• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.49-59
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• 1984

Optimizing investigation of characteristics of underwater welding by a gravity type arc welding process was experimentally carried out by using six types of domestic coated welding electrodes for welding of domestic marine structural steel plates (KR Grade A-1, SWS41A, SWS41B,) in order to develop the underwater welding techniques in practical use. Main results obtained are summarized as follows: 1. The absorption speed of the coating of domestic coated lime titania type welding-electrode became constant at about 60 minutes in water and it was about 0.18%/min during initial 8 minutes of absorption time. 2. Thus, the immediate welding electrode could be used in underwater welding for such a short time in comparison with the joint strength of in-atmosphere-and on-water-welding by dry-, wet-or immediate-welding-electrode. 3. By bead appearance and X-ray inspection, ilmenite, limetitania and high titanium oxide types of electrodes were found better for underwater-welding of 10 mm KR Grade A-1 steel plates, while proper welding angle, current and electrode diameter were 6$0^{\circ}C$, above 160A and 4mm respectively under 28cm/min of welding speed. 4. The weld metal tensile strength or proof stress of underwater-welded-joints has a quadratic relationship with the heat input, and the optimal heat input zone is about 13 to 15KJ/cm for 10mm SWS41A steel plates, resulting from consideration upon both joint efficiency of above-100% and recovery of impact strength and strain. Meanwhile, the optimal heat input zone resulting from tension-tension fatigue limit above the base metal's of SWS41A plates is 16 to 19KJ/cm. Reliability of all the empirical equations reveals 95% confidence level. 6. The microstructure of the underwater welds of SES41A welded in such a zone has no weld defects such as hydrogen brittleness with supreme high hardness, since the HAZ-bond boundary area adjacent to both surface and base metal has only Hv400 max with the microstructure of fine martensite, bainite, pearlite and small amount of ferrite.

• Korean journal of applied entomology
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• v.49 no.4
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• pp.375-384
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• 2010

We tried to establish the history of outbreaks and control methods of 'hwangchung' in Joseon Dynasty, uncovering the biological reality of the 'hwangchung' (called hwang or bihwang) analyzed through the Database program on 'the Annals of the Joseon Dynasty' and 'the Emollment of Haegoeje', two of the finest examples of classical historical records. The total number of articles on the outbreak of the hwangchung is 261 in the Annals of the Joseon Dynasty and 65 in the Emollment of Haegoeje. There were four peaks by hwangchung throughout the Joseon Era. Among them, the periods of King Taejo to King Sejong had the highest incidence. By comparing the number of records of the hwangchung from the Annals of the Joseon Dynasty with that in the Emollment of Haegoeje during the same period, results show the former was less than the latter, 35 vs 65. However, both records were relatively inconsistent with each other. Insect pests in forests as well as in agriculture were included in the biological identities of the hwangchung in the Joseon Dynasty periods, which is in accordance with those of Saigo's. The taxonomic identity could be confirmed in only 25 cases (9.5%) among the articles on hwangchung. It largely coincided with Paik's opinion: II in armyworm, nine in moth larva, one in rice stem borer, two in migratory locust, one in planthopper and one in rice-plant weevil. Therefore, it is not reasonable to regard hwangchung as a migratory locust or grasshopper only. The number of reports on the occurrence of hwangchung in the Annals of the Joseon Dynasty was 173 (66% of the total) and 47% of them were just simple reports, which means the report itself on the appearance of hwangchung was very significant. The reports on controlling insect pests were of low frequency, in 20% (34 cases) of the total reports, capturing insect pests or holding traditional ceremony called 'Poje'. Among them, only one case related to the treatment of seeds to prevent the damage by hwangchung was published in the King Sejong period. There were 37 discussions about changes and management of government policies due to disasters by hwangchung. They were mostly about relief or tax cut to the people who suffered damage and about cancellation of recruiting people to military training, constructing castles, and so on. It seems that not only the people but also the king was influenced by the hwangchung. In the case of King Seongjong, he referred to the stress of the prevention measure of locusts in 10 articles. The damage also had an effect on abdication in the reign of King Jeongjong.

