859 by Billorth for the salivary gland tumor. The usual presentation is an slowly growing, asymptomatic mass. A 53-year-old female with a history of chondroid synringoma had presented with multiple firm, nodular masses found in the left nostril area. The lesion had been excised 8 years prior and was diagnosed histopathologically, but had gradually recurred. Excision of the mass located in subcutaneous layer revealed four whitish, firm tumors surrounded with capsular tissue. Neither recurrence nor complications occurred during the 18 months follow-up period. In the head and neck region, chondroid syringoma should always be considered in differential diagnosis of soft tissue masses despite its rare incidence. For that reason, excisional biopsy with clear margin is the optimal diagnostic as well as therapeutic choice. We report a case of recurred chondroid syringoma on the nose in female patient.

• 한국항공우주학회지
• /
• 제33권12호
• /
• pp.39-47
• /
• 2005

본 연구에서는 고속 충격환경을 경험하는 플라스틱 구조 소재에 대한 인장속도별 물성 평가 시험 및 구조건전성 평가에 음향방출 기법을 적용하였다. 인장속도별 물성 평가시험을 통하여 플라스틱 소재 구조물의 건전성 평가에 유용한 음향방출 신호 특성 인자들을 획득하였다. 인장속도에 따른 인장강도는 저속 인장속도 구간에서는 속도가 증가함에 따라 강도가 증가하는 특성을 보여주었으나 일정 속도 영역 이상의 고속 인장시험에서는 인장속도 증가와 무관하게 일정한 강도 값을 나타내었다. 정적 압축 구조시험에서는 음향방출 기법을 적용함으로써 플라스틱 쉘 구조물의 균열발생 시점 및 위치 등을 정확히 평가할 수 있었다.