• 전기학회논문지
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• 제58권7호
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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.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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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.

• 한국생산제조학회지
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• 제9권3호
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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.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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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.

• 한국멀티미디어학회논문지
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• 제17권10호
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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.

• 대한방사선기술학회지:방사선기술과학
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• 제22권2호
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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.

• 대한한방소아과학회지
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• 제18권2호
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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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• 제25권4호
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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.

• 한국수소및신에너지학회논문집
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• 제27권4호
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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.

• 사회복지연구
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• 제44권1호
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• pp.113-134
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• 2013

본 연구는 빈곤청소년의 꿈과 미래 설계경험을 탐색하기 위한 목적으로 수행되었다. 연구 수행을 위해 빈곤청소년을 참여자로 선정하여 월드비전 산하의 전국 24개 기관에서 초점집단면접을 진행하였다. 연구 결과 빈곤청소년의 꿈은 경험을 통해 형성되고 주변과의 상호작용을 통해 확장되거나 축소되는 것으로 나타났다. 빈곤청소년은 정서적 및 물질적 지원의 부족으로 인해 꿈의 형성과 발전, 진로 준비로의 구체화 과정에서 어려움을 경험하였고 그 과정에서 주체적으로 노력하는 역량과 가능성도 보여주었다. 이러한 연구 결과를 바탕으로 빈곤청소년의 꿈과 미래에 대한 관심 제고의 필요성 및 체험지향적 진로지도 프로그램의 활성화를 제언하였다.