• The Korean Journal of Petroleum Geology
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• v.2 no.2 s.3
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• pp.43-50
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• 1994

The geologic structure of Gongju Basin, which is a Cretaceous sedimentary basin located on the boundary of Gyeonggi Massif and Ogcheon Belt, is modeled by using gravity data and interpreted in relation with basin forming tectonism. The electrical survey with dipole-dipole array was also conducted to uncover the development of fractures in the two fault zones which form the boundaries of the basin. In the process of gravity data reduction, the terrain correction was performed by using the conic prism model, which showed better results specially for topography having a steep slope. The gravity model of the geologic structure of Gongju basin is obtained by forward modeling based on the surface geology and density inversion. It reveals that the width of the basin at its central part is about $4{\cal}km$ and about $2.5{\cal}km$ at the southern part. The depth of crystalline basement beneath sedimentary rocks of the basin is about $700{\~}400{\cal}m$ below the sea level and it is thinner in the center than in margin. The fault of the southeastern boundary appears more clearly than that of the northwestern boundary, and its fracture zone may extended to the depth of more than $1{\cal}km$. Therefore, it is thought that the tectonic movement along the fault in the southeastern boundary was much stronger. These results coincide with the appearance of broad low resistivity anomaly at the southeastern boundary of the basin in the resistivity section. The fracture zones having low density are also recognized inside the basin from the gravity model. The swelling feature of basement and the fractures in sedimentary rocks of the basin suggest that the compressional tectonic stress had also involved after the deposition of the Cretaceous sediments.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.331-338
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• 2018

The purpose of this study was to determine the optimum sterilization conditions for the production of retorted steamed egg using response surface methodology. Sterilization processes for eighteen conditions using varying sterilization temperature ($X_1$), time ($X_2$), and method ($X_3$) as the independent variables were carried out through a $3^2{\times}2$ experimental factorial design. Quality evaluations after sterilization included measurements of $F_0$ value ($Y_1$), peak stress ($Y_2$), pH ($Y_3$), color value ($Y_{4-6}$), and organoleptic test [preference for appearance ($Y_7$), overall acceptability ($Y_8$), and preference for texture ($Y_9$) and egg taste ($Y_{10}$)]. Dependent variables ($Y_{1-10}$) of eighteen conditions were more affected by temperature and time than by the sterilization method. Eight factors were selected among the dependent variables as significant factors related to the quality of the steamed egg. Finally, by establishing an optimum range of each dependent variable and contour analysis, the optimum sterilization conditions for the production of steamed egg were determined to be $120^{\circ}C$ for 25 min using a 2-step sterilization process.

• Korean Journal of Heritage: History & Science
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• v.50 no.4
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• pp.148-165
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• 2017

Mural paintings drawn inside ancient tombs are very sensitive to changes in the environment such as temperature and humidity, especially the finish layer of the tomb murals differ in preservability depending on the material properties and humidity conditions. In this study, I examined the mural painting of Songsan-ri Tomb No.6, where the finish layer was made of earth, and identified the physical changes that can occur due to drying, depending on the material properties of the finish layer. I found out through particle size analysis that the finish layer of the mural painting in Songsan-ri Tomb No.6 is about 85.0wt% below silt, about 14.0wt% clay therein, mostly composed of silt and below clay. I also found out through physical property evaluation that surface change rate of samples showed the largest change at 15.5% in reproduced finish layer sample made up of bentonite, followed by 7.8% of reproduced finish layer sample made up of celadon soil, 6.3% of reproduced finish layer sample made up of loess, 6.2% of reproduced finish layer sample composed of white clay and the same order of change in appearance was confirmed in each sample consisted of soil. In addition, it showed the same trend of surface change rate, and the bentonite condition showed the largest change, in the measurement of shrinkage rate and expansion rate. The experiment shows that the finish layer composed of soil is affected by cohesion among particles according to the content of fine parts and the relationship between the agglomeration due to the content of the differentiated part and the stress due to the expansibility depending on the kind of the clay mineral etc. Therefore, it can be concluded that the physical damage occurred in the mural painting finish layer of the Songsan-ri Tomb No.6 is related to the factors such as the material characteristics of the soil and the highly humid environmental change inside the tomb.

