• Journal of the Korean Professional Engineers Association
• /
• v.12 no.1
• /
• pp.12-20
• /
• 1979

The early history of gun powder (black powder) and explosives was closely connected with the discovery of methods of preparing and purifing salpetre (potassium nitrate KNO$_3$). The Chineses apparently became acquainted with salpetre firstly on about 11th century, and they were possibly the original discoverers of salpetre for raw material of gun powder. The Egyptians called it “Chinese snow”, and it is significant that Chingis-Khan, the Mongol conqueror, took the Chinese eenginees with him in 1218 to use it for attacking the fortifications of the Persian cities. The black powder was invented by chance by Chinese alchemists during the Song dynasty (11th century) in the process of manufacturing medicine, and the powder was introduced to Europe by Mongol army. The manufacturing method of salpetre and gun powder was introduced to Korea from China in 1374, and the powder alld gunnery manufacturing project was developed by Mu Sun Choe(崔茂宣), the first Korean engineer late in Koryo dynasty. Coming in to Yi dynasty the explosive technic, extractive method of salpetre, and gunnery manufacturing process were developed greatly by Mu Sun Choe and Hai Sin Choe (崔海臣). However, confronting with the Japanes invasion at Imjin War (1597) with more powerful western style rifles which had been introduced from the Portuguese, on the contrary Korean army with the traditional guns couldn't compete with them. The Chochong(烏銃, the western rifle introduced in Japane) were much superior to the Chinese style traditional guns in the shooting power and striking efficiency. On the other hand, the Japanese battle ships armed only with the Chochong, when confronted with the Korean turtle shaped ships under the commanding of Admiral Yi Sun-Sin(李舞臣), were defeated by the Korean canons on the ships. The technical development of the modern powder industry in Korea. with the construction of four big explosive plants from 1930 to 1945, has resulted the mass-production of explosives. This study was purposed to investigate to the process with regard to the details of introduction to the explosive technology in Korea, and intended to give a help to the engineers who are engaged in study of the explosive technics by means of giving a spot light data on the early process of the designs, and making suggestion to the researchers for further study and invent a new and modern explosive.

• Journal of agricultural medicine and community health
• /
• v.34 no.1
• /
• pp.135-142
• /
• 2009

Objectives: This study was performed to investigate the changes in the prevalence and its related factors of the Clonorchis sinensis(C.S.) in the inhabitants at Goksung-Gun along Sum-Jin river after C.S. control intervention. Methods: The subjects were 416 among 699 in the 8 same villages selected by stratified cluster sampling in 1999. The formalin-esther sedimentaion technic was used for the C.S. egg detection and the questionnare for the related factors. The study was carried on from February, 2005 to March, 2005. Results: The prevalence of C.S. decreased significantly from 19.0% in 1999 to 11.3% in 2005. The signicicant factors in 1999 such as sex, age, area, raw fish eating habit and drink habit were not significant statistically. On the other hand factors such as the awareness of C.S. and the health behavior were changed significantly(p=0.034, p=0.021). Conclusions: These results suggest that C.S. prevalence became lower than previous study five years ago. But its control intervention should be extened to the general population regardless of sex, age, area, raw fish eating habits, drink habit and we need to make an effort to improve the awareness and the health behavior of C.S..

• Imaging Science in Dentistry
• /
• v.30 no.3
• /
• pp.155-158
• /
• 2000

The purpose of this paper is to explain the making procedure and the usage of receiver operating characteristic (ROC) curve for interpretation of radiographic images. The conventional radiograms obtained after the creation of the lesions in the acrylic plates and were enhanced in color. The observer were informed of which tooth to examine, the 'a priori' probability of a lesion present and the approximate diameter of the lesions. The two groups of films were interpreted separately by the same observer using the same rating scale. The following rating scale was used: A; definitely no lesion, B; probably no lesion, C; not sure, D; probably a lesion, and E; definitely a lesion. In analysis, for each observer the diagnostic results in terms of true positive (TP) and false positive (FP) decisions were plotted on a graph. The lowest point on the graph represents the TP and FP when only decisions designated as E according to the rating scale are included. The next point shows the TP and FP values when diagnoses designated as D are added and so forth. By connecting such plot points, a receiver operating characteristic (ROC) curves is obtained. The area under the curve represents the diagnostic accuracy resulting from a diagnostic performance at pure chance level and a value of 1.0 at perfect performance. This method has been known as an useful method to detect the minute difference for each radiographic technic, each observer and for the different lesion depths.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.6
• /
• pp.235-245
• /
• 2011

