Seo, Junhyuk;Kwon, Kilsung;Choi, Ju Chan;Baek, Jehyun
Transactions of the Korean Society of Mechanical Engineers B
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v.39
no.2
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pp.153-159
/
2015
In this study, a 2-W micro-gas turbine engine was designed using micro-electro-mechanical systems (MEMS) technology, and analytical and experimental investigations of its potential under actual combustion conditions were performed. An ultra-micro-gas turbine contains a turbo-charger, combustor, and generator. A compressor, turbine blade, and generator coil were manufactured using MEMS technology. The shaft was supported by a precision computer numerical control machined air bearing, and a permanent magnet was attached to the end of the shaft for generation. An analysis found that the cooling effect of the air bearing and compressor was sufficient to cover the combustor heat, which was verified in an actual experiment.
In the 7th century, Prince Shoudoku built the Horyu temple at Nara, when Buddhist culture in Japan had highly prospered after Buddhism were transmitted to Japan from Korea. At the same time, the three ancient country of Silla, Koguryo, and Baekjae had generally effected on Japanese culture and life as well as Buddhist events, religious services and sacrificial offerings in form. And even now there are kept above one thousand of tablewares which was used at the age and was made of wood and alloy manufactures from Han peninsular in Seisoin at Nara. Through these historical backgrounds, it could be presumed that the religious services and the sacrificial offerings for Prince Shodoku for above 1300 years help us to study and estimate the ancient dietary culture of Korean and Japanese. There are several points of similarities which are remained and maintained in Han Peninsular. 1. They used high filling method of the secrificial offerings and high receptacles in the religious service. 2. The cakes were mainly made of nonglutinous rice tharr glutinous rice 3. They decorated the pheonix instead of flowers and the other kinds of birds in Korea. 4. Kakiage of fried confectionary was founded in many kinds of them at present.
One of the assimilation policies of Japanese imperialism for the permanent domination in the colonial Joseon is the theory of integration of Japan and Joseon. The theory of integration of Japan and Joseon is a logic that Joseon (Korea) and Japan (Wae) were connected to the same ancestor on the basis of ancient myths. Also it is the assimilation ideology to justify the Colonial rule of those days through the objectification of historical identity or affinity of political and cultural relations of ancient Korean peninsula and Japan (Wae). Japan reorganized our history to meet the colonial point of view, as part of the assimilation policies based on the theory of integration of Japan and Joseon. On the other hand Japan attempted to objectify them through archaeological research and the reinterpretation of the historical remains. The survey, reinterpretation and tourist of the historic sites in historic cities such as Gyeongju and Buyeo were promoted in this context. In particular, the Buyeo, a capital of Baekje, was emphasized upon the close relevance and affinity between Sabi, Baekje and ancient Asuka (飛鳥) in Japan through research and reinterpretation on the Historic Sites. Based on them, Historic Sites Tourism was conducted by reconstructed historic sites toward the colonial Korean. In addition, after the Sino-Japanese war in 1937, Japan tried to realize the politics of space by upgrading and idealizing Buyeo as homeland or Shinto (神都) related to Japanese ancient mythology of the Asuka culture. This paper investigated in what context research, reinterpret and tourist of the historic sites progressed on Buyeo area and how it had soaked through the general public in the Japanese colonial era. First, it is on historic sites. Historic sites research on Buyeo area made an attempt by Sekino Tadashi in 1909 for the first time and the re-excavation of the old burial mounds and temple sites during the Japanese colonial period. Sekino set up a cultural relationship and influences between the ancient China (梁), Korea (百濟) and Japan (倭). Also, he emphasized that Sabi, Baekje largely received influence of Chinese culture and Baekje and Japan Asuka culture had closely relations and affinity. These views had been consistent during the Japanese colonial period. Second, it is the reinterpretation on Historic sites. Buyeo Historic Sites Preservation Society (Buyeo Gojeok Bojonhoe) was established in 1915 and Osaka Kintaro, curator of Baekje exhibition hall redefined the relationship between ancient Japan and Baekje as perspective of the assimilation ideology through the post contextual interpretation. In particular, they emphasized on the close relevance between Baekje's Historic sites and Japan, through the reinterpretation of Nakhwaam, Goransa and Cheongmasanseong. Third, it is the tourist on Historic sites. Buyeo Historic Sites Preservation Society played a leading role in Tourist on Historic sites at the Buyeo region. The main tourist destinations and course were restructured through a reinterpretation on the historic sites. Japan would like to show Buyeo as ideology area, homeland of ancient Japanese culture, toward the Koreans under Japanese colonial era. Thus, research, reinterpretation, and tourism on Historic sites were promoted while they were closely related to each other. The promoting body was Joseon Chongdokbu and pro-Japanese interest group. It's point was 'made' and 'shown' by the eyes of others and a rediscovery of Buyeo as representational space of colony.
