• Journal of Magnetics
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• v.17 no.1
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• pp.42-45
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• 2012

We have developed an alternating magnetic field stimulation system consisting of a switched-mode power supply and a digital control circuit which modulates a duty ratio to maintain a magnetic field intensity of a few mT even while the frequency increases up to 4 kHz with a controllable coil temperature below $30^{\circ}C$ in air. This duty ratio modulation and water circulation are advantageous for cell culture under ac-magnetic field stimulation by preventing the incubator from exceeding a cell-viable temperature of $37^{\circ}C$. Although the temperature of the coil when subjected to a sinusoidal voltage rapidly increased, that of our system modulated by the duty factor did not change. This is a potentially valuable method to investigate the effects of intermediate frequency magnetic field stimulation on biological entities such as cells, tissues and organs.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.1-7
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• 2023

TCP is considered a major candidate transport protocol even for constrained IoT networks due to its ability to integrate into the existing network infrastructures. Since TCP implementations such as uIP TCP often allow only a single TCP segment per connection to be unacknowledged at any given time due to resource constraints, the congestion control relies only on RTO management. In our previous work, to address the problem that uIP TCP performs poorly particularly when a radio duty cycling mechanism is enabled and the hidden terminal problem is severe, we proposed a RTO scheme for uIP TCP and validated the performance through Cooja simulation. In this study, we investigate the effect of other factors that were not considered in our previous work. More specifically, the effect of traffic intensity, the degree of the hidden terminal problem, and RDC is investigated by varying the offered load and the transmission range, and the RDC channel check rate. Simulation results imply that we need to further investigate how to improve TCP performance when the radio duty cycling mechanism is used.

• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.171-177
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• 2019

Smart farm is a breakthrough technology that can maximize crop productivity and economy through efficient utilization of space regardless of external environmental factors. This study was conducted to investigate the optimal growth and physiological conditions of Chinese matrimony vine (Lycium chinense) with LED light sources in a smart farm. The light source was composed of red+blue and red+blue+white mixed light using a LED system. In the red+blue mixed light, red and blue colored LEDs were mixed at ratios of 1:1, 2:1, 5:1, and 10:1, with duty ratios varied to 100%, 99%, and 97%. The experimental results showed that the photosynthetic rate according to the types of light sources did not show statistically significant differences. Meanwhile, the photosynthetic rate according to the mixed ratio of the red and the blue light was highest with the red light and blue LED ratio of 1:1 while the water use efficiency was highest with the red and blue LED ratio of 2:1. The photosynthetic rate according to duty ratio was highest with the duty ratio of 99% under the mixed light condition of red+blue+white whereas the water use efficiency was highest with the duty ratio of 97% under the mixed light of red+blue LED. The results indicate that the light source and light quality for the optimal growth of Lycium chinense in the smart farm using the LED system are the mixed light of red+blue (1:1) and the duty ratio of 97%.

• Journal of Korean Academy of Nursing
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• v.40 no.1
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• pp.43-51
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• 2010

Purpose: The purpose of this study was to investigate sleep habits, sleep disturbance, and circadian types, and to identify factors influencing sleep disturbance in nursing students. Methods: Participants were 140 senior nursing students. The data were collected from May 19 to 27, 2008 using self-report questionnaires. Results: 1) Evening type delayed sleep-wake schedules were more frequent than for morning type, especially during weekend and evening shift duty. 2) In total sleep time, there were no significant statistical differences between morning type and evening type during weekdays, weekend, day or evening shift duty. 3) On weekdays and day shift duty, the mean score for sleep disturbance was significantly higher in the evening type compared to the morning type. 4) Sleep disturbance in weekday and day shift duty was influenced by circadian types, eating habits, and gender. Conclusion: The circadian types are a very important factor for determining the sleep quantity and quality in nursing students.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1095-1100
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• 2006

An experimental study has been performed to investigate the correlation on compressor discharge temperature of system A/C in heating mode. Indoor and outdoor temperatures, the heating capacity, compressor discharge temperature and loading time are measured by the psychrometric calorimeter. The system is controlled by applying the scroll compressor, which Is operated by PWM valve and loading duty. With increasing outdoor temperature, the heating capacity increases, With increasing indoor temperature, it decreases. Also, with increasing loading duty the heating capacity increases. According to the increase in outdoor temperature and loading duty, compressor discharge temperature increases. From these experimental data, the correlation on compressor discharge temperature is proposed. It is expressed as a function of indoor temperature, outdoor temperature, and loading duty. The correlation obtained from the present study is agreed with the experimental data within $2^{\circ}C$.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.75-86
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• 2005

To investigate the fatigue characteristic of upper limbs, this study analyzed RMS(root mean square) and MPF(mean power frequency) value between initial and terminal stages of each experiment condition. And the effect of intermittent endurance time was evaluated using the Borg's CR10 value that was measured for the parts of upper limb. According to the results of ANOVA on RMS value, there were significant difference on the %MVC about push, pull, and down force exertion. Particularly the ANOVA of up force exertion was significant difference on shoulder flexion, elbow flexion and rest time as well as %MVC. The results of ANOVA for MPF value were significant difference on the %MVC in regard of the push and up force exertion. In case of up force exertion, MPF value tended to shift low frequency at all of the experiment conditions. According to the analysis of duty cycle, RMS value considerably increased over 50% duty cycle and as the %MVC increased, the duty cycle affected the increase of RMS value. MPF value for up and down force exertion decreased at 33%, 50% and 67% duty cycle for all of %MVC. Borg CR10 value of hand and forearm were below the 3-point to the 40% of endurance time at 30%MVC and to the 20% of endurance time at 50%MVC with the exception of up force exertion. But Borg CR10 values of upper arm and shoulder at up force exertion were more than 3-point to the 20% of endurance time at 30%MVC and in the start point of endurance time at 50%MVC.

