• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1255-1262
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• 2009

The present study explained the phenomenon that low frequency oscillation is synchronized with discrete data obtained from a wide area system, and a sync search method. When a disturbance occurs in an power system, various controllers operate in order to maintain synchronization. If the system's damping is poor, low frequency oscillations continue for a long time and the oscillations are synchronized with one another at specific frequency. The present study estimated dominant modes, magnitude and phase of signals by applying parameter estimation methods to discrete signals obtained from an power system, and performed sync search among wide area signals by comparing the estimated data. Sync search was performed by selecting those with the same frequency and damping constant from dominant oscillation modes included in a large number of signals, and comparing their magnitude and phase. In addition, we defined sync indexes in order to indicate the degree of sync between areas in a wide area system. Furthermore, we proposed a wide area sync search method by normalizing mode magnitude in discrete data obtained from critical generator of the wide area. By applying the sync search method and sync indexes proposed in this study to two area systems, we demonstrated that sync scanning can be performed for discrete signals obtained from power systems.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.129-138
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• 1993

The shortage of agricultural labour due to industrial growth has greatly induced the mechanization in Korean agriculture. However small and scattered land holdings have been the main constraints in the process of mechanization. This paper describes the interrelationships of farm land structure, machinery selection and machinery operation areas. The sandy silt loam irrigated paddy land having single crop a year was selected as a target areas for this study. Machine operation cost is greatly influenced by operation period, plot geometry and operation area. On the improved geometry plots, optimal machine size increases slowly with increase in operation area. Operable area increases due to increased effective machine capacity on better geometry plot. The difference between the effects of operation period and plot geometry is that in the former case, the cost reduction is caused by delay in increase of machine size, whereas in the latter case timeliness cost is reduced by increase ffective capacity. The effect of farmland consolidation is greater on small plots than that on big plots. Increasing wage rates have induced the adoption of more labor saving machinery. Bigger labor saving machines require enlargement of operation area and larger plots through improvement in farm land structure. Machine cost on poor plot geometry increases more rapidly than that on the good plot geometry and as operation area increases machine cost reduces significantly. It is concluded that the development of agricultural mechanization ion Korea will depend on the improvement in farm land structure and enlargement of operation area.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.3
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• pp.48-54
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• 2000

In this study the characteristics of chip formation of the cold drawn Bi-S free machining steels were assessed. And for comparison those of the cold drawn Pb-S free machining steel the hot rolled low carbon steel which has MnS as free machining inclusions and the conventional steels were also investigated. During chip formation the cold drawn free machining steels show relatively little change in thickness and width of chip compare to those of the conventional carbon steels. And a single parameter which indicates the degree of deformation during chip formation chip cross-section area ratio is introduced. The chip cross-section area ratio is defined as chip cross-section area is divided by undeformed chip cross-section area. The variational patters of the chip cross-section area ratio of the materials cut are similar to those of the shear strain values. The shear stress however seems to be dependent on the carbon content of the materials. The cold drawn Bi-S and Pb-S steels show nearly the same chip forming behaviors and the energy consumed during chip formation is almost same. A low carbon steel without free machining aids shows poor chip breakability due to its high ductility. By introducing a small amount of free machining inclusions such as MnS Bi, Pb or merely increasing carbon content the chip breakability improves significantly.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.351-356
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• 1999

In this study, the characteristics of chip formation of the cold drawn Bi-S free machining steels were assessed. And for comparison, those of the cold drawn Pb-S free machining steel, the hot rolled low carbon steel which has MnS as free machining inclusions and the conventional steels were also investigated. During chip formation, the cold drawn free machining steels show relatively little change in thickness and width of chip compare to those of the conventional carbon steels. And a single parameter which indicates the degree of deformation during chip formation, 'chip cross-section area ratio' is introduced. The chip cross-section area. The variational patterns of cross-section area is divided by undeformed chip cross-section area. The variational patterns of the chip cross-section area ratio of the materials cut are similar to those of the shear strain values. The shear stress, however, seems to be dependent on the carbon content of the materials. The cold drawn BiS and Pb-S steels show nearly the same chip forming behaviors and the energy consumed during chip formation is almost same. A low carbon steel without free machining aids shows poor chip breakability due to its high ductility. By introducing a small amount of non-metallic inclusions such as MnS, Bi, Pb or merely increasing carbon content the chip breakability improves significantly.