At the Bujang-ri Site, Seosan, South Chungcheong Province, around 220 archaeological features, including semi-subterranean houses and pits of Bronze Age and semi-subterranean houses, pits, and burials of Baekje period had been identified and investigated. In Particular, mound burials No. 5 of 13 of Baekje mound burials yielding a gilt-bronze cap along with other valuable artifacts drew international scholarly attention. The gilt-bronze cap from the mound burial No. 5 is a significant archaeological data not only in the study of Baekje archaeology but also in the study of international affairs and exchange at that time. At the time of exposure, the gilt-bronze cap was already broken into a number of pieces and seriously damaged by corrosion, and hardening and urethane foam were necessary in the process of collecting its pieces. Ahead of main conservational treatments on cap, X-ray photograph and CT(computerizes tomography) were taken in order to examine interior structure of the cap and to decide appropriate treatments. In the five layers identified in the profile of cap, a textile layer was set between a metal and a layerof bark of paper birch for avoiding direct contact of the metal and the bark of paper birch. Analyses were executed for examining textile layer and a layer of fibroid material. According to microscopic analysis, while the textile layer consisted of the simplest plain fabric with one fold among three kinds of textile structures, the layer of fibroid material was mixed with two or three kinds of fibers. A comparative analysis with standard sample using FT-IR (Fourier Transform Infrared Spectroscopy) announced that both textiles and fabrics were hemp. Analysis of kind of the paper birch resulted in barks of paper birch with 15 fold. A metallographic microscope, SEM, and WDS were used for the analysis of microscopic structures of plated metal pieces. While amalgam plating was treated as a plating method, the thickness of the plated layer, a barometer of plating technique, was ranged from $1.72{\mu}m$ to $8.67{\mu}m$. The degree of purity of gold (Au) used in plating was 98% in average, and less than 1% of silver (Ag) was included.
Park, Jae Hyeon;Sohn, Dong Kyung;Kim, Chang Hyun;Baek, Je Hyun
Transactions of the Korean Society of Mechanical Engineers B
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v.40
no.2
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pp.75-83
/
2016
Since a turbomachine has complex flow characteristics, which are caused by adverse pressure gradient and high speed motion, an elaborate turbulence model is needed to accurately predict the flow. Some turbulence models such as an algebraic or a two-equation eddy viscosity model have been used for in-house RANS-code, but it is difficult to obtain good result for several complex flows. In this study, Durbin's V2-F turbulence model, which has been known for better prediction for severe flow separation, is applied to T-Flow. It was validated for simple cases such as channel and compressor cascade, and its applicability to turbomachinery was shown by analyzing internal flow of a single rotor. As a result, the V2-F turbulence model shows better blade surface pressure distribution than the one-and-two equation turbulence model.
