• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.231-240
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• 2006

This study conducts a questionnaire survey of 492 middle school students in Jeju islands about the rate of using glasses/contact lens, the place and time of visual acuity test, the period of changing the glasses, the purchase price, the mason to change the glasses, the interrelationship between wearing spectacles and residential district, etc. The results are as follows: 1. 45.33% of the object of investigation use the glasses or contact lens to correct their visual acuity. Among them, the student who wears only glasses is 93.27%, the student who wears glasses and contact lens together is 5.83%, the student who wears only contact lens is 0.90%. 2. As for the period of changing his(her) glasses, below 6 month is 20.18%, from 6 month to one year is 52.02%, from one year to two years is 20.18% and more than two years is 7.62%. 3. As for the purchase price to change his(her) glasses, below 30,000won is 13.45%, from 30,000won to 50,000won is 43.50%, from 50,000won to 70,000won is 23.77%, from 70,000won to 100,000won is 15.25% and more than 100,000won is 4.03%. 4. As for the reason of changing his(her) glasses, cause of change of visual acuity is 55.16%, by broken frame and lens is 27.35%, as want to just change his(her) spectacles is 14.80% and as the others is 2.69%. 5. As for the relative importance in purchasing glasses, the student who thinks more frame is 16.59%, the student who thinks more lens is 67% and the student who thinks both frame and lens is 58.74%. 6. As for the frist time of visual acuity test, 1 grade of elementary school is 37.2%, 3 grade of elementary school is 12.56%, 4 grade of elementary school is 11.66% and 6 grade of elementary school is 11.66%. 7. As for the place of visual acuity test to determine the Dptr. of glasses which wear now, opitican's shop is 57.85% and ophthalmic clinic is 42.15%. 8. As for the frist time of wearing the glasses or contact lens for correct his(her) visual acuity, the most of answer(21.97%) is at 6 grade of elementary school. 9. As for the reason why does not wear the glasses or contact lens though his(her) naked binocular vision is below 0.8, as does not feel any difficulty in daily life is 62.5%, as know that the more wear, the more decrease his(her) visual acuity is 15.65%, by economical circumstance is 6.24% and as not good externally is 15.63%, respectively.

• Journal of Biosystems Engineering
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• v.33 no.6
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• pp.390-395
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• 2008

Current high oil price and the agreement on global climate change prevention have increased worldwide investment and research on renewable energy. In Korea, development of a rapeseed dryer for bio-diesel production has been started in 2007. Usually, rapeseeds are harvested in early summer, because rice cultivation is followed right after rapeseed harvesting. Early harvest and bad summer results in highly moistured rapeseed and development of artificial drying system is required to dry great amount of rapeseed that couldn't be processed by sun drying alone. The rapeseed dryer was modified from an existing circulation type grain dryer. Modification of the dryer was performed with the aid of CFD simulation. Drying test showed that drying rate of rapeseed was 1.51%/h and germination rate reduction was 4.5%p for the drying temperature of $60^{\circ}C$.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.4
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• pp.624-632
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• 2008

This study was conducted to estimate the drift of change for in Kimchi purchases, and to contribute to the efforts to improve the quality improvement of Kimchi sold at markets. Questionnaires were distributed to 450 adults, and 396 samples were statistically analyzed. There were significant differences in the average values of importance and satisfaction. Based on analyses of the 14 factors, the level of satisfaction was significantly lower than the level of importance. Importance-factors such as 'taste' ($4.56{\pm}0.81$) and consistency of 'quality' ($4.37{\pm}0.79$) are very important to consumers, whereas 'package volume' ($3.79{\pm}0.91$) and 'price cutting' ($3.84{\pm}1.01$) are rarely considered by consumers. Fourteen significance factors were three factors. Overall significance for selection attributes when purchasing Kimchi differed according to gender, age and marital status. Fourteen satisfaction factors were extracted to four factors. Overall satisfaction for selection attributes when purchasing Kimchi differed according to martrial status. Total satisfaction with selection attributes when purchasing the food was greatly affected by its quality and packaging. These findings confirmed that Kimchi products should be diversified and active marketing should be carried out if Kimchi is to become a global product.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.3
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• pp.58-63
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• 2009

The global restriction on pollutant emissions and the soaring of crude oil price are expected to result in the change of future transportation system. Hydrogen is considered to be the leading candidate as an alternative energy source before other new alternative energy sources emerge. Scientists anticipate that hydrogen fuel gas turbine engine and fuel cell will be the power plant of the aircraft in the near future. To realize the aircraft powered by fuel cell system in the future, the technologies such as fuel cell with higher energy density, compressed gas or liquid storage system of hydrogen fuel, and efficient and lightweight electric motor have to be developed first.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.864-871
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• 2002

Acoustic emission(AE) technique has been applied to not only mechanical property testing but also on-line monitoring of the entire structure or a limit zone only. Although several AE devices have already been developed for on-line monitoring, the price of these systems is very high and it is difficult for the field to apply yet. In this study, we developed a specially designed PC-based leak detection system using A/D board. In this paper, AE technique has been applied to detect leak for heat exchanger by analyzing the characteristics of signal obtained from leak. It was confirmed that the characteristics of the signal generated by the turbulence of gas in the heat exchanger is narrow band signal having between 130-250kHz. Generally, the amplitude of leak signal is increased as the leak size increasing, but showed no significant change at frequency characteristic. Leak source location can be found by determining for the paint of highest signal amplitude by comparing with several fixed sensors. In this paper, AE results are compared with the PC-based leak detection system using A/D board.