• Journal of Korea Multimedia Society
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• v.17 no.10
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• pp.1220-1228
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• 2014

Emergency Warning Service will be the most important service of VANET. Transmission delay is the most important performance criteria of the warning service. Most legacy research takes a way to minimize the packet collision. However those approach has a critical weak point on urban environment where there is a blind area of electric wave. So another issue is required in order to provide enhanced warning message propagation technique to overcome the urban environment problem. In this paper, I proposed an enhanced warning message propagation scheme in the poor electric wave environment as the intersection area. Proposed scheme forwards the warning message to the blind area by enhanced forwarding node selection technique. For efficiency of warning message propagation, I suggest forwarding priority for decision of forwarding node. And the node has a direct mode or redirect mode depending on neighbor nodes. The simulation was carried out to evaluate the performance. The simulation results show that proposed scheme has the superior performance compared to legacy warning message technique.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.6
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• pp.66-78
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• 2003

The purpose of this study was to minimize the forest disturbance around an entry road of a power transmission tower construction site between Taean and Sinsesan, Chungnam. The main study field was classified into existing materials and a GIS, remote sensing analysis, and a field examination. This information was used to identify the most suitable entry road using a degree of green naturality map, eco-naturality map, actual vegetation map, and a forest state map as the existing materials. Also, the study used an normalized difference vegetation index, altitude and slope map in order to make the evaluation materials which used an remote sensing image, and GIS. This data was used to choose an optimum area, and diagnosed the current condition of the vegetation with a field survey of the area. It analyzed vegetation structure, species diversity, the age of trees in a field examination. Subsequently, we proposed four area types based on the analysis results--preservation area, transplantation area, restoration area and development area. As a result, the preservation area was categorized into 8 grades, according to the degree of green naturality, large area of breast diameter at Pinus densiflora community, competition area of Pinus densiflora and Quercus spp. and Quercus spp. community of over 20 years old. A transplantation area established 46 optimum areas according to the GIS analysis and vegetation investigation results. Vegetation restoration plan for disturbance area should be made based on ecological value of existing vegetation to worthwhile area as Quercus spp. mixing forest proposed. The development area selected a ecological worthless place as an artificial forest where Pinus densiflora and Pinus thunbergii growth is poor. This research results suggest that restoration of vegetation will be possible in the real world. Also, ecological restoration guidelines will be made through building and analyzing data base and routine monitoring of transplantation and restoration area.

• Journal of radiological science and technology
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• v.22 no.2
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• pp.9-15
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• 1999

The aim of this study is to measure the application of prone compression study using compression paddle for obese patients in upper gastrointestinal series. Prone compression study using compression paddle was performed in fifty patients, who were not examined completely erect compression study for obesity. The radiographs of stomach were classified into the lower, middle, and high body and then we gave five points included 'very poor', 'poor', 'suspicious', 'good', and 'complete' according to level of detection for area gastrica and mucosal fold. Statistic analysis was performed using T-test and ANOVA, and confidence rate was fixed in 95%(P<0.05) for the significance. The results were as follows : 1. The compression marks on high body was 'poor' grades in erect and prone compression study. The points were 1.64 and 1.86, respectively. 2. The compression marks on middle body was 1.68 in erect compression study, and 'suspicious' in prone compression study. 3. The compression marks on lower body was 'poor' in erect compression study, and 'good' in prone compression study. 4. There was a high statistic signification between the two study on middle and lower body except for high body(P<0.01). 5. The average abdominal thickness of subjects was 23.98 centimeter. There was no statistic signification between the difference of average marks by the abdominal thickness(P>0.05). As these results, the prone compression study in upper gastrointestinal serie seem to be an useful study for obese patients, because it decreases pain and the feeling of uneasiness, and improve compression efficiency remarkably.

