• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.89-99
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• 2006

The PCRW (Precast Concrete Retaining Wall) has many advantages compared with cast in place concrete retaining wall : shorter construction period, excellency of quality and minimum interference with the adjacent structure and traffics. However, shallow foundation type of PCRW, which has comparatively better ground condition, has some disadvantages such as difficulty in transportation and higher cost due to the size of PCRW being expanded by resisting only with self-weight if there is no other supplementary reinforcement. The presented study, in order to complement such disadvantages of PCRW, have applied the micropile method. The micropile method has advantages like low-cost and high-efficiency and does not require huge space, because it can be executed with small size equipment. However, the mechanical behavior characteristics of the PCRW reinforced by micropile, which is installed to improve the reinforcement effect, is not yet clearly identified and there is no suggested standard as to the length, diameter, install angle and install position of micropiles. Hence, this method is yet being designed depend on engineer's experience. In this study, various laboratory model tests as to sliding and overturning were performed in order to identify and present the optimum type of reinforcement and reinforcement effect of the PCRW reinforced by micropiles. In addition, it also executed numerical analysis for the purpose of verifying the optimum type of reinforcement for micropiles based on the results of laboratory model tests. The optimum reinforcement type of micropiles was estimated by model test and numerical analysis. The length of micropiles is 0.4 times wall height and the diameter is 0.04 times wall length.

• The Korean Journal of Zoology
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• v.22 no.2
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• pp.55-66
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• 1979

Drosophila melanogaster Oregon-R had been bred in a large quantity and the crude alcohol dehydrogenase (ADH) obtained was purified and the activity of the enzyme was measured, analyzed and its patterns were examined. The results obtained are presented below: 1. Through this experiment, it was found that the specific activity of ADH of the D. melanogaster is about more than five times as strong as that of the D. mlanogaster Samarkands which was found by Jacobson et al. in 1970. 2. It was learned that the ADH isozyme patterns of this strain was found to be $ADH_1$ and $AHD_2$ in the fast form and $ADH_5$ in the slow form. 3. It was learned that, $ADH_1, ADH_2$, and $ADH_5A$ are found as the ADH patterns of crude enzyme, and that $ADH_1, ADH_5A$ and $ADH_5B$ as the ADH patterns of the purified enzyme. 4. After the isolation andpurification of $ADH_5A$ and $ADH_1$ isozymes, specfic activity of $ADH_5A$ was found to be 4,330 (units/mg) and that of $ADH_1$ to be 3,670 (units/mg), and the exact position of their zymogram on the 7% acrylamide disc gel was distinguished.

• Journal of Korean Society of Forest Science
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• v.113 no.2
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• pp.259-270
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• 2024

Since 2013, Korea has allocated significant budgets and manpower nationwide to prevent the spread of pine wilt disease and to reduce damage. As a result, the number of damaged trees decreased from 2.18 million in 2014 to 310,000 in 2021. However, the damage has increased again since then. Despite the overall decrease in the number of damaged trees, the scope of the damage continues to expand every year. Previous studies have develope In order to judge the control performance, a quantitative control performance analysis method to objectively evaluate control performance. This method takes into consideration two factors-quantity change and the change in the damage area, which is an area factor. This approach provides a more comprehensive assessment than the control guidelines that only suggest changes in damage grade based on the volume of damaged trees. The expansion of the damage range is also an important factor in analyzing control performance, but previous studies have not reflected this. Therefore, this study calculates the change in the distance of the pine wilt disease boundary area for Gyeongsangbuk-do, where changes in the damage range can easily be observed from year to year. The study then creates application criteria and coefficients and uses them to improves control performance index calculation formula. As a result, it was possible to calculate a quantitative analysis of the control performance, taking into account the changes in the damage range. When the improved formula was applied to 26 cities, counties, and districts in Gyeongsangbuk-do, it slightly decreased or increased compared to the existing calculation formula. This confirmed that the control performance index can change from a positive value (+), indicating increased damage, to a negative value (-), indicating reduced damage.

• Radiation Oncology Journal
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• v.23 no.3
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• pp.186-193
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• 2005

Purpose: To improve the management of a medical linear accelerator, the records of operational failures of a Varian CL2l00C over a ten year period were retrospectively analyzed. Materials and Methods: The failures were classified according to the involved functional subunits, with each class rated Into one of three levels depending on the operational conditions. The relationships between the failure rate and working ratio and between the failure rate and outside temperature were investigated. In addition, the average life time of the main part and the operating efficiency over the last 4 years were analyzed. Results: Among the recorded failures (total 587 failures), the most frequent failure was observed in the parts related with the collimation system, including the monitor chamber, which accounted for $20\%$ of all failures. With regard to the operational conditions, 2nd level of failures, which temporally interrupted treatments, were the most frequent. Third level of failures, which interrupted treatment for more than several hours, were mostly caused by the accelerating subunit. The number of failures was increased with number of treatments and operating time. The average life-times of the Klystron and Thyratron became shorter as the working ratio increased, and were 42 and $83\%$ of the expected values, respectively. The operating efficiency was maintained at $95\%$ or higher, but this value slightly decreased. There was no significant correlation between the number of failures and the outside temperature. Conclusion: The maintenance of detailed equipment problems and failures records over a long period of time can provide good knowledge of equipment function as well as the capability of predicting future failure. Wore rigorous equipment maintenance Is required for old medical linear accelerators for the advanced avoidance of serious failure and to improve the qualify of patient treatment.

