• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.67-79
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• 2010

Severe flexural vibration of the rotor shaft of a Francis turbine runner was experienced in the past. It was shown that the vibration was caused by the fluid forces and moments on the backshroud of the runner associated with the leakage flow through the back chamber. The aim of the present paper is to study the self-excited rotor vibration caused by the fluid force moments on the backshroud of a Francis turbine runner. The rotor vibration includes two fundamental motions, one is a whirling motion which only has a linear displacement and the other is a precession motion which only has an angular displacement. Accordingly, two types of fluid force moment are exerted on the rotor, the moment due to whirl and the moment due to precession. The main focus of the present paper is to clarify the contribution of each moment to the self-excited vibration of an overhung rotor. The runner was modeled by a disk and the whirl and the precession moments on the backshroud of the runner caused by the leakage flow were evaluated from the results of model tests conducted before. A lumped parameter model of a cantilevered rotor was used for the vibration analysis. By examining the frequency, the damping rate, the amplitude ratio of lateral and angular displacements for the cases with longer and shorter overhung rotor, it was found that the precession moment is more important for smaller overhung rotors and the whirl moment is more important for larger overhung rotors, although both types of moment due to the leakage flow can cause self-excited vibration of an overhung rotor.

• Economic and Environmental Geology
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• v.4 no.1
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• pp.11-18
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• 1971

The geotectonics and geomorphic structure of Korea resulted from the Song-rim Disturbance and the Daebo orogenic movements. Afterward this mountainous peninsula underwent several geological changes on a small scale, and it was also claimed that the steady rising of the elevated peneplain of the eastern coast and the submerging of the southwestern coastal area are largely due to the tilted block movement. These views have been generally accepted good in several ways, but they are limited in range or lacking in theoretical integration. The present writer investigated the geology of the Mt. Chi-ri-san and the Honam coal mining area for a geological map in 1965, respectively. The results of these studies convinced the present writer that the conventional views, which were based upon a theory of lateral pressure should be reconsidered in many respects, and more recent studies made it clear that the morphological development in the southwestern area can be better explained by the orogenic movement and rock control. The measurement of submerging speed of the western coastal area (Pak. Y. A., 1969) and a new account on the geology and tectonics of the Mid-central region of South Korea (Kim O.J., 1970) act as an encouragement to a new explanation. The present writer's researches on the extreme southwestern portion of the peninsula show that the steady submerging of this area cannot be attributed to a simple downthrown block phenomenon caused by block movement. It is no more than the result of the differential movement of uplifting in the eastern and western coastal areas and the rising of sea-level in the post-glacial period. This phenomenon could be easily explained by the comparison of the rate of rise in sea-level and amount of heat flow between Korea and other areas in the world. The existance of the erosional planes in the Sobaik-San ranges also provide an evidence of an upheaval in the western coast area. Though the Sobaik-San ranges largely follow the direction of the Sinian system. They consist of the numerous branches, whose trends run more or less differently from their main trend because of the disharmonic folding, are converged into Mt. Sobaik-San and Chupungryung. The undulation of the land is not wholely caused by orogenic movements, where as the present writer confirmed that the diversity of morphological development is the direct reflection of geological conditions such as rocks and processes which constitute the basic elements of geomorphic structure. An east-west directed mountain range which could be named as Hansan mountain range, was claimed to be oriented by the joint control. The geological conditions such as a special erosion and weathering of agglomerate and breccia tuff usually produce pot-hole like submarine features which cause the whirling phenomenon at the southwestern coast channel.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.78-85
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• 2004

As an ozone contactor, we newly adopted HJLR (High-performance Jet Loop Reactor) for the decolorization of Reactive black 5 and the mineralization of oxalic acid, which has been applied exclusively in biological wastewater treatments and well-known for high oxygen transfer characteristics. The ozonation efficiency for organic removals and ozone utilization depending on the mass transfer rate were compared to those of Stirred bubble column reactor, which was controlled by varing energy input in the HJLR and Stirred bubble column reactor. The results were as follows; first, the decolorization rate of Reactive black 5 in the HJLR reactor was nearly proportional to the increasing $k_La$. When the $k_La$ was increased by 25 % from $13.0hr^{-1}$ to $16.4hr^{-1}$, 30 % of the k' (apparent reaction rate constant) was increased from 0.1966 to $0.2665min^{-1}$ (Stirred bubble column; from 0.1790 to $0.2564min^{-1}$). Ozone transfer was found to be a rate-determining step in decolorizing Reactive black 5, which was supported by that no residual ozone was detected in all of the experiments. Second, the mineralization of oxalic acid was not always proportional to the increasing $k_La$ in the RJLR reactor. The rate-determining step for this reaction was OH(OH radical) production with ozone transfer, because residual ozone was always detected during the ozonation of oxalic acid in contrast with Reactive black 5. This result indicates that the increase of $k_La$ in the HJLR reactor is beneficial only when there are in ozone transfer limited regions. In addition, regardless of $k_La$, the mineralization of oxalic acid was nearly accomplished within 60 minutes. It was interpreted as that the longer staying of residual ozone by whirling liquid in the HJLR reactor contributed to an high ozone utilization(83-94%), producing more OR radicals.

