• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.297-302
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• 2003

To ensure a safe operation of the prototype KGT-74 ㎾ small gas turbine, vibrational reliabilities of the compressor 1st, 2nd. and 3rd stages and turbine blades have been estimated and reviewed. FE analyses have been tarried out to obtain the natural vibration characteristics of the blades, and impact modal testings have been performed on every each one of the blades to measure their 1st natural frequencies. Then, the Campbell diagram analyses have been carried out to Judge the safety of the blades from resonant failures up to 6k harmonics. Results show that the compressor 1st stage blade is exposed to a potential resonant failure with 3k harmonic around a rated speed of 30,000rpm but that the other compressor 2nd and 3rd stages and turbine blades are safe from resonant failures. Finally. 27,900 rpm Is selected as the safe operation limit for the KGT-74 ㎾ gas turbine relative to the blade vibrations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.4
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• pp.100-105
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• 1998

This paper proposes a new control strategy of bidirectional uninterruptible power supply (UPS) with the performance of active power filter which compensates the harmonics and reactive power. With only one power stage, it is working simultaneously as the AC/DC rectifier/battery charger and DC/AC inverter to the operation of battery charging or back-up power supplying. Therefore the operation of the proposed system can be divided into the modes, such as the active power filter mode and the battery back-up power mode. And a novel closed-loop control strategy is used to calculate the reference current. The performance of the proposed 5[kVA] system is verified by the simulation and experimental results.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.61-66
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• 2008

Recently, portable devices which require small area and low power consumption employ applications using 3D graphics such as 3D games and 3D graphical user interfaces. We propose an efficient clipping engine algorithm which is suitable in 3D graphics pipeline. The clipping operation is divided into two steps: one is the selection process in the transformation engine and the other is the pixel clipping process in the scan conversion unit. The clipping operation is possible with addition of simple comparator. The clipping for the Y-axis is achieved in the edge walk stage and that for the X and Z-axis is performed in the span processing. The proposed clipping algorithm reduces the operation cycles and the area of of 3D graphics pipelines. We designed a 3D graphics pipeline with the proposed clipping algorithm using Verilog-HDL and verifies the operation using an FPGA.

• Journal of Korean Foot and Ankle Society
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• v.15 no.2
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• pp.51-57
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• 2011

Pilon fractures involving distal tibia remain one of the most difficult therapeutic challenges that confront the orthopedic surgeons because of associated soft tissue injury is common. To introduce and describe the diagnosis, current treatment, results and complications of the pilon fractures. In initial assessment, the correct evaluation of the fracture type through radiographic checkup and examination of the soft tissue envelope is needed to decide appropriate treatment planning of pilon fractures. Even though Ruedi and Allgower reported 74% good and excellent results with primary open reduction and internal fixation, recently the second staged treatment of pilon fractures is preferred to orthopedic traumatologist because of the soft tissue problem is common after primary open reduction and internal fixation. The components of the first stage are focused primarily on stabilization of the soft tissue envelope. If fibula is fractured, fibular open reduction and internal fixation is integral part of initial management for reducing the majority of tibial deformities. Ankle-spanning temporary external fixator is used to restore limb alignment and displaced intraarticular fragments through ligamentotaxis and distraction. And the second stage, definitive open reduction and internal fixation of the tibial component, is undertaken when the soft tissue injury has resolved and no infection sign is seen on pin site of external fixator. The goals of definitive internal fixation should include absolute stability and interfragmentary compression of reduced articular segments, stable fixation of the articular segment to the tibial diaphysis, and restoration of coronal, transverse, and sagittal plane alignments. The location, rigidity, and kinds of the implants are based on each individual fractures. The conventional plate fixation has more advantages in anatomical reduction of intraarticular fractures than locking compression plate. But it has more complications as infection, delayed union and nonunion. The locking compression plate fixation provides greater stability and lesser wound problem than conventional implants. But the locking compression plate remains poorly defined for intraarticular fractures of the distal tibia. Active, active assisted, passive range of motion of the ankle is recommended when postoperative rehabilitation is started. Splinting with the foot in neutral is continued until suture is removed at the 2~3 weeks and weight bearing is delayed for approximately 12 weeks. The recognition of the soft tissue injury has evolved as a critical component of the management of pilon fractures. At this point, the second staged treatment of pilon fractures is good treatment option because of it is designed to promote recovery of the soft tissue envelope in first stage operation and get a good result in definitive reduction and stabilization of the articular surface and axial alignment in second stage operation.