• Journal of Fisheries and Marine Sciences Education
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• v.14 no.2
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• pp.229-248
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• 2002

The primary objective of this study is to firstly survey and analyze the working environment and actual condition, secondly know their problems, and then provide the basic data about how to improve their working conditions. The specific study items for getting the goal above is as follows: 1. How does the industrial company connect with highschool vocational education well? 2. How does the mechanical technical highschool graduate apply with industrial field? The result of study is as follows: 1. In case of employment's information and the industrial educationed cooperation, the workers who has the working history in less than 5 years takes short to find the job. National high school graduates and those who get the job through the school and the teacher changed their job at short period compared to other. 2. There was no benefit about the same major's worker at industrial field. The workers admitted that there is the exemption fo military service and the certification's allowance, only for which is related to their job. The longer the workers stay their job, the more they had the chance to get the exemption of military service. National highschool were carried out the curriculum well as planed especially for their major subjects. Whereas, the public and private highschools weren't. The seniors of their job and the coworkers are very helpful for learning the actual knowledge. The workers said that the school's curriculum and club activity weren't effective applying with their working field. 3. The study says that the important things of their job is the knowledge of their major. Those who 80% answered that the worker must improve the knowledge of their major to be a good engineer. Learning from their senior in working field was very helpful. The question above was ranked as the first. 4. The answer says that the new changed job's pay is more than the previous job. That is, the reason of leaving the job is the pay gap. The most dissatisfaction and problems in present job was the environment of working and the working condition. 5. Regarding to asking next year's plan, the answer says that keeping the job was ranked as the first. That answer means that they conservative.

• Korean Journal of Materials Research
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• v.1 no.3
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• pp.156-167
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• 1991

The purpose of this study is to develop a data base for material selection of turbofan engines, which is preferred in these days on many application due to their high performance with economical operation. Hundreds of Super Alloys have been developed by this time, each having special properties. Since it is very difficult task for a design engineer to select materials of adequate Properties for specific engine components, a good data bate is strongly desired to manage informations on various kinds of materials. However, no basic research is reported in this area so far in our country. The operating conditions such as temperature, pressure, rpm of spools are assumed to be provided by other mechanical studies. Creep rupture strength, corrosion resistance, yield strength, thermal expansion, melting point, etc., are considered as typical properties in this study to search a group of candidate materials. Formability, manufacturing or purchase cost can also be important variables to be considered. As a result of this study, a user-friendly computer program has been developed for input of new material information, interactive material selection, and output of selection results. Finally, discussion is presented from. the viewpoint of materials engineering. A method to evaluate the performance of the selected materials is also suggested.

• Journal of Biosystems Engineering
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• v.30 no.1 s.108
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• pp.45-55
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• 2005

Knowledge of the relationship between crop yield and yield-limiting factors is essential for precision farming. However, developing this knowledge is not easy because these yield-limiting factors are interrelated and affect crop yield in different ways. In this study, data for grain yield and yield-limiting factors, including crop chlorophyll content, soil chemical properties, and topography were collected for a small (0.3 ha) rice paddy field in Korea and a large (36 ha) upland corn field in the USA, and relationships were investigated with path analysis. Using this approach, the effects of limiting factors on crop yield could be separated into direct effects and indirect effects acting through other factors. Path analysis provided more insight into these complex relationships than did simple correlation or multiple linear regression analysis. Results of correlation analysis for the rice paddy field showed that EC, Ca, and $SiO_2$ had significant (P<0.1) correlations with rice yield, while pH, Ca, Mg, Na, $SiO_2,\;and\;P_2O_5$ had significant correlations with the SPAD chlorophyll reading. Path analysis provided additional information about the importance and contribution paths of soil variables to rice yield and growth. Ca had the highest direct effect (0.52) and indirect effect via Mg (-0.37) on rice yield. The indirect effect of Mg through Ca (0.51) was higher than the direct effect (-0.38). Path analysis also enabled more appropriate selection of important factors limiting crop yield by considering cause-and-effect relationships among predictor and response variables. For example, although pH showed a positive correlation (r=0.35) with SPAD readings, the correlation was mainly due to the indirect positive effects acting through Mg and $SiO_2$, while pH not only showed negative direct effects, but also negatively impacted indirect effects of other variables on SPAD readings. For the large upland Missouri corn field, two topographic factors, elevation and slope, had significant (P<0.1) direct effects on yield and highly significant (P<0.01) correlations with other limiting factors. Based on the correlation analysis alone, P and K were determined to be nutrients that would increase corn yield for this field. With the help of path analysis, however, increases in Mg could also be expected to increase corn yield in this case. In general, path analysis results were consistent with published optimum ranges of nutrients for rice and com production. We conclude that path analysis can be a useful tool to investigate interrelationships between crop yield and yield limiting factors on a site-specific basis.