• The Journal of Sustainable Design and Educational Environment Research
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• v.9 no.1
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• pp.11-22
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• 2010

Recently, the necessity of open spaces is increased greatly in the city. But in many reasons, open spaces are diminishing gradually in the existing cities. It is more difficult to keep that space because of expensive land price, and the interests between the neighbors. To solve this problem, the local governments tries to change the street system more convenient to the pedestrian by adapting no vechile street system during some specific time. In this point of view, the street which include fence of school, house, and apartment can be the open space. Especially, removal of the school fence can be a useful solution providing open spaces to small cities suffering from lack of open spaces. In this researching background, several schools in Wonju were selected in this research, some has already been opened, and others yet. Opinions of students, presidents of these schools, and citizens are surveyed about removal of fence. In the basis of this result, we deduce problems followed by removing the fence, and reflect it in the plan of opening the fence to present the guidance to cross over the functional limitation of the fence and use it as a open space.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.75.1-75.1
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• 2010

This research presents a fuel cell simulator for control logic verification and operator training. Nowadays, power industries are focusing on clean energy as a response to new policy. The fuel cell can be the solution for clean energy, but operating technology is not well developed compared to other conventional power plans because of its short history. Therefore we need a simulator to verify the new control strategy and train operators, because the price of a real fuel cell system is too high and mechanically weak to be used for these kind of purposes. To develop the simulator, a 300 KW MCFC(Molten Carbonate Fuel Cell) system was modeled with stack, BOPs(pre-reformer, steam generator, etc) and mechanical components(valves, pipes, pumps, blowers, etc). The process model was integrated to emulated control system and HMI(Human Machine Interface). A static load and open loop tests were conducted for verifying the accuracy of the process model, since it is the most important part in the simulation. After verifying the process model, an automatic load change and start-up tests were conducted to verify the performance of a new control strategy(logic and functional loops).

• The Journal of Fisheries Business Administration
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• v.48 no.3
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• pp.61-74
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• 2017

This study is aimed to analyze the change of chinese fishing vessels' entry into the East Sea off North Korea and suggest directions for countermeasures. Based on the real landing data in China, Chinese fishing vessels' squid catch volume and value in the East Sea off North Korea are estimated. Results show that at least 205 thousand tons of squid was caught by Chinese fishing vessels in 2014. If the catch amount is calculated by the unit price per kilogram at the same year in Korea, it would be 556.3 billion KRW. As the UN sanctions become stricter with the recent resolution 2371 passed, Chinese fishing vessels' entry may increase in the future to compensate decreased seafood supply from North Korea. Even though there are not many options left for Korea to decrease the impact of Chinese depletive fishing, the study suggests countermeasures such as strengthening cooperative crack down on the Chinese illegal fishing vessels in Korean waters; increasing cooperation with UN member countries to incorporate banning the trade of fishing rights in the next UN sanctions; establishing regional fisheries management organization and managing migratory species with China and Japan cooperatively in the long term.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.114-120
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• 2010

Optimization of the turning process has been concentrated on the selection of the optimal cutting parameters, such as cutting speed, feed rate and depth of cut. However, optimization of the cutting parameters does not necessarily guarantee the maximum profit. For the maximization of the profit, parameters other than cutting parameters have to be taken care of. In this study, 8 price-related parameters were considered to maximize the profit of the product. Regression equations obtained from RSM technique to relate the cutting parameters and maximum cutting volume with a given insert were used. The experiments with four combinations of cutting inserts and material were executed to compare the results that made the profit and cutting volume maximized. The results showed that the cutting parameters for volume and profit maximization were totally different. Contrary to our intuition, global optimization was achieved when the number of inserts change was larger than those for volume maximization. It is attributed to the faster cutting velocity, which decreases processing time and increasing the number of tool used and the total tool changing time.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.59
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• pp.63-73
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• 2006

Auctions have been traditionally used to find the current price of goods when little is known about their true value. A special auction methodology, called a 'simultaneous multiple round auction', is available to auction radiofrequency spectrum where all lots are simultaneously on of for over multiple rounds of bidding. This type of auction is especially useful when there are lots that are of essentially equal value and substitutable, except that different bidders may prefer different combinations of lots. By using multiple rounds, a bidder has the opportunity to gather information concerning the value of individual lots and can change strategy by shifting the bidding to another preferred combination if one combination becomes too expensive. Information is released in three main ways during an auction: Bidder Status; High Bids; and Bandwidth Value.