• Fashion & Textile Research Journal
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• v.13 no.4
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• pp.572-581
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• 2011

The purpose of this study was to investigate the effect of duty free shop consumers' store benefits sought and fashion merchandise shopping orientation on store satisfaction. Survey data were collected from questionnaires filled out by 194 domestic consumers who had purchase experience of fashion goods in duty free shops located in Korea. The data were analyzed by reliability analysis, factor analysis, and multiple regression analysis. The results of this study were as follows: First, the store benefits sought was categorized into five factors such as pursuit of convenience, salesperson/atmosphere, promotion, product quality, and product fashionability/variety. The fashion merchandise shopping orientation was categorized into six factors such as pleasure orientation, pursuit of fashion, pursuit of brand, planned orientation, pursuit of confidence, and convenience orientation. The store satisfaction was categorized into six factors such as atmosphere/reputation of store, promotion, product fashionability/variety, convenience, price, and salesperson. Second, the store benefits sought, composed of pursuit of convenience, salesperson/atmosphere, promotion, product quality, and product fashionability/variety, had an effect on the store satisfaction. Third, the shopping orientation such as pleasure orientation, pursuit of fashion, pursuit of brand, and planned orientation, with the exception of pursuit of confidence and convenience orientation, had an effect on the store satisfaction.

• Journal of Korean society of Dental Hygiene
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• v.15 no.5
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• pp.907-915
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• 2015

Objective: The purpose of the study is to investigate the curriculum development and operation based on national competency standard (NCS). Methods: The duty of the dental hygienist was analyzed based on DACUM by ten experts in January, 2011. The duty model of the dental hygienist was inspected after duty analysis. The subjects of choice were preventive dentistry and practice. The satisfaction with the subjects were carried out from March to June, 2015. Results: The duty analysis of dental hygienist by DACUM produced preventive dental treatment(11 tasks), oral health education(3 tasks), comprehensive dental hygiene treatment(6 tasks) and 12 categories(156 tasks). Preventive dental treatment was divided into preventive dentistry and practice, oral health education was changed into oral health education and practice, and comprehensive dental hygiene treatment was replace by comprehensive dental hygiene and practice. The contents of preventive dentistry and practice included outline, learning objective, related knowledge and self evaluation. Professional evaluation required mutual experience and evaluation of the students. The mutual evaluation of the students was $4.61{\pm}0.506$(dental plaque control) and $1.80{\pm}0.316$(tooth brushing). The professional evaluation was $1.73{\pm}0.274$(dental plaque control) and $1.60{\pm}0.322$(tooth brushing)(p<0.01). The satisfaction with preventive dentistry and practice was $4.61{\pm}0.506$(improvement in practical work ability), $4.58{\pm}0.511$(knowledge improvement) and $4.55{\pm}0.572$(NCS educational environment) in order. Conclusions: The operation of NCS curriculum is considered to improve practical work ability and to solve skill mismatch between dental industries and educational training institutions.

• Journal of Korean society of Dental Hygiene
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• v.14 no.4
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• pp.453-462
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• 2014

Objectives : The purpose of the study is to investigate the education, certification system, and extent of duty of dental hygienist between Korea and five developed countries including United States, Canada, England, Australia, and Japan. Methods : Internet based access to five developed countries was made and the analysis was done for the definition of occupation, main duties, similar occupations, education policy, job descriptions, license certification system, standards of duty, Q & A management, current status of obtaining certification, and scope of work. Results : United States has a two-year associate degree(AS) and a four-year bachelor degree(BS). Canada has two to three years degree and a two-year course is accepted in england and Australia. In the meanwhile, Korea and Japan have two-year and four-year educational courses. The duty of dental hygienists includes the prevention education for dental health and continuing dental health care. Most of the dental hygienists in Korea and Japan play the assistant roles for the dental surgeons. United States has national board examinations including written examinations, practical examinations, and computer assisted examination. Written and practical examinations are also conducted in Korea. England and Australia have the recognized educational organizations for qualification. Conclusions : Problem based and problem solving skills are the most important in dental hygienist education in Korea. The training of highly competent dental hygienists must be done for the improvement of dental hygiene in Korea in the near future.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.53
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• pp.207-229
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• 2012

In IP 7 and LCCP 201, Law Commission considers the insured's duty of good faith after the formation of the contract. This article intends to review and analyse the legal implications of proposals in IP 7 and LCCP 201. The results of analysis are following. First, Law Commission propose to end the remedy of avoidance under MIA 1906 section 17, because avoidance of past claims is unprincipled, impractical and unnecessarily harsh. Secondly, LC proposes that an insured who makes a fraudulent claim should forfeit the whole claim which the fraud relates, but that the fraud should not invalidate previous and legitimate claims. Thirdly, LC proposes to introduce a statutory right for the insurer to claim damages for the reasonable, foreseeable costs of investigate a fraudulent claim in specific circumstances and that damages would be limited to those cases where the insurer can show an actual, net loss. Finally, LC provisionally propose that an express fraud clause should be upheld in business insurance, whereas in consumer insurance, any term which purports to give the insurer greater rights in relation to fraudulent claims that those set out in statute would be of no effect.