• Radiation Oncology Journal
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• v.16 no.3
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• pp.245-250
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• 1998

Purpose : This study was to evaluate survival, failure patterns, and prognostic factors of stage I squamous cell carcinoma of the glottic larynx after curative radiation therapy. Materials and Methods : A retrospective analysis was done for 57 patients with glottic cancer who were treated with curative radiation therapy from June 1985 to November 1992. There were 55 male and two female patients. Patients' age ranged from 17 to 71 years(median 39 years). Radiation therapy was delivered five times a week, 2 Gy daily, total 66 Gy using 6 MV X-ray. Results : Complete response(CR) was noted in 51 out of 57 patients (89.5%) and persistent disease (PER) in six out of 57 patients(10.5%). The disease-free survival rates at 3 and 5 years were 72.9% and 63.8%, respectively. Seven failures were observed among 51 CR patients during follow-up. Salvage total laryngectomy for six recurred patients and partial laryngectomy for one recurred patient were done with successful results, i.e., all of them were actually salvaged. Among six PER patients, salvage total laryngectomy for two patients and partial laryngectomy for two patients were done and two patients refused operation. Following salvage surgery for the four PER patients, three were salvaged and one failed locoregionally. Among the 13 failures 10(76.9%) were salvaged with surgery. The ultimate local control rate at 5 years was 92.3% and overall 47 out of 57 (82.5%) patients were able to preserve their larynx. The 5-year disease-free survival rates were 85.5% for posterior lesions, and 61.6% for anterior lesions(P<0.05). Cord mobility, involvement of anterior commissure, field size, and T stage did not impact on disease-free survival. Conclusion : Considering the high percentage of voice preservation with initial radiotherapy, radiotherapy should be the first choice in the treatment of stage 1 glottic carcinoma.

• Journal of Chest Surgery
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• v.29 no.1
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• pp.43-51
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• 1996

From march 1989 to October 1993, 57 patients were diagnosed and operated for primary non-small cell lung cancer, and evaluated clinically. 1. There were 45 males and 12 females (M:F=3.8:1), and the peak incidence of age was 6th decade of life (45.6%). In the preoperative diagnostic methods and their positive rate, sputum cytology was 11%, bronchial washing cytology 50%, bronchoscopic biopsy 73%, and CT guided percutaneous needle aspiration biopsy 83%. 3. Histopathologically, squamous cell carcinoma was 56.1%, adenocarcinoma 22.8%, bronchioloal veolar cell carcinoma 1%, and undifferentiated large cell carcinoma 1.8%. 4. In the operation, pneumonectomy was 35.1%, lobectomy 38.6%, bilobectomy 3.5%, segmentec tony 7%, and exploratory thoracotomy 15.8%, and overall resectability was 84.2%. 5. In postoperative stagings, stage I was 28.1%, st ge II 22.8%, stage IIIa 31.6% and stage IIIb 17.5%. 6. Postoperative complications were developed in 11 cases (19.3%) and operative mortality was none. 7. One year survival rate in rejectable cases was 87.0%, 2 year 61.6% and 5 year 44.9%. According to stage, 3 year survival rate was 75.8% in stage I, 16.9% in stage II, 60.9% in stage IIIa, 50% in stage IIIb.

• Membrane Journal
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• v.23 no.1
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• pp.1-11
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• 2013

Poly(ether imide) (PEI)-poly(dimethylsioxane) (PDMS) composite membranes and their modules were prepared, which are capable of selective $CO_2$ separation from the mixture gas. The gas flow rate, concentration, recovery ratio of $H_2$ and removal ratio of $CO_2$ outflowing by stage-cut were characterized at $25^{\circ}C$ and the constant pressure. In addition, to increase the recovery ratio of $H_2$, one stage, two stage series connection, and three stages series + parallel connection tests were carried out. When the stage-cut was 0.32 for the three stages connection operation, the concentration $H_2$ of the produced gas and the recovery ratio of $H_2$ was 97% and 85%, respectively. And also the removal ratio of $CO_2$ was 90% was obtained and the recycled gas concentration was similar with that of the feed gases.

• Journal of Chest Surgery
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• v.43 no.4
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• pp.364-374
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• 2010

Background: We assessed the early and mid-term results of the modified Norwood procedure for first-stage palliation of hypoplastic left heart syndrome (HLHS) and its variants to identify the risk factors for hospital mortality. Material and Method: Between March, 2003, and December, 2009, 23 patients (18 males and 5 females) with HLHS or variants underwent the modified Norwood procedure. The age at operation ranged from 3 to 60 days (mean, $11.7{\pm}13.2days$) and weight at operation ranged from 2.2 to 4.8 kg (mean, $3.17{\pm}0.52kg$). We used a modified technique that spared the anterior wall of the main pulmonary artery in 20 patients. The sources of pulmonary blood flow were RV-PA conduit in 15 patients (group I) and RMBTS in 8 (group II). Follow-up was completed in 19 patients (19/20, 95%) in our hospital (mean $26.0{\pm}22.8months$). Result: Early death occurred in 3 patients (3/23, 13%), of whom 2 had TAPVC. Fourteen patients underwent subsequent bidirectional cavopulmonary connection (BCPC, stage 2) and seven underwent the Fontan operation (stage 3). Three patients died between stages, 2 before stage 2 and one before stage 3. The estimated 1-year and 5-year survival rates were 78% and 69%, respectively. On multivariate regression analysis, aberrant right subclavian artery (RSCA) and associated total anomalous pulmonary venous connection (TAPVC) were risk factors for hospital mortality after stage 1 Norwood procedure. Conclusion: HLHS and its variants can be palliated by the modified Norwood procedure with low operative mortality. Total anomalous pulmonary venous connection adversely affects the survival after a stage 1 Norwood procedure, and interstage mortality rates need to be improved.

