• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.31-39
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• 1999

A good atomization in uniform size brings the elevation of thermal efficiency in spray combustion, the beautiful painting on surfaces, and the economical sprinkling of chemicals. Ultrasonic atomization has been expected as a good uniform atomization mechanism due to its uniform size distribution. Influx, load, and physical properties of liquids are the effecting factors to atomize liquids. In this study, distilled water and city water are selected as reference liquids and gasoline, kerosene, and petroleum as fuel liquids. Characteristics and affinity to get the maximum effect for the ultrasonic atomization are observed by using the two ultrasonic transducers with 28kHz and 2MHz. Results show that the size distributions of liquid spray dorplet by the direct vibration method prevail over those by the aerosol method in uniform droplet size and as a whole, sizes of spray liquid droplets are increased slightly according to increasing influx in the direct vibration method and quantities of spray droplets in the aerosol method decreasing according to increasing liquid load h.

• The Korean Journal of Health Service Management
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• v.9 no.4
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• pp.79-90
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• 2015

Objectives : The aim of this study was to investigate the effect of musculoskeletal symptoms and job stress on the fatigability of 268 dental health care workers in Busan. Methods : A structured, self-administered questionnaire was given from Oct 1 through Oct 10, 2015. The collected data were analyzed with the SPSS 18.0 program. Results : The results were as follows. First, for musculoskeletal symptoms, job stress and fatigability, the highest scores were for low back pain (3.23), business stress (2.95) and physical fatigability (3.32), respectively. Second, physical fatigability increased with increasing myofascial pain syndrome, low back pain and business stress. Mental fatigability increased with increasing business stress, human relationships and social activities and decreasing age. Conclusions : Taking the above into consideration, this thesis suggests that there is definite influence from musculoskeletal symptoms and job stress factors on physical and mental fatigability.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.4
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• pp.249-262
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• 2009

HSDPA(High Speed Downlink Packet Access) service has begun nationwide network service since the year 2007 and will be leading technology in mobile service technologies in domestic. But the ARPU(Average Revenue Per Use) from HSDPA has not increased, despite of increasing in subscribers with HSDPA service. It's important to understand why the incresing subscriber with hsdp didn't cause the increasing of its usage. The purpose of this study is to examine factors affecting the intention to adopt and to use HSDPA which refer to the new 3.5 generation communication service, and we are to analyze the relation between the two intentions based on previous studies about technology acceptance.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.3
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• pp.351-364
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• 1996

This paper presents on EMQ model which determines an optimal production run length in a deteriorating machine. It is assumed that a machine is subject to a random deterioration from an in-control state to an out-of-control state with on arbitrary distribution and thus producing some proportion of defective items. An optimal production run length and a minimum average cost are derived in each of three deteriorating processes; constant, linearly increasing, and exponentially increasing. The model with repair cost is also analyzed. Several mistakes in previous research are found and discussed. Numerical experiments are carried out to see the behavior of the proposed model depending on the cost factors as well as machine parameters, and some interesting behaviors are observed.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.6-8
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• 2005

The plunger speed of solenoid actuator is affected by mass of plunger, magnetic motive force, inductance, and return spring. These factors are not independent but related with each other according to design characteristics of solenoid actuator. So, it is impossible to change the designed value for the purpose of increasing plunger speed. In this study, we have analyzed the characteristics of high-speed solenoid actuator having a non-magnetic ring which plays a role to concentrate the effective magnetic flux into plunger. For more detailed analysis, we have performed FEM analysis and decided the optimal attaching position and length on the guide tube based on these results. And, we proved the propriety of the non-magnetic ring effect by experiments.

• Proceedings of KOSOMES biannual meeting
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• 2001.05a
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• pp.105-133
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• 2001

World trade has been increasing continuously in total volume, on the other hand, environmental protection on sea and conservation of fishery resources has been rising up the major issue. All of the world are pushing their efforts two major purposes to the full, one is taking competitive place in marine transportation throughout the world and another Is environment protection. Pusan Port as world leading Port put its all effort in bring more ocean going vessels and securing their traffic route by providing them more information related marine traffics through PTMS in port. During two years of operation, statistics of marine traffic accidents showed that many dynamic casualties such as collisions, groundings, and rammings has been decreased. However, due to increasing cargo volume, limited water area and unpredictable weather condition, potential risks still exist high. In this paper, in order to maximize the efficiency of PTMS and reduce various risks in the future, we examine risk factors over operational results and experience, and propose reasonable operational methods of PTMS.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.409-424
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• 1987

Simulation on the hot water ONDOL heating system was made in order to investigate the variation of room temperature and specific fuel consumption of boiler. Heat balance equation was derived by response factors and solved implicitly. Variation of room temperature and specific fuel consumption of boiler were calculated with respect to the thickness of room floor, the absorptivity of wall for solar radiation, on-off temperature range of boiler and air exchange. The results show that specific fuel consumption of boiler is independent of the thickness of room floor and decreases with increasing the absorptivity of wall and on-off temperature range of boiler. However, it increases with increasing the air exchange. They also show that, when the absorptivity and on-off temperature range of boiler are increased, the amplitudes of room temperature variation increase.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2005.11a
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• pp.371-374
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• 2005

As the aging of this society, instead of growing numbers old protective functions of families decreased according to increasing tendency of nuclear families, increasing rates of females' participation of economic activities. Now, the problem of supporting the old is in need of social supporting system the cope with this are based on these factors are like this: 1) It is necessarily the instruction of medical welfare service. 2) The overlapped service is avoided and the service of specialized. 3) Most of the welfare service institution is Seoul and local city hall, so it needs the institution is transferred. 4) It needs the increase the number of home helper. 5) When the service is offered, the government must considers finance, elderly health condition and preference. 6) It needs the department for the welfare service for the old who stay at home.

• The Journal of the Korean dental association
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• v.49 no.10
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• pp.599-608
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• 2011

Dentist-patient communication has long been recognized as an important part of dental care. It has many positive outcomes, including reducing patient dental anxiety and increasing patient satisfaction and patient compliance. Above all, the need to communicate through conversation with dentist must be perceived as a basic dental patient's need for good clinical outcomes. In the future, increasing geriatric dental patients will pose challenges to dental profession. Factors influencing dentist-geriatric patient communication should be researched and relevant techniques should be shared among dentists.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1309-1311
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• 2005

The operating speed of PWM controlled high speed magnet is affected by mass of plunger magnetic motive force inductance and return spring It is impossible to change the value of them for the purpose of increasing the speed because these factors are related with each other This paper introduces a speed increasing method using a non magnetic ring which is welded in the middle of magnetic guide tube and also presents the characteristic equations results of FEM analysis for magnetic flux distribution and computer simulation results for the dynamic characteristics of plunger motion And we proved the effect of non magnetic ring by experiments using a prototype