• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.53 no.12
• /
• pp.637-644
• /
• 2004

This paper proposes an expert system with the knowledge learning capability which can enhance the safety and effectiveness of substation operation in the automated substation as well as existing substation by inferring multiple events such as main transformer fault, busbar fault and main transformer work schedule under multiple inference mode and multiple objective mode and by considering totally the switch status and the main transformer operating constraints. Especially inference mode includes the local minimum tree search method and pattern recognition method to enhance the performance of real-time bus reconfiguration strategy. The inference engine of the expert system consists of intuitive inferencing part and logical inferencing part. The intuitive inferencing part offers the control strategy corresponding to the event which is most similar to the real event by searching based on a minimum distance classification method of pattern recognition methods. On the other hand, logical inferencing part makes real-time control strategy using real-time mode(best-first search method) when the intuitive inferencing is failed. Also, it builds up a knowledge base or appends a new knowledge to the knowledge base using pattern learning function. The expert system has main transformer fault, main transformer maintenance work and bus fault processing function. It is implemented as computer language, Visual C++ which has a dynamic programming function for implementing of inference engine and a MFC function for implementing of MMI. Finally, it's accuracy and effectiveness is proved by several event simulation works for a typical substation.

• Ocean and Polar Research
• /
• v.36 no.3
• /
• pp.303-318
• /
• 2014

The rising global demand for energy resources may lead to greater interest in the Arctic region. Since it has various resources, such as oil and gas, and large potential as a strategic location in exploration and production (E&P), there is likely to occur island sovereignty issues between the five arctic costal states and other countries. While global warming has led to the opening of the Northeast Passage and the Northwest Passage, several obstacles may impede the development of this area such as the low temperature environment, infrastructure problems in a limited area, flow assurance, environmental regulations, etc. To overcome these problems, various techniques have been applied in the exploration, development, production, transportation, and environment fields and it seems to be made technical development in extreme environment. In this study, the E&P status of representative states and development technologies in the Arctic region have been summarized with regard to carrying out E&P related to drilling, development, production, and operation in oil and gas fields. Furthermore, environmental factors have been taken into account to enhance progress with regard to E&P and ensure sustainable development in the Arctic. On that basis, it will be possible to secure oil and gas field development, production technology and R&D infrastructure in the Arctic.

• Current Photovoltaic Research
• /
• v.4 no.4
• /
• pp.159-163
• /
• 2016

Piled snow upon PV module interferes with Photoelectric Effect process through photovoltaic directly. As a result of this phenomenon, its generation efficiencies keep decreasing or are stuck at zero power generating status. In addition, PV facilities have been installed on those places such as water surface, roof-top, and other isolated places, dealing with conditions of "Securing high REC weighted value", "Difficulty of securing land" and so forth. Through this study, we are able to actualize the function of heating over PV modules when it snows. We adopted laminating method through heating film and modules, guaranteeing warranty more than for 25 years. Also we are trying remote control systemically, not by hardware control, to run parallel with automatic driving and monitoring system which enable to control operation time, insolation, amount of snowfall automatically. We applied analysis of actual proof to both snow removal PV system and general PV power system, and these led to bear power consumption analysis while snow-removing, and its comparison after finishing the task as "One stone, two birds." In the long run, we could carry out economic analysis against snow removal system, and this helps to verify the most maximized control method for snow removal conditons on a basis of weather information. this study shall let prevent people from negligent accidents, and improve power generation problems as mentioned from the top. Ultimately, we expect to apply this system to heavy snowfall regions in winter season in spite of its limited system installaion in Korean territory, initially.

• The Korean Journal of Community Living Science
• /
• v.14 no.3
• /
• pp.89-98
• /
• 2003

