• Environmental and Resource Economics Review
• /
• v.16 no.1
• /
• pp.99-127
• /
• 2007

When the margin between available capacity and demand is thin in a liberalized electricity market, prices rise steeply and system reliability is threatened. The principal response to these circumstances is often an assumption that price spikes and electricity shortages are the result of a failure to build sufficient new supplying facilities. It is, of course, often the case that additional investments in generation and network facilities would improve reliability, and such investments are often needed. But focusing on additional generation and transmission facilities for restoring balance to the grid overlooks the essential fact that reliability is a function of the relationship between supply and demand, imposing unnecessary costs on electric system. When the relationship is out of balance, the search for solutions must consider not only investments supply-side resources but also cost-effective demand-side resources such as accelerated load management, efficiency measures, and price-responsive load programs. Integrating demand resources into electricity markets can add enormous value to the electric system, widening the capacity margin, lowering costs and enhancing system reliability at the same time. This paper studies several challenges now facing electricity markets: demand-side management-especially, economic effects of demand response, potential reliability problems, market and system operation, CBP market improvements and so on. The paper concludes with a series of policy recommendations in five areas: (i) The Effects of efficient improvement to incorporate demand responses and demand-side resources into modem electricity markets, (ii) Fosteing price based demand response and (iii) improving incentive based demand response, (iv) strengthen demand response analysis and valuation, (v) integrating demand response into resource planning and adopting enabling technologies.

• Radiation Oncology Journal
• /
• v.37 no.1
• /
• pp.37-42
• /
• 2019

Purpose: To identify prognostic factors influencing progression-free survival (PFS) of aggressive fibromatosis (AF) after postoperative radiotherapy (PORT) and assess correlations between immunohistochemistry (IHC) features of β-catenin/smooth muscle actin (SMA) and PFS. Materials and Methods: Records of 37 patients with AF treated by PORT from 1984 to 2015 were retrospectively reviewed. Fifteen patients underwent wide excision for AF and 22 patients received debulking operation. The median total dose of PORT was 59.4 Gy. IHC staining results of β-catenin and SMA were available for 11 and 12 patients, respectively. Results: The median follow-up duration was 105.9 months. Five-year PFS rate was 70.9%. Tumor size or margin status was not related to PFS in univariate analysis (p = 0.197 and p = 0.716, respectively). Multivariate analysis showed that increased interval from surgery to PORT (>5.7 weeks) was a marginal risk factor for PFS (p = 0.054). Administration of PORT at the initial diagnosis resulted in significantly improved PFS compared to deferring PORT after recurrence (p = 0.045). Patient with both risk factors of deferring PORT after recurrence and interval from surgery to PORT >5.7 weeks had significantly lower 5-year PFS than patients without risk factor (34.1% vs. 100.0%; p = 0.012). Nuclear β-catenin intensity tended to inversely correlate with 5-year PFS, although it did not reach statistical significance (62.5% at low vs. 100.0% at high; p = 0.260). SMA intensity was not related to PFS (p = 0.700). Conclusion: PORT should be performed immediately after surgery irrespective of margin status or tumor size especially in recurrent case. Nuclear β-catenin staining intensity of IHC might correlate with local recurrence.

• Tuberculosis and Respiratory Diseases
• /
• v.44 no.3
• /
• pp.505-515
• /
• 1997

Background : We assessed the accuracy of staging in evaluation of bronchial invasion, thus found the role of CT in patients who underwent resective surgery in primary lung cancer. Materials and Methods : Authors retrospectively analized the preoperative CT scans of 156 patients receiving pneumonectomy(n = 95) and lobectomy(n = 61). Among lobectomy patients, 7 patients subsequently performed pneumonectomy because of positive resection margin of bronchus in frozen biopsy. We also retrospectively analized CT scans of non-operated 60 patients who performed sufficient bronchoscopic biopsy. Bronchial wall thickness more than 3mm, irregular wall thickening and reduction of diameter by CT were defined as bronchial invasion. The pathologic examination of resection margin were positive in 20, stump recurrence occurred in 6 of the operated group, and the pathologic examination of biopsy of bronchial wall were positive in 34 of the non operated group, and these were an regarded as bronchial invasion. Results : The CT assessment of bronchial invasion revealed low sensitivity (11.5%), low positive predictability(38%), but high specificity(96%) and relatively high accuracy (84%) in the operated group and higher sensitivity (62%), higher positive predictability(95%) in non-operated group. Conclusion : In lung cancer patients who underwent operation, CT showed very low sensitivity and positive predictability in evaluation of bronchial invasion. Because the usefulness of CT in evaluation of bronchial invasion is limited, therefore aggressive fiberoptic bronchoscopic biopsy is thought to be necessary before surgical attempt.