• The Journal of Korean Philosophical History
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• no.32
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• pp.309-336
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• 2011

There were various linking points that connect Li xue(Neo-Confucianism) to aesthetics in Song Dynasty as following. 1. The traditional moral as "pursuing pleasure of Kong-zi and Yan Hui" 2. Esteem of "life and vitality". Scholars of Li xue in Song regarded the pleasure of acting up to "benevolence" as a beauty, and this benevolence originated in the "heaven and earth; the universe". "Benevolence", that is to say, is name of the nature that continuous reproduction breed in an endless succession by "Yin-Yang the universe", thus the natural "life and vitality" of the "heaven and earth" as the matter of course is the perfect beauty. 3. An idea of "serene contemplation". Originally the "serene contemplation" belongs to discipline of "Li xue", however simultaneously this conception was entirely applicable to aesthetic point of view. 4. Cosmological consciousness. In the same manner, the "pleasure" which is moralistic and moreover aesthetic is indivisible from cosmic contemplation itself. Because of this point, the art and aesthetics of Song Dynasty self-consciously had the cosmological consciousness in its fullness. 5. Respect of beauty of nature. Scholars of "Li xue" considered as : no matter what "Li" or "Qi" that producing all things is "coming of itself", that is by no means artificially operated or prearranged in advance. Such standpoint was applied to creative art and made art of Song Dynasty esteem beauty of nature (coming of itself) exceedingly. 6. Laying stress on "disposition". Scholars of "Li xue" ordinarily valued much of "disposition of a sage", consequently this tendency influenced on aesthetics. "disposition" indicates the whole impression that one who has appearance and the inside(personality, temper, thought, etc.) gives to others. By putting that impression into practice of art and literature, it is to materialize the works of art as a unity of form and subject, also as an expression of human existence that breathed into one's sensibility on the whole. 7. Principles of "completing inquiry", "study the laws of nature by close access" of "Li xue". These principles made art and literature of Song Dynasty take a serious view of "Li" of all over the universe, so made them close investigate things, and after all have achieved very remarkable characteristic in art and literature, especially in paintings of Song Dynasty. Theory of painting in Song Dynasty had occupied considerably high position in Chinese aesthetic history. It was positively superior to former generations no matter what in quantity or in theoretical minuteness and its systematic level. Undoubtedly the Chinese theory of painting had been achieving development time after time since Song Dynasty. However if we could make a comparison it with every single period (ex. Yuan, Ming, and Qing Dynasties), there is no prominent period than Song Dynasty in theory of paintings. Song period had number of essays of Landscape painting.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.201-209
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• 2010

Generally, PSC girder bridge uses total gross cross section to resist applied loads unlike reinforced concrete member. Also, it is used as short and middle span (less than 30 m) bridges due to advantages such as ease of design and construction, reduction of cost, and convenience of maintenance. But, due to recent increased public interests for environmental friendly and appearance appealing bridges all over the world, the demands for longer span bridges have been continuously increasing. This trend is shown not only in ordinary long span bridge types such as cable supported bridges but also in PSC girder bridges. In order to meet the increasing demands for new type of long span bridges, PSC hollow box girder with H-type steel as compression reinforcements is developed for bridge with a single span of more than 50 m. The developed PSC girder applies compressive prestressing at H-type compression reinforcements using unbonded PS tendon. The purpose of compressive prestressing is to recover plastic displacement of PSC girder after long term service by releasing the prestressing. The static test composed of 4 different stages in 3-point bending test is performed to verify safety of the bridge. First stage loading is applied until tensile cracks form. Then in second stage, the load is removed and the girder is unloaded. In third stage, after removal of loading, recovery of remaining plastic deformation is verified as the compressive prestressing is removed at H-type reinforcements. Then, in fourth stage, loading is continued until the girder fails. The experimental results showed that the first crack occurs at 1,615 kN with a corresponding displacement of 187.0 mm. The introduction of the additional compressive stress in the lower part of the girder from the removal of unbonded compressive prestressing of the H-type steel showed a capacity improvement of about 60% (7.7 mm) recovery of the residual deformation (18.7 mm) that occurred from load increase. By using prestressed H-type steel as compression reinforcements in the upper part of cross section, repair and rehabilitation of PSC girders are relatively easy, and the cost of maintenance is expected to decrease.