• Journal of Power System Engineering
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• v.7 no.4
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• pp.12-18
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• 2003

Various measures have been tried to reduce the NOx emission from diesel engine, but with partial success because the mechanisms of NOx and PM formations appear to have trade-off relation between each other. Therefore it has been known to be difficult to reduce NOx emission and PM emission simultaneously. Two stage combustion method i,e. a combustion process which has rich combustion stage and lean combustion stage one by one, has been developed successfully to reduce NOx formation in the continuous combustion chambers such as in the boilers. But until yet it is not successful to apply the same method in intermittent combustion chamber like in the diesel engine cylinder, as it was, only several research works were carried out. In this study, devised was a uniquely shaped combustion chamber with reformed piston crown intended to keep fuel-rich condition during early stage of combustion and fuel-lean condition during next stage. It was found that the NOx emission decreased significantly at various conditions of operation with the two stage combustion type engines of PR20 type, but other values such as smoke, CO and specific fuel consumption deteriorated as usual.

• Journal of Chest Surgery
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• v.23 no.4
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• pp.715-719
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• 1990

Thymoma is defined as a neoplasm of the epithelialreticular framework cells of the thymus. The treatment of choice and the prognosis for patients with thymoma are still controversial subjects due to lack of a uniform histological classification and standardized criteria for typing thymic tumors. Between June 1985 and May 1989, eight patients underwent thymomectomy at the Department of Thoracic and Cardiovascular Surgery, Korea University Medical Center. A clinical analysis was performed and the following result was obtained. In histologic cell type, epithelial type was 2 cases, lymphocytic type 3 cases, and mixed type was 3 cases. The clinical stage was classified by Masaoka’s classification that Stage I was 4 cases, Stage II; 2 cases, Stage III; 2 cases and Stage IV was none. Myasthenia Gravis was associated with thymoma in 5 patients. In 8 patients, thymomectomy were performed. Adjuvant radiotherapy was performed in one patient with Stage I due to suspicious tumor remnant and in Stage II, III patients routinely. Combined chemotherapy was performed in one patient with Stage III due to local recurrence. We concluded that the most important prognostic factor of thymoma is extent of tumor invasion. And the presence of Myasthenia Gravis is no more prognostic factor. Surgical resection of thymoma is treatment of choice, If local invasion or distant dissemination is present, postoperative radiotherapy and /or combined chemotherapy is recommended.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.3
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• pp.366-370
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• 1996

Bilateral cleft lip reconstruction can be performed in one-or two-stages. The choice depends on the surgeon's proficiency and experience. However the type and severity of the cleft must be considered. Complete or incomplete symmetric, bilateral clefts in which the premaxilla is within the alveolar arch or slightly protruded can be successfully treated with simultaneous lip reconstruction on both sides. There are some advantages that one-stage lip reconstruction facilitates creation of a symmetric and balanced lip, retraction of protruding premaxilla and the parent's psychologic satisfaction. However, there are some disadvantages such as micrognathia of the upper jaw by severe scar formation and poor adaptation of flap margins by severe tension. The surgeon must be able to judge and exploit the advantages offered by one-stage approach. We present the case report of one-stage reconstruction of primary bilateral cleft lip with literature reviews.

• Proceedings of The Korean Cleft Lip And Palate Association
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• 1997.06a
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• pp.58-58
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• 1997

• Journal of Korean Institute of Industrial Engineers
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• v.43 no.2
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• pp.147-153
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• 2017

In order to demonstrate a target reliability with a specified confidence level, a new two-stage Bayesian Reliability Demonstration Test (RDT) plans that is known to be more effective than a corresponding single-stage one is proposed and developed by Bayesian framework with beta prior distribution for Weibull life time distribution. A numerical example is provided to illustrate the proposed RDT plans and compared with other non-Bayesian and Bayesian plans. Comparative results show that the proposed Bayesian two-stage plans have some merits in terms of required and expected testing time and probability of acceptance.

• Journal of Chest Surgery
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• v.20 no.3
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• pp.473-482
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• 1987

The records of 65 patients with a confirmed diagnosis of primary lung cancer who underwent surgical therapy at the Department of Thoracic and Cardiovascular Surgery of the Keimyung University Hospital were analyzed during the period of 8 years and 4 months, from August, 1978 to December, 1986. The peak incidence was observed in the 5th decade of life and the mean age was 52.9 years old. Male versus female ratio was 8.3:1 Cough was the most frequent presenting symptom, 76.9% then chest discomfort, hemoptysis and dyspnea followed in order. 44.6% of the patient had 2 months of prediagnostic symptomatic period, 72.3% had 5 months, and the mean was 5.7 months. As for preoperative diagnosis, 62 of total 65 patients revealed the mass lesion on simple chest x-ray, and 56 of 65 patients on bronchoscopic biopsy, 10 of 37 patients on sputum cytology and 15 of 15 patients on computerized tomography of the chest were positive. Of the 65 patients, 35 [53.9%] had squamous cell carcinoma, 18 [27.7%] adenocarcinoma, 3 [4.6%] large cell carcinoma, and 3 [4.6%] small cell carcinoma all which was oat cell carcinoma. 83.1% of the total patient was resectable, and 34 underwent pneumonectomy and 20 lobectomy. Of these 65 operations, 29 was radical resection, 25 palliative, and 11 exploratory thoracotomy. As for clinical stagings, 23 patients were in Stage, I, another 23 in Stage II and 19 in Stage III, while 16 was in stage, I, 14 in stage ll and 35 in stage III in postoperative staging evaluation. In correlation of postoperative TNM classification and radical resection, those patients who had lung cancer of stage I [14/16] and stage II [9/13] had more radical resection. As postoperative complications, one patient had massive bleeding, two empyema, one empyema with bronchopulmonary fistula, and one cardiac herniation. Operative mortality rate was 1.5% [1 patient]. Mean duration between 1st operation and discovering recurrence in 18 patients was 12.7 months.