• Radiation Oncology Journal
• /
• v.13 no.1
• /
• pp.41-48
• /
• 1995

Purpose : The adjuvant postoperative radiotherapy has been usually applied to the patients with unfavorable prognostic factors after radical operation in early cervical cancer. We focused on the evaluation of the survival status and failure patterns of the patients with postoperative radiotherapy. Materials and Methods : We retrospectively analyzed ninety patients with FIGO stage IB and IIA cervix cancer who received postoperative pelvic irradiation at Chonnam University Hospital between August 1985 and December 1988, Seventy-eight patients had adequate follow-up information for survival analysis. Median follow-up time of these patients was 64 months. Results : The 5 year overall and disease free survival rate of ninety patients was $80.0\%$ and $80.2\%$, respectively. The prognostic significance to the survival was determined by multivariate analysis. Adequacy of resection margin(p=0.005) and lymph node status(p=0.005) appeared to be independent prognostic factors. Recurrence occurred in 13 patients, 5 in the pelvis and 8 at distant sites. The median time to recurrence was 19 months(range:3-39 months). The pelvic recurrence was more prevalent in the group of patients with adenocarcinoma, depth of stromal invasion more than 10mm and use of chemotherapy. The distant failure was more prevalent in the group of positive resection margin or positive lymph node with statistical significance. Conclusion : Patients with pelvic lymph node or surgical margin involvement clearly constitute a high risk group in this analysis and should be considered as candidates for some form of adjuvant therapy.

• Journal of Chest Surgery
• /
• v.41 no.3
• /
• pp.386-389
• /
• 2008

Lung parenchyma is a common organ for metastases of extrathoracic tumors, but endobronchial metastasis is very rare. In this report, we present a case of endobronchial metastases from renal cell carcinoma (RCC), and this was managed by performing operative resection. A 63-year-old man presented with frequent dry cough; he had previously undergone left nephrectomy and postoperative chemotherapy for grade 2 RCC eight years ago. Computed tomography and bronchoscopy showed an endobronchial tumor from the left lower lobe bronchus to the second carina, and this mass was diagnosed as a necrotic tissue with chronic inflammation at biopsy. During the operation, the mass was revealed to be a metastatic renal cell carcinoma on the frozen section diagnosis and there was no mucosal invasion on the resection margin of the left lower lobe bronchus. We performed lobectomy of the left lower lobe with systemic dissection of the mediastinal lymph nodes. The final histopathologic diagnosis of the endobrochial mass was metastatic RCC and any mediastinal lymph node metastasis was not found. The patient was discharged on postoperative day 10 without any postoperative complications.

• Journal of Gastric Cancer
• /
• v.13 no.1
• /
• pp.51-57
• /
• 2013

Purpose: Additional gastrectomy is needed after endoscopic resection for early gastric cancer when pathology confirms any possibility of lymph node metastasis or margin involvement. No studies depicted the optimal type of surgery to apply in these patients. We compared the short-term and long-term outcomes of laparoscopic gastrectomy with those of open gastrectomy after endoscopic resection to identify the optimal type of surgery. Materials and Methods: From 2003 to 2010, 110 consecutive patients who underwent gastrectomy with lymphadenectomy either by laparoscopic (n=74) or by open (n=36) for gastric cancer after endoscopic resection were retrospectively analyzed. Postoperative and oncological outcomes were compared according to types of surgical approach. Results: Clinicopathological characteristics were comparable between the two groups. Laparoscopic group showed significantly shorter time to gas passing and soft diet and hospital day than open group while operation time and rate of postoperative complications were comparable between the two groups. All specimens had negative margins regardless of types of approach. Mean number of retrieved lymph nodes did not differ significantly between the two groups. During the median follow-up of 47 months, there were no statistical differences in recurrence rate (1.4% for laparoscopic and 5.6% for open, P=0.25) and in overall (P=0.22) and disease-free survival (P=0.19) between the two groups. Type of approach was not an independent risk factor for recurrence and survival. Conclusions: Laparoscopic gastrectomy after endoscopic resection showed comparable oncologic outcomes to open approach while maintaining benefits of minimally invasive surgery. Thus, laparoscopic gastrectomy can be a treatment of choice for patients previously treated by endoscopic resection.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.6
• /
• pp.9-15
• /
• 2005

In this research the discharge characteristics of logic gate of the discharge logic gate plasma display panel with the NOT-AND logic function newly designed was analyzed. As for this discharge logic gate a logical output is induced by controlling the voltage between the electrodes using the discharge path. From the experimental result the discharge characteristics of logic gate is influenced by the interrelation of the voltages appling two vertical electrodes. To in the application possibility to large screen PDP, the discharge characteristics by the line resistance of the electrode was evaluated In result it has been inferred that the influence which the drop of voltage by the line resistance of two vertical electrodes exerts on the discharge of the logic gate is minute. Through the experiment, the optimized values of the pulse voltages and the current limitation resistances of each electrode which composed the discharge logic gate were obtained and maximum operation margin of 49[V] was obtained.