EBooks refer to electronic versions of books which are accessible via internet with forms of digital texts. In recent years, Amazon's Kindle digital eBooks has revealed the possibilities of success of the e-book market, which leads other companies to launch eBook service such as Google's eBook stores and Apple's iPad and eBook service. These reveal that the eBook market is finally showing a substantial amount of growth. Although the issue of technical support of eBook copyright protection emerges from the fast growing eBook marketplace, current technic of commercial DRM for protecting eBook copyright protection still has problems of non-comparability. Therefore, with the current technical status, DRM comparability problems, which have already occurred in music DRM environment, would also happen in eBook environment. This study suggests a standard framework to support eBook DRM comparability. When development of the standard reference software for eBook DRM comparability is completed, the sources will be registered as shareware to be open to public.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.72-79
• /
• 2010

The significant of continuous welded rail (CWR) management is growing because KORAIL has the plan to convert the whole of conventional railway lines into CWRs through continuous activities since constructed the CWR track with 1.8km in Gyeongbu line in 1966. The CWR recently is needed a efficient management method because it is difficult to manage the CWR by the poor of technic and equipment, limited maintain labor force and shorted the maintain work time of CWR caused by industrialization, greenhouse effect and global warming In this point, The 70ton Tenser's which is using in the rail site has been analysised with no extra tenser's capacity in case of the under low temperature and exceed the length of 1km as a result of reviewing the CWR-related rules and standards, a series of records of safety accidents, operation obstacles, and the situation of broken rails published by KORAIL, existing rail temperature measurements, and CWR researches. Therefore avoid the excessive plan of the first set-up section, choice the proper time in the normal temperature that is possible to weld the rail, turning the difference of rail temperature and Installation temperature down is desirable.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
• /
• v.27 no.2
• /
• pp.114-121
• /
• 2016

Background and Objectives : Many students major in applied music singing have various difficulties in phonation when they sing or perform. But the studies about this cause are lack. The purpose of this study is whether singing voice therapy based on vocal music is effective or not to applied music singing students that have difficulties in phonation. Materials and Methods : Singing voice therapy program had been done to 8 students major in applied music singing during 7 weeks. We did laryngeal stroboscope, perceptual, acoustic and aerodynamic examination before and after singing voice therapy to this students. And we studied post examination results have differences or improvements compared to pre examination results. Results : Four male students don't have effective improvement after singing voice therapy but they shows slight improvement in aerodynamic examination values compared to pre examination values. Four female students shows improvement in aerodynamic examination values and pitch range increasing. Above all, one student's vocal nodules disappeared after singing voice therapy. Conclusion : Singing voice therapy based on music singing is very effective to the students major in applied music singing. Above all, their curriculum in applied music singing should include phonation training based on music singing before training perform and technic practices.