• Radiation Oncology Journal
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• v.14 no.3
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• pp.221-228
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• 1996

Purpose : We tried to evaluate the clinical characteristics, the treatment methods, the results of treatments, and the Patterns of failure in ovarian dysgerminoma retrospectively According to the results we would like to suggest the proper management guideline of stage la ovarian dysgerminoma patients who want to maintain fertility. Materials and Methods : Between 1975 and 1990, 34 patients with ovarian dysgerminoma were treated at the Yonsei University Hospital. The case records of these patients have been reviewed for presenting symptoms, treatment methods, local control and survival following treatment. Excluded from analysis were five patients with mixed ovarian germ cell tumors and gonadoblastomas (46,XY) Treatment results of the twenty nine patients were analysed by each treatment modality. Twenty one patients were treated with surgery and postoperative adjuvant radiotherapy (group 2). The other eight patients were treated with operation alone (group 2). The median age of twenty-nine patients was 23 years with a range of 8 to 39 years. Presenting symptoms were abdominal mass (20) pelvic discomfort or pain (5) et al. Radiotherapy was performed by 10MV LINAC or Co-60 teletherapy unit. The total radiation dose of the whole abdomen was 20-25 Gy/3weeks, 1-1.5 Gy/fraction with a boost to the whole pelvis 10-15 Gy/l-2weeks 1.8-2.0 Gy/fraction. Advanced stage disease (stage II or stage III) patients received prophylactic mediastinal and supraclavicular irradiation to a dose of 16-26 Gy. Median duration of follow-up of living patients was 80 months (range 13-201 months). Results : All of the twenty one patients of group 1 were alive without disease ($100\%$). Among the eight patients who were not treated with radiotherapy (group 2), six patients developed local recurrence. Four Patients referred with recurrent disease were treated with salvage radiotherapy. Three of four patients were salvaged and one Patient who had recurrent intra-abdominal disease died of progressed carcinomatosis at 11 months after salvage radiotherapy. The other two patients with recurrence were salvaged with chemotherapy (1 patient) or re-operation (1 Patient). Twenty eight patients remained alive without disease at last follow up, so the 5 year local control rate and 5 year overall survival rate for all groups were $96.6\%$ (28/29), respectively. Among thirteen patients with stage la unilateral tumors seven patients were treated with postoperative radiotherapy and the other six patients were treated with unilateral salpingo-oophorectomy alone. Five patients who did not received radiotherapy developed local failure but all of the recurrent ovarian dysgerminomas were salvaged with radiotherapy, chemotherapy or re-operation. So all the 13 patients with stage la ovarian dysgerminoma were free of disease from 20-201 months (median 80 months). Conclusion : The authors consider external irradiation to be an effective treatment as a complement to surgery in ovarian dysgerminoma. For those patients with disease presenting in stage la tumors who wish to maintain fertility, unilateral salpingo-oophorectomy alone may be curative and spare ovarian function considering excellent salvage rate of recurrent ovarian dysgerminoma in present study.

• Journal of Chest Surgery
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• v.44 no.2
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• pp.169-177
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• 2011

Background: Video-assisted thoracic surgery (VATS) lobectomy has been performed with increasing frequency over the last decade. However, there is still controversy as to its indications, safety, and feasibility. Especially regarding lung cancer surgery, it is not certain whether it can reduce local recurrences and improve overall survival. Materials and Methods: We retrospectively reviewed 1,067 cases of VATS lobectomy performed between 2003 and 2009, including the indications, postoperative morbidity, mortality, recurrence, and survival rate. Results: One thousand and sixty seven patients underwent VATS lobectomy for the following indications: non-small cell lung cancer (NSCLC) (n=832), carcinoid tumors (n=12), metastatic lung cancer (n=48), and benign or other diseases (n=175). There were 63 cases (5.9%) of conversion to open thoracotomy during VATS lobectomy. One hundred thirty one (15.7%) of the 832 NSCLC patients experienced pathologic upstaging postoperatively. The hospital mortality rate was 0.84% (9 patients), and all of them died of acute respiratory distress syndrome. One hundred forty-nine patients (14.0%) experienced postoperative complications. The median follow-up was 22.9 months for patients with NSCLC. During follow-up, 120 patients had a recurrence and 55 patients died. For patients with pathologic stage I, the overall survival rate and disease-free survival rate at 3 years was $92.2{\pm}1.5%$ and $86.2{\pm}1.9%$, respectively. For patients with pathologic stage II disease, the overall survival rate and disease-free survival rate at 3 years was $79.2{\pm}6.5%$ and $61.9{\pm}6.6%$, respectively. Conclusion: Our results suggest that VATS lobectomy is a technically feasible and safe operation, which can be applied to various lung diseases. In patients with early-stage lung cancer, excellent survival can be also achieved.