• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1384-1386
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• 2005

This paper focuses on development of load test simulator of a steam turbine-generator in a nuclear power plant. When load is taken off from electrical power network, it is very difficult to effectively control the steam flow to turbine of the nuclear turbine-generator, because of disturbances, such as electrical load and network unbalance on electrical network. Up to the present time, the conventional control system has been used for the load control on nuclear steam generator, owing to the easy control algorithms and the advantage which have been proven on the nuclear power plant. However, since there are problems with stability control during low power and start-up, only a highly experienced operator can operate during those procedures. Also, a great deal of time and an expensive simulator is needed for the training of an operator. The KEPRI is developed simulator for 600MW nuclear power plant to take a test of generator load rejection, throttle valve, and turbine load control. Total load test is implemented before start up.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.135-140
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• 2005

Currently, ECDIS and GPS plotters are much used as equipment providing operators with route information, but they do not have any function of automatic route creation and route explanation, so available for only experienced operators. Especially, the present situation is tint no study is made of the automatic route creation and route explanation using ENC for ECDIS, substitution system of paper chart. ENC is the electronic navigation chart that is produced using S-52, S-57 standard format required by IHQ. In this paper, an Vessel Operator Support System(VOSS) is proposed to generate an optimal route where ENC and GPS data is fusioned induding the wind direction and speed of an anemometer and tide data. The proposed system was testified by a simulation, and its effectiveness was verified.

• Journal of Biosystems Engineering
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• v.5 no.2
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• pp.58-66
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• 1980

A survey was conducted to investigate the power tiller accidents. Eight provinces were covered for this study, and 278 power tiller owners were selected randomly by computer random generator. The results are summarized as follows : A. Frequency of accident. (1) Each power tiller had an accident 0.98 times a year and once every 361 hours of use. Higher frequency of accident was found during the miscellaneous operations including the preparation for farming operation, and there was one accident for every 92 hours of use. (2) The power tiller, which are more than six years old, met an accident 1.19 times a year , or one every 311 hours of use. This value was the highest one compared with any other group. (3) Kerosene engine power tillers met an accident 0.97 times a year, or one every 389 hours of use. It was one tie a year, or once every 329 hours of use for diesel engine power tillers. (4) Among diesel-engine power tillers, 10 horse-power group showed a higher frequency tillers. B. Cause of accident (1) The accidents of power tiller were mainly of sefety , which occurred due to the lack of attention during the operation and 47.4% of the total accidents. The next was of accidental, which represented 26.3% of the total accidents. (2) High percentage of safety accidents occurred during the preparation for farming operation including adjustment. Most of the accidental accidents occurred during the transportation. (3) Lower frequency of accident was found in the power tiller group which were operated by the 21-40 years old operator in comparison with that of the power tiller which was operated by other age group. Power tillers which were operated by high school graduates experienced less accidents compared to other education levels. C. Damage by accident (1) Eighty seven pescents of the total accidents caused damage to the power tiller operator , and 13 % of the total accidents caused property damage only. (2) With regard to the damage to the power tiller operator, 73.8% of the total accidents caused light injury but 26.3% caused heavy injury. (3) Accidents which occurred during machine preparation , and farming operations caused minor injury to the operator, but the accidents during transportation caused heavy injury which cost more than 15 days for recovery. (4) Among the 39 accidents , which caused property damage 18 accidents were from the transportation . Among the total property damage accidents 53.8% were light one which cost only less than 1,000 won. (5) The property damage from each accident cost 1,017 won, on the average, with regard to the kinds of operation, the highest property damage occurred during transportation work, with the value of 2, 965won.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.249-259
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• 2014

This study has analyzed the factors that influence the safety consciousness of school bus drivers at Child Care Centers. To achieve this, 276 directors and drivers of owner-operator who drives the school bus at Child Care Centers in Chungnam, Chungbuk and Daejeon area were selected as study subjects. For the data analysis, PASW Statistics 18.0 was used. The main results of this study are as follows. The level of safety consciousness of directors and drivers of owner-operator were 6.46 and 6.82 respectively showing that drivers of owner-operator were significantly higher. Second, the factors that influence the safety consciousness were shown to be significantly different for each group. The factors that influence the safety consciousness of directors were shown in the order of whether or not the accident was experienced, safety-seeking motivation, sensation-seeking disposition, safety consciousness of caregivers, perception-motor skill. The factors that influence the safety consciousness of drivers of owner-operator were shown in the order of safety-seeking motivation, health status, daily driving hours, economic status, safety consciousness of caregivers. Based on these results, several ways were suggested to improve the safety consciousness of school bus drivers at Child Care Centers and prevent the traffic accidents.