The eddy viscosity turbulence models were applied to predict the flows through a cascade, and the prediction performances of turbulence models were assessed by comparing with the experimental results for a controlled diffusion(CD) compressor blade. The original $\kappa-\omega$ turbulence model and $\kappa-\omega$ shear stress transport(SST) turbulence model were used as two-equation turbulence model which were enhanced for a low Reynolds number flow and the Baldwin-Lomax turbulence model was used as algebraic turbulence model. Farve averaged Wavier-Stokes equations in a two-dimensional, curvilinear coordinate system were solved by an implicit, cell-centered finite-volume computer code. The turbulence quantities are obtained by lagging when the men flow equations have been updated. The numerical analysis was made to the flows of CD compressor blade in a cascade at three different incidence angles (40. 43.4. 46 degrees). We found the reversion in the prediction performance of original $\kappa-\omega$ turbulence model and $\kappa-\omega$ SST turbulence model when the incidence angie increased. And the algebraic Baldwin-Lomax turbulence model showed inferiority to two-equation turbulence models.
It has been indicated that the rotor/stator interaction has distinct causes of unsteadiness, such as the viscous vortex shedding, wake/stator interaction and potential rotor/stator interaction. In this paper, the mechanism of unsteady potential interaction in one stage axial compressor is numerically investigated for blade row ratio 1:1 and 2:3 at design point and for blade row ratio 2:3 at off-design point in two-dimensional view point. The numerical technique used is the upwind scheme of Van-Leer's Flux Vector Splitting(FVS) and Cubic spline interpolation is applied on zonal interface. In this study the flow unsteadiness due to potential interaction are found to be larger in blade row ratio 2:3 than in 1:1. The total pressure rise in blade row ratio 2:3 is closer to the real value in design point than that in 1:1. The change of unsteady pressure amplitude according to the variation of stator exit pressure is very small.
This study has to do with the architectural exchanges between the ancient Korea and China. There are two parts in this paper. The first part is concerned with bibliographical and archeological studies between two regions. The latter part is to compare and syudy the architectural style of china with the architectural style of BAEGJE in those days. At any rate, this paper is related to the first part of them. The most important purpose of this paper is more clearly to inquiry the BAEGJE Architecture. BAEGJE Architecture is the most insufficient in researches of the era of Three Kingdoms' architecture of Korea until now. Because the architectural Matrrials is also the most insufficient condition in Three Kindoms, in order to inquiry the architectural style of BAEGJE clearly, we will be able to get the clue as inquring the relations of the chinese which they exchanged most frequently. The first part of this paper is $appraoc{\sim}ed$ in two methods of the study. One is the biblilographical research and the other is the archeological research. The writer could find that there were many exchage relations in the bibliographocal and archeological fieds, as a result of this study. The writer could confirm that there were nearly coexisting similiar styles of the Architecture.
In this study, it has compared and investigated the architecture of Six-Dynasty in China which was the same period of Baegje. There are no buildings to remain as a Baegje's architecture, but the architectural traces are remained. Especially, the architectural traces in Six-Dynasty are much left in cave temples. The reason to compare the architecture between China and Baegje intends to restore the Baegje's architectural style ultimately. The two countries, China and Baegje, were very close and they traded each other at that time. In the method of comparison, it has been investigated the form, the style and characteristics in each parts such as podium, column base, column, doors and windoors, brackets and roofs. As a result of the study, it has shown that the Baegje's architecture was not splendid compared to the architecture of Six-Dynasty. Baegje developed it's own architectural technique and used it only to the Baegje architecture. Since there was historical records that Baegje sent it's own architectural engineers to surrounding countries, Silla and Japan, it confirms that Baegje's architectural techniques were excellent. We need more time and constant research to restore the Baegje's architectural style ahead of time.
It is increasing to make an efforts on preventing natural river environment and preserving natural river ecosystem as development is unavoidable. In the case of inconsistent river flow caused by reservoir development, fishway is an alternative to secure fish diversity and preserve existing river ecosystem but existing fishway was established without full study for their functions. In this study, hydraulic characteristics of natural fishway established on Beakje weir's right side were analyzed. The results show that the fishway has reasonable depth and velocity condition which inhabit condition is enough for a dominant species. For assessing the optimal design of fishway, the Weighted Usable Area (WUA) was calculated by using two dimensional numerical model under the ordinary flow condition. The comparison results for various pool widths in the fishway show that the designed width has maximum WUA for adult Zacco platypus but WUA is maximized with 1m wider pool width than designed width for spawning.
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