• The Journal of Pediatrics of Korean Medicine
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• v.18 no.2
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• pp.127-142
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• 2004

Objective : To evaluate the effect of Oriental medical treatment on a patient with Ramsay Hunt syndrome with poor prognosis on EMG. Methods : We applied various methods of Oriental Medical treatment including Acupuncture, Electroacupuncture, Herb medicine, Vesiculation therapy using Mylabris and Crontonis Fructus, Massage, Self-excercise of face muscles. Results : 1. Herb medicine was applied on the basis of Differentiation of Syndromes(辨證): We tried Herb medicine to improve the function of Digestive System. The patient's stool condition, subjective sensation related with abdominal pain and general condition improved. 2. We used the Vesiculation therapy using Mylabris which was used traditionally to treat Facial Palsy. We powdered Mylabris and mixed it with Crontonis Fructus to make a paste. We put it on Ye-poong(?風), Nae-gwan(內關) at left side. It induced vesicles at the applied area, but it disappeared in 48 hours without any scar. 3. We applied acupuncture, electroacupunture, massage and self-excercise of face muscles. On gross scale assessment, there was some improvement. And assessment with regional scale also showed changes. The patient and the guardian were satisfied with the result. Conclusion : We experienced a case of Ramsay Hunt syndrome with poor prognosis on EMG. She also showed poor response to conservative treatment. Through various modalities of Oriental medical treatment, we attained some clinical improvement.

• The Journal of Korean Physical Therapy
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• v.25 no.4
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• pp.224-231
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• 2013

Purpose: The purpose of this case study was to investigate three poor fibrinolytic responders with chronic ischemic stroke to acute exercise intensity and time. Methods: Three ischemic stroke patients (male) from the stroke center located at Busan metropolitan area in Republic of Korea volunteered at this study. They performed two single session exercises that were a VO2peak test and a single bout treadmill walking (70-75%HRpeak, 30 min, 50min). Fasting blood samples for determination of tissue Plasminogen Activator (tPA) and Plasminogen Activator Inhibitor-1 (PAI-1) were obtained before, immediately after, 30min after acute exercise. SPSS 12.0 was used for analyzing of data and computing mean and standard deviation, and change rate was conducted between times. Results: In fibrinolytic activity according to the intensity and time of acute exercise, tPA change increased steadily during the recovery stage after the VO2peak in the cases, but PAI-1 activity showed different patterns among the cases. In a single bout treadmill walking (70-75%HRpeak, 30 min, 50min), tPA change increased between 30min and 50min. Conclusion: In conclusion, these results suggest that the exercise prescription for poor fibrinolytic responder with three male chronic ischemic stroke patients without motor disability recommend at 70-75%HRpeak, over 30min.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.431-440
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• 2016

Electric or hydrogen energy source is expected to solve a various issues including energy security and exhaust pollution. However, it is required a lot of time and a variety of development to apply for commercialization. Therefore, it is needed to translation fuels between the future and the present. DME (Dimethyl Ether) can play a reduce exhaust emission from medium- to heavy-duty engines that are mostly used in commercial sector. It have applied to the DME fuel as a various alternative fuel including power generation in many countries. Especially, it is necessary to secure the energy of energy-poor areas that are widely distributed around the world. And Korea also has the energy-poor areas due to geographical characteristics. These areas has been covered by their own energy through some small diesel generators, diesel boiler etc. If DME fuels are supplied in new demand such as rural sector with energy poor area, DME fuel will be available in the wider sector. In this study, it investigated performance and emission characteristics of agricultural generator and air heater using DME fuel. So the existing equipment of generator and air heater was modified to apply DME fuel. And combustion characteristics and properties of exhaust gas according to the contents of the DME fuel were evaluated. DME fuel showed a potential application in agricultural generator and air heater.