To assess the actual status of businesses selling fermented soybean products, this study surveyed 130 Farmhouse style small size soybean sauce processing sites supported by the Rural Development Administration nationwide. The sex composition of the businesses representatives of 2% male and 98% female showed that a farmhouse soybean processing business is generally operated by rural women as a non-filming business. The percentage of co-worked sites was 71.2 and that of sites with permits was 39.2. The main products were meju, doenjang, and kanjang. Total production volume was found to be 523 tons, 256 tons, and 135 k$\ell$s, respectively. The number of years of experience of the manufacturers of the kanjang and doenjang was found to be 25.7 on average which shows that long-experienced, skilled manufacturers are participating in this project. The traditional measuring unit differed greatly depending on the region. This difference in the measuring unit of soybeans resulted in a large difference in the volume of doenjang and kanjang produced Per Province. For one kg of raw soybeans, the weight of Doenjang produced also varied from 2.14 kg in the Gyeongbuk area to 1.62 kg in Jeju. In the aspect of salt use, 1.75 $\ell$ (translated by volumetric unit 0.704 due) of salt pet kg of meju, in Jeju, was the highest in Korea. Government supervision would be beneficial in the areas of raw material products, standardization of measuring units and production methods, organization and operation of a conference for the different groups of producers, and in construction of a nationwide database.

• Journal of Digital Convergence
• /
• v.18 no.10
• /
• pp.437-442
• /
• 2020

Information boards installed in Seoul subway stations are currently in four languages: Korean, English, Chinese, and Japanese. Informational announcements are provided to inform the main information or operation information through the LCD monitor installed in the train and in Korean. However, users are confused because the subway guide board screen displays advertisements more heavily than driving information As a research method, we grasped the current status and problems of the subway guide board installed on the Seoul subway, and presented an improved new subway guide board drafts. An online survey was conducted on 67 people, ranging from teens to 60s who mainly use the Seoul Metro. As a result of the study, the screen design is different for each boarding route, so it is necessary to unify the subway guide board that provides only necessary information. In particular, since the user transfers the subway several times in order to move from place to place, the subway guide board design should function as an emergency disaster guide or boarding information, not an advertising signboard.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.5
• /
• pp.465-469
• /
• 2010

Air heater used in power plant helps increase the thermal efficiency of the boiler by recovering the heat from the boiler flue gas and thus preventing the loss of useful heat. This study investigates the effect of preventive maintenance on the performance of the air heater in a power plant. Performance indexes for the air heater are calculated to observe the changes in the performance and operation status of the air heater before and after preventive maintenance. The major performance indexes considered are temperature efficiency of the flue gas side, air leakage rate, heat recovery rate, heat transmission rate, and heat capacity ratio. The performance of the air heater is evaluated before and after preventive maintenance; our results show that all the abovementioned performance indexes are improved after the maintenance.

• Journal of Chest Surgery
• /
• v.22 no.6
• /
• pp.1092-1100
• /
• 1989

Since May 1987 to April 1989, fifteen patients have been subjected to coronary artery bypass graft [CABG] including coronary thromboendarterectomy in 3 patients at Hanyang University Hospital. The correlation between the preoperative coronary angiography, electrocardiography, clinical status, operative finding and postoperative blood flow, complication and degree of clinical improvement were evaluated. 1. Ten patients [67 %] were male and five patients [33 %] were female, Ages ranged from 30 to 68 years. [average 52.2 years] 2. The angina by types of presentation was stable in 3 patients, unstable in 12 patients with resting, postinfarction and progressive angina as the criteria of unstability. 3. The number of involved vessels were single in 6 cases, double in 4 cases, triple in 5 cases including 1 case of left main coronary arterial disease. 4. The distribution of sites of distal anastomosis revealed predilection to left coronary arterial system [83 %], especially left anterior descending arterial system. 5. The author performed 4 cases of single bypass, 4 cases of double bypass, 5 cases of triple bypass and 2 cases of quadruple bypass. Of these 15 patients, 3 patients received coronary thromboendarterectomy, LAD in 2 patients and right coronary artery [RCA] in 1 patient. 6. The distal anastomosis were performed first with using saphenous vein grafts as conduits in all cases except 1 case using Gore-Tex conduit because of deficient in length and narrowed internal mammary artery and sequential bypass methods were employed in last 6 cases. 7. One operative death occurred and therefore, mortality rate was 6.7%. The perioperative myocardial infarction were occurred in 3 cases [20%] and its cause was supposed that they were triple vessel disease and therefore, aortic cross clamping times were relatively long. 8. All survivors were followed for 17.7 months on an average [range 5-28 months] and they have had symptomatic improvement except 1 case having mild degree of angina at 1.5 months after operation.