• Journal of Fashion Business
• /
• v.10 no.4
• /
• pp.1-15
• /
• 2006

The purpose of this study was to analyze the image perception of dress shirts according to perceiver's residency and shirts style, and to investigate the shirts preference according to style of dress shirts, and to find out the men's aesthetics consciousness for shirts, and to analyze between the image perception and the usage of mass-media, for developing the possibility & strategy of the dress shirts market in men's wear market for the apparel marketers and manufactures. For this study, the data obtained from 321 respondents were analyzed by descriptive statistics, Pearson's simple correlation, ANOVA. The results from the study were as follow ; The 6 stimuli for image perception rated on 5 point Likert-type scales in the 12 features were evaluated by perceivers. By the best 3 features abstracted, shirts style concepts were decided such as, Basic style by the best 3 features of the first stimulus, and Soft style by the best 3 features of the second stimulus, and Sophisticate style by the best 3 features of the third stimulus, and Modern casual style by the best 3 features of the fourth stimulus, and Modern mannish style by the best 3 features of the fifth stimulus, and Trendy style by the best 3 features of the sixth stimulus. The modern casual style was estimated highly by respondents in Daejon. The respondents in Seoul prfered the basic style to other style. There were significant differences in evaluating between preferences of shirts style and pattern. Of the 82 respondents(26.8%) with the preference of bold london stripe, the 52 respondents estimated Modern casual style in bold london stripe. The fashion consciousness of the respondents in Seoul was estimated higher than in Daejon. But, the respondents in Daejon in the consciousness for the coordination knit cardigan and V zone was estimated higher than in Seoul. Also, the 31 respondents with the preference of Sophisticate style were the highest in fashion consciousness. The respondents estimated that the first important thing in buying dress shirts is 'Design(41.4%). and next is quality(17.8%). Results revealed that Daks ranked best brand (13.7%), and Renoma ranked best two brand (6,5%). And, the 35.5% respondents estimated that the first important information which influenced on buying dress shirts was the store display, next was internet(15.9%). Finally, I propose that the best strategy for men with low fashion consciousness is to upgrade salesmen' coordination technic and fabric knowledge, and store management with story attracting customers.

• Korean Journal of Soil Science and Fertilizer
• /
• v.16 no.4
• /
• pp.353-357
• /
• 1983

A field study was conducted for 20 soil columns to investigate the denitrification in the grassland with a method introducing $C_2H_2$ in the denitrifying system. Since acetylene blocked the pathway from $N_2O$ to $N_2$, all the free products of denitrification consisted of nitrous oxide. In this study, denitrification was measured as $N_2O$. Results are as follows. 1. In most of boils examined, denitrification was observed as $N_2O$ when acetylene was introduced into the denitrification system while $N_2O$ was scarcely evolved without acetylene in the system. 2. Denitrification occurred even in the grassland soils when they were saturated with water. Denitrification was nil or negligible without water saturation. 3. Denitrification loss far 3 days incubation(from 13th to 16th day after urea application) was 4.2% in average and 14.2% in maximum. 4. Soil chemical properties such as nitrate nitrogen, nitrite nitrogen, total nitrogen, total carbon and mineralizable carbon did not show clear relationships with denitrificatien, probably since soil chemical properties were analysed for the soils after incubation.

• Journal of the Korean Applied Science and Technology
• /
• v.30 no.2
• /
• pp.305-311
• /
• 2013

PLA(polylactic acid), one of biodegradable polymers was blended with various amounts of wood pulp powder through solution blending technic to verify the effect of reinforcing pulp amount on the mechanical properties of blend films. Also these blend films were further modified with TDI(toluene diisocyanate) as crosslinking agent to introduce urethane functions by reaction of pulp hydroxyl groups and isocyanate. As a result, the tensile strength of blend film with 0.25 wt% pulp was increased from $565.25kg_f/cm^2$ for PLA film itself to $624.20kg_f/cm^2$. However, elongation of this film was decreased by 50% of that of PLA film itself. Only PLA/pulp blend film further modified with 500% of TDI/0.25 wt% pulp showed the slightly increased tensile strength but decreased elongation. Melting point and glass transition temperature of PLA/pulp blend films were confirmed by using Differential Scanning Calorimeter(DSC). Thermal stability of these blend films measured by TGA showed only a slight increase at temperature lower than $300^{\circ}C$.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.8 no.4
• /
• pp.67-77
• /
• 2000

For successful privatization of environmental facility, a sound environmental policy is required to satisfy social motivation and economic. The primary purpose of environmental facility is not profit, but to supply a good quality service, an efficient management tool is needed to run the facility. In foreign countries, the privatization policy was originally based on the principle of complete competition achieving economic effiency. There were efficient cooperation and division of labor between civillian and public sector. First of all, the local government had independant budget. But, we found that the environmental facility have two important problems, the first is low effiency of operation and the second is comsumed to government finances as a homemade rate 50% in the technic application For a successful privatization of the environmental facility, The law of private capital introduction should be amended to promote fund raising. There are some other strategies ; overcoming of Nimbyism, research development of the privatization, field trip to the successful foreign environmental facilities. To support an efficient privatization policy, the environmental budget should be managed by cost-benefit analysis.