• The Korean Journal of Pesticide Science
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• v.5 no.4
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• pp.45-49
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• 2001

As a series of studies to develop pest management system for sweet persimmon production matched with the quarantine criterion of sweet persimmon-imported county, a survey was conducted by questionnaire on pest management practice and scheme of increasing income in sweet persimmon farms in Korea. Above 80% of sweet persimmon farmers was over fifties in age. The greatest limiting factor for sweet persimmon production was thought to be disease by the farmers. Percentage of farmers who answered that the most important pest is anthracnose cause by Gloeosporium kaki, and stink bugs was 64.6% and 73.5%, respectively. In particular, the farmers did not consider Dichocrocis punctiferalis, a main targer insect for quarantine in USA, as serious problem. Obtaining information on pest management practice or decision-making on both selection of pesticide and time of pesticide application depended highly on their own experience with the highest proportion. Eight to nine times of pesticide applications a year was highest among farms with 56.6%. More than 80% of farmers recorded the diary of pesticide application. farmers considered increasing cost for pest management as the greatest problem with 35.4% in proportion, and 34.5% of farmers pointed out that increase in export is essential for increasing farm income with highest proportion.

• The Korean Journal of Pesticide Science
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• v.12 no.4
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• pp.414-420
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• 2008

To investigate the actual condition of orchard and pest management of persimmon orchards, a questionnaire was ask to the farmers in major cultivated areas of persimmon and dried persimmon, Sangju, Gyeongbuk in 2007 and 2008. 91.1% of persimmon farmers was over fifties in age and 94.7% of persimmon farmers was cultivated 'Sangjudungshi'. The greatest limiting factor for persimmon production was thought to be disease by the 58.4% of persimmon farmers and the most serious disease was anthracnose by Colletotrichum gloeosporioides. 60.2% of them was answered that the most serious insect pest was scale insects. Obtaining of knowledge or information on pest management depended own experience (37.2%) and 48.7% of answered farmers was decision-marking of pesticides depending on agrochemical market. 54% of persimmon farmers was applied pesticides $3{\sim}5$ times per year. Just 17.7% of them recorded the diary of pesticide application. The greatest problem for management of pest in persimmon orchard was lack of knowledge of pest (60.2%) and farmers considered increasing cost for pest management as the greatest problem with 52.2% in proportion. 66.4% of farmers was mixed cultivation with soybean (37.7%) and hot pepper (26.1%) in persimmon orchard. 44.2% among answered farmers mixed cultivation of persimmon with production of dried persimmon and 54.5% of farmers considered lack of labor as the greatest problem in production of dried persimmon.

• Journal of the Korean Society of Food Culture
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• v.16 no.2
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• pp.147-157
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• 2001

In order to investigate the eating out behavior of university students, this survey was conducted using the questionaires for 710 students(369 male, 341 female) from 11 universities in Seoul. It was revealed that 39.4% of the subjects spent $60,000{\sim}100,000$ won for monthly eating out cost and 57.8% of them ate out more than once a day. Most of them expended less than 3,500 won for lunch, while 36.5% of them spent $4,000 {\sim}5,000$ won for dinner. Dinner was regarded more important than lunch. Korean foods were the most preferred menu for eating out with friends and fast foods were the second. But Boonsik(snack bar foods), Chinese foods and Japanease foods were rarely selected. Frequency of selecting fast foods was 8 times greater than that of Boonsik. This indicates that the preference of western flavor and the pursuit of convenience is getting more obvious. While dating, western foods were preferred, followed by Korean foods, fast foods. The 80 kinds of foods were reported as favored eating out foods. Although 50 among 80 were Korean foods, the rest of them were Koreanized foreign foods most of those were western style. This may suggest that when the students become adults, they will be much fond of western dish for their dinning out. This tendency of preferring western flavor were much apparent in foods for dinner compared with lunch. In both sexes, the standard of food choice was in the order of taste, price, mood, hygiene, service and brand name. But male students were more conscious of price and service while female students were more concerned about taste and hygiene. Most unsatisfying feature in restaurant was unstable atmosphere for both sexes. Taste was the most important sensory factor in selecting the foods, followed by appearance, smell and texture. Major source of restaurant information was recommendation by friends or relatives. But the use of internet or magazine was negligible. Female students had more positive attitude, compared with male students, in using restaurant information and pursuing eating out for gourmet. The dining out menu of which price ranges about $3,000{\sim}5,000$ won could be preferable foods for most people. Therefore, instead of blaming them for eating too much fast foods, new menus which fit the food preference and affordability of the students should be developed.