• Journal of Chest Surgery
• /
• v.36 no.8
• /
• pp.590-594
• /
• 2003

Vascular injury has been increased with popular outside activities. However there are only a few studies for vascular trauma. We intended to find out the relationships between the vascular trauma and its prognosis. Material and Method: Forty-four patients were diagnosed and operated on for vascular injury in the Gyeongsang National University Hospital from 1992. to 1999. We reviewed their chart and analysed their data retrospectively. We studied to causes, treatments, and prognoses of traumatic vascular injury. Result: The transfer time between accident place and emergency department was mean 3,5 hour, and the operation preparing time was 8.8 hours. Five cases required amputation of extremity. All amputation cases were combined with communited bony fractures. Thirty-eight cases had combined other injuries, and almost combined injuries were muscular and neurological damages, Conclusion: The optimal treatment plan for vascular trauma was prompt diagnosis and quick management. It may decrease amputation rate and post-traumatic complications. Therefore we must be carefully evaluated the multiple traumatic patients for early diagnosis of vascular injury and operate quickly in emergency status.

• Journal of Chest Surgery
• /
• v.33 no.4
• /
• pp.285-289
• /
• 2000

Background: For AVR using conventional prosthetic valves in adult patients with a narrow aortic root, aortic root enlargement is necessary to reduce postoperative pressure gradient across the aortic valve (ΔP). An evaluation of early and mid-term results of aortic root enlargement with AVR and echocardiographic follow up of ΔP and left ventricular function was performed. Method: From Aug. 1991 to Feb. 1998, eighteen patients aged 17 to 59 years(mean, 38$\pm$12 years) underwent Manouguian procedure with AVR. Aortic annular circumstance was enlarged 10.0mm to 18.0mm(mean, 12.6$\pm$6.3mm). Eight patients(44.0%) had NYHA class III status before operation, and seven cases of them underwent concomitant MVR. Valve pathology was ASr in 6 cases, AS in 4 cases, nd ASr+MSr in 8 cases. Replaced valve size was 21mm in 8 cases and 23 mm in 10 cases, and St. Jude Medical mechanical valve was used in 10 cases and Carbomedics in 8 cases. Result: Follow-up duration was 6 to 57 months (mean, 26$\pm$18 months), and total follow-up was 287 patient-year. There were one hospital death and one late death, therefore, actuarial survival rate was 85.7% at 56 months. Peak ΔP wad decreased significantly at postoperative mid-term period as 13$\pm$5mmHg, compared with thepreoperative one (42$\pm$8mmHg) (p<0.01). LVM(gm/$m^2$) was also diminished as 35.8%(115$\pm$36gm/$m^2$)at postoperative mid-term period, compared with preoperative one (179$\pm$56gm/$m^2$)(p<0.05). Conclusion: There were no specific complications related to the procedure. And we could have adequate enlargement of aortic annulus to suitable prosthetic valve that have no effect of patient-prosthese mismatch.

• Archives of Reconstructive Microsurgery
• /
• v.17 no.1
• /
• pp.36-41
• /
• 2008

Surgical treatment of compressive ulnar neuropathy at the elbow has been performed with a wide variety of techniques. Among these techniques, anterior submuscular transposition of the ulnar nerve has been regarded as the method of choice by many authors. It has many advantages including a low recurrence rate, scar-free vascular bed, and protection from repeated trauma to the nerve. However, anterior submuscular transposition is technically demanding and requires more extensive soft tissue dissection. On the other hand, anterior subfascial transposition is less invasive, requires a relatively shorter operation time than the submuscular technique, and also can be done safely even in patiensts with elbow arthritis. We evaluated the clinical results of anterior submuscular transposition compared with anterior subfascial transposition. Fifteen patients underwent anterior submuscular transposition and ten patients underwent anterior subfascial transposition of the ulnar nerve. The mean follow-up time was 15 months (range 10 to 38 months) in the anterior submuscular transposition group and 7 months (range 6 to 15 months) in the anterior subfascial transposition group. According to the outcome status determination algorithm devised by Mowlavi, 3 patients (20%) showed total relief, 10 patiensts (66.7%) improvement and 2 patients (13.3%) no changes in the anterior submuscular transposition group. In the anterior subfascial transposition group, 2 patients (20%) showed total relief, 7 patients (70%) improvement and 1 patient (10%) displayed no changes. Statistically there was no significant difference of the clinical results between the two surgical techniques. Therefore we would suggest anterior subfascial transposition of the ulnar nerve as a preferred method for treatment of cubital tunnel syndrome.