• Applied Microscopy
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• v.35 no.4
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• pp.55-63
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• 2005

The characteristics of primary cultured rat brain microvessel endothelial cells (RBMECs) were studied using microscopy, immunohistochemistry and measuring of transendothelial electrical resistance (TER). The RBMECs formed a monolayer by $5{\sim}6$ days after plating and showed characteristics of whirling appearance. The TER increased until day 5 and decreased then. There was few immunoreaction with anti-GFAP, anti-GalC, anti-neurofilament 160/200 kD antibodies. So the contamination of astrocyte, oligodendrocyte, and neuron. could be ruled out.. Immunoreaction to vWF antigen was widespread througout the cytoplasm as Weibel-Palade granule. Immunoreaction to tight junction proteins, i.e. occludin, ZO-1, and ZO-2 was seen at cell contact. In summary, RBMECs isolated and cultured showed morphological, immunohistochemical and electrical characteristics of blood-brain barrier (BBB). The in vitro BBB model can be used in studying characteristics of in vivo BBB.

• Tuberculosis and Respiratory Diseases
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• v.52 no.2
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• pp.186-191
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• 2002

A malignant fibrous histiocytoma is a malignant soft tissue neoplasm that occurs frequently in the metaphyseal ends of the long bones of adults. The lung is a common site for metastasis but it is a rare site for a primary malignant fibrous histiocytoma. Here we report a case of a primary malignant fibrous histiocytoma of the lung. The patient was a 53-year-old man who presented with a moderate amount of a left pleural effusion and an illdefined mass in the left lower lobe on a chest radiograph and a local invasion to the left 10th and 11th rib on chest CT. Under the strong suspicion of lung cancer with a pleural invasion, a serial diagnostic thoracentesis was performed. The cytologic examination of the pleural effusion revealed no malignant cells. Consequently, a thoracoscopic pleural biopsy was performed. The histological examination revealed slender spindle cells and scattered epitheloid cells arranged in a vague storiform or a whirling pattern. Immunohistochemicaily, the tumor cells tested positive for vimentin and negative for cytokeratin, desmin, CD 34 and PAS. These features were consistent with a malignant fibrous histiocytoma. This case is an unusual addition to the small number of published reports on a primary malignant fibrous histiocytoma of the lung.

• (The) Research of the performance art and culture
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• no.42
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• pp.233-256
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• 2021

The purpose of this article is to understand the characteristics and meanings of the Hwanghae-do Gutchum, or shamanic ritual dance. First, the characteristics of the Hwanghae-do Gutchum are summarized as follows. The regular dances that appear in all pieces of Gutgeori or the tune of Gut of the Hwanghae-do Gutchum feature Geosangchum, followed by domu and heojeonmu in the sequential order. The accompaniment rhythms are Geosang rhythm, Chum rhythm, and Yeonpung rhythm. The dance featuring mugu, or shaman implements held on shaman's hand as part of the Hwanghae-do Gutchum, which symbolizes the characteristics of deities, is the same as domu aligned with the dance rhythm and the whirling dance aligned with the Yeonpung rhythm. The name of mugu, mubok (shaman clothing) and/or deities may be used as the name of Gutchum but there is no originality of Gutchum. The Beokgu Chum and Samhyeon Chum as part of the Hwanghae-do Gutchum use Beockgu Jangdan and Samhyeon Jangdan, which deserves to have their originality acknowledged. Hwanghae-do Gutchum is closely related to the rhythm. The harmony of janggu player and a female shaman is essential in practicing the Hwanghae-do Gut. If a janggu player fails to perform to properly support the gut practice of a female shaman, the shaman is not able to proceed with a smooth practice and causes confusion. On the other hand, if the gut performance of a female shaman fails to catch up with the performance of janggu, the gut becomes plain and simple at best. Janggu is the single most important element that determines the success or failure of the Hwanghae-do Gutchum. A female shaman takes the harmony and collaboration with a janggu player so seriously that she is willing to reschedule the practice of gut if its schedule does not match that of the janggu player. The Hwanghae-do Gutchum is largely dependent on gyeolrye. However, the difference between the chum and the rhythm caused by gyeolrye has disappeared due to the intangible cultural assets. That is, designating an intangible cultural asset has resulted in eliminating all distinctive characteristics of Hwanghae-do Gutchum. With the distinction of gyeolrye becoming vague, they have lost interest in the genealogy of gut they have learned. It is no longer gyeolrye but the intangible cultural property system that serves as an important factor to distinguish chums.