• Journal of the Korean Institute of Gas
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• v.22 no.4
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• pp.27-31
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• 2018

Classification of explosion hazard areas is very important in terms of cost and safety in the workplace handling flammable materials. This is because the radius of the hazardous area determines whether or not the explosion-proof equipment is installed in the electrical machinery and apparatus. From November 6, 2017, KS C IEC-60079-10-1: 2015 will be issued and applied as a new standard. It is important to understand and apply the difference between the existing standard and the new standard. Leakage coefficients and compression factors were added to the leakage calculation formula, and the formula of evaporation pool leakage, application of leakage ball size, and shape of explosion hazard area were applied. The range of the safety factor K has also been changed. Also, in the radius of the hazardous area, the existing standard applies the number of ventilation to the virtual volume, but the revised standard is calculated by using the leakage characteristic value. In this study, we investigated the differences from existing standards in terms of ventilation and dilution and examined the effect on the radius of the hazard area. Comparisons and analyzes were carried out by applying revised standards to workplaces where existing explosion hazard locations were selected. The results showed that even if the ventilation and dilution were successful, the risk radius was not substantially affected.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.3
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• pp.141-147
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• 2018

In a time when product development cycles are getting shorter and shorter, many companies are making efforts to develop products with high reliability in a short period of time, accelerated life test is widely used as a method to quickly evaluate reliability. Accelerated life test reduces the test life or the life of the product from the observed data by shortening the lifetime of the product or abruptly lowering the performance under the worse condition than the actual condition in order to shorten the test cost or the test time. In this paper, BL3640A-06P+RB35, DC12V model, which is used in the support device of an automatic rotation type digital signage, which display various information such as textures and images on a display screen in a public place or a commercial space, BLDC motors were subjected to a constant stress test and at the rotational speed of 1rpm, $180^{\circ}$ rotation and reverse rotation under actual use conditions, the stress was imposed on the rotating speed of 2rpm and the weight of the actual installed product from 22.2kgf to 10kgf were installed. The lifetime of the actual use environment condition is 23,545 hours and the rotation speed is accelerated. The life time of the acceleration condition with the additional weight is 1,380 hours. The acceleration factor is calculated as 17.06, the one year guarantee test day is 235 days to 14 days, of the period from 470 days to 28 days, and the third year from 704 days to 42 days. The test date of the BLDC motor was tested on the shortened test date, and the rotational speed and the current value were measured. It is found that there is no defect even if it operates as the test date corresponding to the specified one year warranty period and the 3 year accelerated life test which is experimented. Using the statistical technique of the regression analysis the expected time for the motor to defect to #4 samples was 20 years.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.490-497
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• 2018

This study is to identify factors influencing therapeutic diversification strategy for Korean pharmaceutical companies. So, it purposes to find deciding factors for companies to adopt strategy for diversification or specialization. In this paper, we set six factors that are expected to influence diversification. The factors are asset scale, sales, profitability, and growth potential. Also, we included number of employees and SG&A cost ratio as factors that reflect business characteristics. We analyzed the impacts of each factor on diversification and found a relationship amongst each other. In this paper, regression analysis is applied with forward selection method, considering that it takes 5 years for companies to decide on diversification strategy. As a result, asset scale, the number of employees and profitability have significantly influenced decisions of diversification at t-1 time, and growth potential was significantly influenced at t-2 time. Korean pharmaceutical companies generally tend to go with specialization model if they have larger asset scale, higher profitability and growth potential. However, they have tendency to decide on diversification strategy, if they have large number of employees. Overall, the result of this study is expected to provide useful information for Korean pharmaceutical companies to set the suitable strategy for their situation to become a competitive company in global pharmaceutical market.