• Journal of Fisheries and Marine Sciences Education
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• v.4 no.2
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• pp.109-120
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• 1992

The auther reported the distribution of fisheries high schools and arrangement of curriculum in Japan in the forward report, and describes on the outer apparance and substantiality of education of fisheries high schools in Japan in the present report. 1. The rate of population to the number of fisheries high school shows 2,350 thousands in Japan, compared with 3,250 thousands in Korea. Then the rate in Korea is 1.4 times as high as that in Japan. 2. The rate of pupil to the whole regular instructors for fundamental subjects and for vocational subjects in the fisheries high schools, and also the rate to the instructors for vocational subjects show 10.4 and 16.3 in Japan, compared with 18.2 and 30.2 in Korea. Then the rate in Korea is 1.8 times as high as that in Japan. In addition to the instructors for vocational subjects. trainer and assistants for technical training-are employed in Japan compared with no such instructors or assistants in Korea. Then the rate of pupil to the whole instructing staffs in Korea is 2.4 times as high as that in Japan. 3. 81 percents of training ships in Japan are larger than 400 gross tons, which is extremely higher to that in Korea. The rate of gross tonnage of the ships to the number of trainees shows 6.2 tons in Japan compared with 1.1 tons in Korea. Also such large dimensioned training ships are newly built every other 12 years. the construction cost per 1 gross ton of such ships are said as 2.5 to 3 million yen, which corresponds to 15 to 18 million wons, and is over 3 times as much as that in Korea. 4. The basic education on the marine field is widely diffused in Japan. For an example, swimming pools are prepared not only in fisheries high schools but also in primary schools although it is rate even in fisheries high schools or colleges in Korea. 5. Almost all provinces which locate on the seashore have at least one fisheries high school and the curriculum is arranged to match the needs of local districts, then the management of school is tightly linked to the local government. 6. Entrance system is also flexible and recommended entrance system for successors of fishermen is settled. 7. Re-education of instructors for the new subjects which should be prepared to match the demands of ages are supported by local government in the aspect of time and budget. 8. The special two-year course for advanced seamen' s education is attached to some fisheries high schools and the graduates are qualified to get the third grade marine officer's or engineer's liscence.

• Fire Science and Engineering
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• v.33 no.6
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• pp.87-94
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• 2019

Through a press release dated July 17, 2018, the Anti-Corruption and Civil Rights Commission recommended that the National Fire Agency develop preventive measures against fire in the "Indoor Archery Ground" and "Room Escape Café" etc., which were originally excluded from the category of "Publicly Used Establishments." This study developed the hierarchy of domains and indicators of measurement for fire risk assessment of the new business of publicly used establishments through the Delphi Method. It analyzed the goodness of fit scores (over 3.00) and secured an average score of 4.25. Using AHP analysis, the ratio of consistency for the domains of measurement of fire risk assessment was found to be 4.0%, which was lower than CR ≤ 0.1 (10%). The consistency of subsequent measurement indicators were distributed in the range of 0.1%~3.6%, and they were identified as being commonly consistent. The indicators of measurement appeared as follows in order of importance and priority: Type of Internal Passage of Establishment and Evacuation Capacity of Exit (0.316), Control of Ignition Source (0.141), Inherent Risk (0.106), Appropriateness and Adaptiveness of Fire Detection System (0.097), Control of Inflammables/Combustibles (0.084), Guides and Facilities helping Evacuation (0.075), Fire Resistant Structure and Finishing Materials (0.060), Compartmentalization and Emergency Exit (0.049), Risk of Fire Expansion (0.046), and Appropriateness and Adaptiveness of Fire Extinguishing Facilities (0.026). The findings of this study are expected to be expansively used as data for future research on the development of fire risk assessment indicators.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1357-1366
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• 2015

This study (II) aims to draw up the future-oriented construction policy recommendations based on the outcomes as a result of a broad research and conducting questionnaire surveys on the arguable issues raised by construction engineers for roads and bridges in the course of previous study (I) implementation. As for the question of "The term 'Construction Management (CM)' which currently is defined in two (2) ways", 45% of respondents have answered that two (2) different types of CM should be unified into one (1) CM type as is the case in most advanced countries. About the question of "The ways to educate the CM professionals", many respondents have preferred to acquire CM professional certificate after receiving education for a certain period of time from private CM training institutions. As for the question of The revised draft that the ICEC grade of special engineers for design, construction and quality control areas shall be "more than 78 points from a more than 75 points by the original draft." 52% of respondents preferred to maintain the original draft. About the question of "The reason why the CM system has not been working well yet." 62% of respondents have answered that the staff members who are in charge of handling public project procurements are concerned about the fact that their roles (or activities) might be deprived as a result of CM adoption. In order for the CM system to be activated, based on the notion that the construction projects must be out soured, the reshuffle of the headquarter organization of Ministry of Land, Infrastructure and Transportation (MLIT) should be preceded.