• Archives of Plastic Surgery
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• v.32 no.3
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• pp.281-286
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• 2005

The goal in facial paralysis treatment is to achieve the normal appearance of the face as well as to reconstruct the natural symmetrical smile. In cases of facial paralysis, a widely accepted procedure is the two stage method, which combines neurovascular free muscle transfer with cross face nerve grafting. Although the results are promising, the two operations of this method, which are about 1 year apart, impose an economic burden on the patients and require a lengthy period before results are obtained. In order to overcome these drawbacks, one stage method, using latissimus dorsi neurovascuular free muscle flap was introduced. Between January 2000 and January 2004, fifteen patients with long standing facial paralysis were treated in the Korea University Anam Hospital. The segmental latissimus dorsi with long nerve and pedicle was transferred to the paralyzed side of the face. The first postoperative movement of the transferred muscle was reported at 8.9 months, faster than that of the two stage method. During the next 24 months, a constant increase in the power of muscle contraction was observed. The fifteen cases were evaluated within an average of 31.7 months following the surgery and satisfactory results including muscle contraction were obtained in eleven of the cases but muscle contraction was not found in three cases.

• Advances in pediatric surgery
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• v.7 no.2
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• pp.130-136
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• 2001

The aim of this study was to evaluate the short-term outcomes of the trans anal one-stage pull-through procedure(TOP) in Hirschsprung's disease. Eight patients aged 3 weeks to 8 months with Hirschsprung's disease underwent this procedure. A rectal mucosectomy was performed from just proximal to dentate line to the level of peritoneal reflexion, where muscle layer was incised circumferentially. Rectosigmoid was mobilized out through the anus, and full-thickness frozen biopsy was taken for confirmation of ganglionic cells. After the rectal muscular cuff was divided longitudinally in the posterior aspect, aganglionic bowel was removed and ganglionic colon was anastomozed to the anus. The mean operating time was 161 minutes, and the mean hospital stay after operation was 3.8 days. Five patients had three to four bowel movement per day without other therapy at mean postoperative 39.2 days. Although long-term follow-up will be required, the TOP might be the new alternative surgical procedure for Hirschsprung's disease.

• Advances in aircraft and spacecraft science
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• v.10 no.3
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• pp.245-256
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• 2023

In order to improve aerodynamic performance of multi-stage axial flow turbines used in aircraft engines, a one-dimensional aerodynamic design and optimization framework is constructed. In the method, flow path is generated by solving mass continuation and energy conservation with loss computed by the Craig & Cox model; Also real gas properties has been taken into consideration. To obtain an optimal result, a multi-objective genetic algorithm is used to optimize the efficiencies and determine values of various design variables; Final design can be selected from obtained Pareto optimal solution sets. A three-stage axial turbine is used to verify the effectiveness of the developed optimization framework, and designs are checked by three-dimensional CFD simulation. Results show that the aerodynamic performance of the optimized turbine has been significantly improved at design point, with the total-to-total efficiency increased by 1.17% and the total-to-static efficiency increased by 1.48%. As for the off-design performance, the optimized one is improved at all working points except those at small mass flow.

• Radiation Oncology Journal
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• v.12 no.2
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• pp.185-190
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• 1994

Purpose : Patients with esophageal cancer treated with surgery plus postoperative radiotherapy or radiation alone were retrospectively analyzed. Method : From August 1980 to June 1992, 93 patients who were treated with 30 Gy or more in the Department of Therapeutic Radiology were evaluated. Median age was 59 years. Ninety one were male and remaining 2 were female. Patients with stage II, III and IV disease were 25, 62 and 6 respectively. Thirteen of the tumor were located in upper one third, 56 in middle one third and 24 in lower one third. Forty three patients had tumors 5cm or less in size and remaining 50 had greater than 5cm. Of those 93 patients, 41 were treated with surgery plus postoperative radiotherapy and 52 with radiation alone. Dose of radiation ranged from 34 to 66.6 Gy. Follow up period was 12 to 61 months. Results : Stage of the tumor was the most important prognostic factor of the evaluated factors. Median survival for entire group of patients was 12 months. Median survival for patients treated with surgery plus postoperative radiotherapy and radiation alone were 15 and 10 months, respectively. There was no difference of 2 year survival. Median survival was 21 months for Stage II and 10 months for Stage m disease. In Stage II disease, that was 21 months for postoperative group and 17.5 months for radiation alone group. Five year survival were $27.5\%$ and $9\%$, respectively. Conclusion : This study showed that the result of surgery plus postoperative radiotherapy was not different from that of radiation alone despite of slightly longer median survival in postoperative group. Also stage of the disease was the most important prognostic factor.