• Environmental and Resource Economics Review
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• v.27 no.2
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• pp.261-286
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• 2018

This paper evaluated the economic feasibility of the life extension of Kori unit 1 and Wolsong unit 1 according to the types of the nuclear power plants (NPPs) and the life extension period comparing to the levelized costs of energy (LCOE) of the new NPPs, coal-fired plants (CFPs), and combined cycle gas turbine (CCGTs) which proposed in the $7^{th}$ Basic Plan for Electricity Supply and Demand. The economic feasibility of the life extension of NPPs using LCOE method is affected by the types of NPPs, lifetime extension periods, discount rate, and capacity factor. According to the analysis results, the pressurized light water reactor (PWR) is more economical than the pressurized heavy water reactor (PHWR). Comparing the economical efficiency between the life extension of NPPs and other alternatives, the operation of the PWR for 20 years is more economical than the one of new NPPs and CFPs. However, 20 years of life extension of PHWR is more economical than the CCGTs, but less economical than new NPPs and CFPs. In summary, the 20 years of life extension of the NPPs seems to be more, especially for the PWR, which is more cost effective than other generation alternatives. Therefore, the government policy of the life extension of NPPs need to be a selective approach that simultaneously considers both safety and economics rather than closing all NPPs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.644-652
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• 2018

This paper describes the conceptual design of a customized gripper for the assembly process of IT products, which has a relatively short and regular product replacement cycle. The grippers that are used in the manufacturing field are mostly composed of one to two degrees of freedom and they can only handle one object, not multiple ones. Cost is also an important factor. If it were possible to develop a gripper suitable for the assembly process quickly and easily, some of the difficulties involved in its automation caused by the frequent changes of product and process could be solved. The assembly process utilized for this research is defined and described as the procedure and method of the process analysis due to the confidentiality of the manufacturer. We used an axiomatic design to derive the functional requirements and design parameters of the gripper used for the tablet PC assembly process. We proposed a design method for the conceptual design of the gripper by determining these parameters. For the feasibility study, a specific process was selected and the progress of the gripper design was described as an example. Although there have been studies on the design guidelines for grippers, their considerations are too general and their degree of freedom is too high. This paper defines the function of the gripper based on the assembly process of the IT products, which allows their production to be streamlined and automated. In this research, we attempted to produce a design that reflects the assembly process, not just one that enables objects to be held.

• Journal of Korea Port Economic Association
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• v.29 no.4
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• pp.1-25
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• 2013

The purpose of this paper is to estimate economic benefits for the investment of railway transshipment system with non-powered turntable. The freight transport by railway can have decided advantages over trucks in terms of energy efficiency, emissions and cost for certain freight movements, just as transportation in the metropolitan region can have great advantages over driving truck. But the freight transport by truck should gain significant mobility benefits from a freight railway system. Thus, the railway transshipment system with non-powered turntable which is coupled railway transport advantages with load transport advantages has been developed and used in the european countries. This research has conducted the empirical analysis, by calculating the investment of railway transshipment system with non-powered turntable. The key factor for the economic benefits for the non-powered turntable is the utilizing throughputs. This demand is influenced by the throughput in the railway transshipment system. The main results of this paper are as follows: railway transshipment system with non-powered turntable does not have economic benefit for investment. We recommend that the plan for investment has to be considered the modification.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.145-160
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• 2018

Long subsea tunnel is subject to many restrictions in terms of spatial limitation when vertical or inclined shafts are built for tunnel ventilation. So, the construction of some artificial island is required to provide ventilation. But, because of construction difficulty and cost increase, it is necessary to minimize the artificial island construction. As a result, ventilation distance become longer and supply airflow becomes excessive due to air leakage, So, duct mounting for temporary ventilation is impossible or fan pressure and power increase exponentially. Therefore, in order to build a long subsea tunnel, it is necessary to overcome these practical problems and to develop technical solution that can keep the comfortable condition of tunnel environment during construction. In previous study, we have found that air leakage is the key factor in solving these problems and experimental results show that the new connection method has a leakage rate of about $1.46mm^2/m^2$ (Jo et al., 2017). In this study, we present the experimental results of the measurement of the leakage rate of the prototype with the new connection method, and analyze experimentally the improvement of the leakage rate when applying the flexible cover inside the duct to improve the leakage performance of the existing connection method.