• Archives of Reconstructive Microsurgery
• /
• v.15 no.2
• /
• pp.65-69
• /
• 2006

Purpose: We performed vastus lateralis (VL) muslce or myocutaneous flap for close of the trochanteric skin defect usually happened in paraplegia and report our 6 cases. Materials and Methods: Between March 2004 and August 2005 we performed 4 cases of VL muscule flap with skin graft and 2 cases of VL myocutaneous flap for close of the trochanteric skin defect in 6 paraplegia patients. There were 5 men and 1 woman and mean age was 52.2 years and mean diameters of skin defect was $8.3{\times}8.3\;cm$. The mean follow up period was 18 months. The survival of flap, complications, healing time and patient's satisfaction were evaluated. Results: All flaps were survived except 1 case of margin necrosis. In 2 cases, blood-serous discharges were continued after operation which might be due to dead space and treated with $2{\sim}3$ times debridement and delayed close. Mean time to heal the skin defect was 7.6 weeks. No infection and recurrence in follow up periods. Cosmetic results judged by patients are that 3 cases are good and 3 cases are fair. Conclusion: VL muscle and myocutaneous flap is good treatment method among the numerous methods in treatment-failed cases of trochanteric skin defects of paraplegia patients. This surgical procedure is simple, constant blood supply, good pliability, cosmetic results and also appliable to other skin defect of pelvis girdle like sacrum and ischium.

• Journal of the Korean Institute of Gas
• /
• v.17 no.1
• /
• pp.7-12
• /
• 2013

As emission regulation for vehicle has been reinforced, many researches carried out for HCNG(hydrogen-natural gas blends) fuel to the conventional compressed natural gas (CNG) engine. However, abnormal combustion such as backfire, pre-ignition or knocking can be caused due to high combustion speed of hydrogen and it can result in over heating of engine or reduction of thermal efficiency and power output. In the present study, improvement of combustion performance was observed with HCNG fuel since it can extend a flammability limit. Knocking characteristics for CNG and HCNG fuel were investigated. Feasibility of HCNG fuel was evaluated by checking the knock margin according to excess air ratio. The operation of engine with HCNG was stable at minimum advance for best torque(MBT) spark timing and knock phenomena were not detected. However, it is necessary to prepare higher knock tendency since possibility of knock is higher with HCNG fuel.

• Radiation Oncology Journal
• /
• v.12 no.3
• /
• pp.369-376
• /
• 1994

This is a retrospective analysis of 64 patients who was treated with postoperative radiation therapy after radical hysterectomy and bilateral pelvic lymphadenectomy (53 patients) or total abdominal hysterectomy(11 patients) for uterine cervix cancer between May 1980 and September 1991 at the Department of Radiation Oncology, Kyung Hee University Hospital. Most patients were FIGO IB (31 Patients) and IIA (25 patients), and median period of follow-up was 5.1 years. Of these patients,24 received adjuvant whole pelvis irradiation of 6000 cGy and 40 received 5000-5500 cGy whole pelvis irradiation and/or intracavitary radiation (7 Patients). The actuarial overall and relapse free 5 year survival rate were $71.0\%$, $68.3\%$ respectively. The survival rates by stage were $79.1\%$ in stage I, and $61.2\%$ in stage II. Treatment failure was noted in 18 of 64 patients ($28.1\%$), Iocoregional failure in 8 ($12.5\%$), distant metastasis in 8 ($12.5\%$), paraaortic node metastasis in 1 and one patient and concurrent locoregional and distant metastasis. The univariate analysis of prognostic factors affecting to overall survival rate represented lymph node status, the number and site of metastatic lymph node, parametrial invasion, the thichness of cervical wall invasion, and size of cancer mass. Histology, vessel invasion, endometrial extension, hemoglobin level. resection margin status, age, radiation dose were not significant prognostic factors. Complication relating to operation and postoperative radiation were variable according to radiation therapy method: 6000 cGy RT group 8/24($33.3\%$), 5000-5500 cGy+ICR 3/7 ($42.9\%$), 5000-5500 cGy external RT only group 3/33 ($9.1\%$). In conclusion, the results suggest that postoperative radiotherapy is necessary in high risk patients for locoregional control and improving survival rate, and higher dose does not improve results but only increases complication.