• The Journal of Korean Academy of Prosthodontics
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• v.24 no.1
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• pp.17-26
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• 1986

The purpose of this study was to investigate true hinge axis location with different times (8:00-9:00 A.M.,2:00-3:00 P.M.) and with experienced and inexperienced groups. 25 subjects, 23-27 years of age , with functionally acceptable occlusion, and no clinical signs of temporomandibular joint dysfunction were participated in this study. In this study arbitrary hinge axis point was located 13 mm anterior to the posterior margin of the tragus on a line from the center of the tragus to the outer canthus of the eye and then the true hinge axis point was located with T.M.J. hinge axis locator. The discrepancies of distance and the direction between true hinge axis point and arbitrary hinge axis point were studied according to times and two groups. The results obtained were as follows : 1. The mean distance from arbitrary hinge axis point to the true hinge axis point on the right and left sides was as follows : Experienced group: linear distance: $1.228{\pm}3.145mm$, vertical distance: $-1.128{\pm}2.515mm$, horizontal distance: $-0.484{\pm}1.806mm$. Inexperience group: linear distance: $1.628{\pm}3.158mm$, vertical distance: $-1.169{\pm}2.090mm$, horizontal distance: $-1.133{\pm}2.367mm$. Horizontal distance between experienced and inexperienced groups was significant statistically. (P<0.1) 2. True hinge axis points located within 5 mm of arbitrary hinge axis point were 86.7% in the experienced group and 84% in the inexperienced group. 3. For experienced operator A with time, the mean distance from arbitrary hinge axis point to true hinge axis point was as follows: Horizontal distance: AM: $-0.613{\pm}1.966mm$, PM: $-0.860{\pm}2.156mm$. Vertical distance: AM: $-0.886{\pm}2.518mm$, PM : $-1.226{\pm}2.660mm$. True hinge axis points had tendency to be located posterior-inferiorly to tragus-canthus line in the afternoon than in the morning, but there was not significant statistically. (P>0.1)

• Journal of Biosystems Engineering
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• v.33 no.3
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• pp.151-156
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• 2008

This study was conducted to evaluate ride vibrations experienced by tractor operators during plowing, rotovating, and transporting operations in Korea. Field data of ride vibrations were taken at the operator-seat interface from 49 tractors and analyzed on the basis of ISO 2631-1 and EU Directive 2002/44. Of the measured ride vibrations 15.4% in the plowing and 12.5% in farm road transport exceeded the 8-hour fatigue decreased proficiency boundary in the fore and aft directions at frequencies from 1 to 5 Hz. 93.9% exceeded the 8-hour potential health risk of ISO 2631-1. The ride vibrations exceeding the 8-hour exposure limit were 38.5% in plowing, 31.6% in rotovating, 100% in farm road transport and 88.9% in concrete road transport. Although most tractor operators were not exposed to ride vibrations greater than the 8-hour exposure limit value (ELV) of EU Directive 2002/44, 7.7% of the operators in the plowing experienced greater vibrations than the ELV in the fore-aft direction. Farm road transport produced greater vibrations than any other operations. Concrete road transport, plowing and rotovating operations followed next. Limit criteria for ride vibration exposure differ depending upon the guidelines. Exposure limit of the health guidance caution zone of ISO 2631-1 is lowest among its kinds.

• Korean Journal of Bronchoesophagology
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• v.8 no.2
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• pp.36-42
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• 2002

Aspirated and ingested foreign bodies continue to present challenges to otolaryngologists. The major discussions were the accurate diagnosis and speedy, safe removal of foreign body. Many diagnostic tools have been tried and removal of foreign bodies has been facilitated by technical improvements with rod lens telescope, video endoscope, flexible fiberoendoscope and safer anesthesia. In spite of these advances, more than 3000 children's death occur per year in the world because of foreign bodies and untold number of parients survive with variable sequelae. In these study, 59 consecutive cases of children and adults with tracheobronchial foreign bodies were reviewed from 1992 to 2001. We studied the history, symptoms, ausculatory radiologic, bronchoscopic finding and post operative complications. 71% (42 cases in 59 cases) of patients had foreign body aspiration history or choking crisis. In 64% (38cases) cough was observed. 81% (48cases) had abnormal finding in chest auscultation and 78% in chest X-ray. Computed tomography was done in 12 cases, all were founded foreign body shadow. Main site of foreign body was right main bronchus (41%, 24cases) and most frequent foreign body was peanut (36% , 21cases) . 4 experienced ICU(intensive care unit) care. 2 cases were failed to remove foreign. In these cases 1 cases was improved by steroid therapy and physical therapy and the other was treated with thoracotomy. We concluded the morbidity and motality were much correlated with speedy decision making and experienced skill of operator.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.3
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• pp.363-371
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• 2021

Forest operations like timber harvesting have already been mechanized to reduce hazards to the worker and increase productivity. However, timber harvesting operations have still been considered potentially dangerous and expensive on steep terrain. Teleoperation, to control the timber harvesting machine at a distance, has the potential to improve the safety, productivity and efficiency of harvesting operations on steep terrain. To verify the effects of teleoperation, an experimental prototype system of a monitor image-based teleoperation was constructed using a real forestry machine. In this study, the productivity of excavator based grapple loader, which is one of the most used mechanized harvesting equipment in the timber production, was analyzed using time-study method. Factors like skill and age of operators, influencing loader productivity in timber loading operation were also evaluated by statistical analysis. Productivity analysis results showed that less experienced operators were more productive than experienced operators for teleoperation through image of monitors in the operator cabin. These results are shown to be unfamiliar to the monitor image and different loading operation pattern by operators. According to the results, the monitor image-based teleoperation system of forestry machine need to improve the resolution and installation position of camera. It was expected that additional studies will be needed for real-time remote control of forestry machine in the future.

• Journal of Drive and Control
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• v.12 no.4
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• pp.28-34
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• 2015

Because heavy-duty construction vehicles such as excavators are required for good engine-room cooling capacity, a hydraulic gear motor is adopted in the cooling fan drive mechanism to actively control the output speed, instead of adopting the conventional ON/OFF type belt drive. While gear motors are normally limited to 140bars of operating pressure, those for the cooling fan are capable of operating at continuous pressures of up to 220bars. After assembly, all gear motors for high pressure must pass an aging test which is a kind of the wearing process between the gear teeth and motor housing. During the aging process with gradual pressure increments, gear sticking sometimes occurs due to abnormal wear, resulting in defects. This paper focuses on a gear-sticking free aging test controller that is designed together with the knowledge of an experienced operator and the analysis results of experimental data of the gear jamming phenomenon. From the aging experiment, it is demonstrated that the developed controller that can alter the setting pressure of the load pump is effective for stabilizing the abrupt increase in the motor input pressure, thus preventing the hydraulic motor from stopping. This is expected to be helpful for the reduction of defects and increase in productivity.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.3
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• pp.70-80
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• 2001

It is necessary to construct an effective regional information system in facing the incoming information intensive society. Many local government in Korea began to recognize a need for constructing a GIS(Geographic Information System) and they are planning to construct GIS´s to improve their administrative efficiency. However, ti requires high-priced hardware, software, and an experienced operator to sue a GIS effectively. The purpose of this study is to develop the GIS program which can be sued with ease by common users. By developing a GIS functioned program using a coordinate recognition module by application of geo-spatial data, and a digital map which is already made, this program can be used efficiently only by only inputting attributes without high-priced hardware and software, and can be utilized easily to every purposes of work with geo-spatial data and attributes. MapObjects, mapping and GIS component, was employed to use geo-spatial data, and Access 97 from Microsoft to manage and attributes database. Visual Basic, objected-oriented language, was used to develop an application program. Results of this study were applied to constructing the Information system of Kanwon National University. This program could be used for various purposed by common users without additional hardware and software.