• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.91-93
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• 2003

A comprehensive numerical study is carried out to investigate for the understanding of the flow evolution and flame development in a supersonic combustor with normal injection of ncumally injecting hydrogen in airsupersonic flows. The formulation treats the complete conservation equations of mass, momentum, energy, and species concentration for a multi-component chemically reacting system. For the numerical simulation of supersonic combustion, multi-species Navier-Stokes equations and detailed chemistry of H2-Air is considered. It also accommodates a finite-rate chemical kinetics mechanism of hydrogen-air combustion GRI-Mech. 2.11[1], which consists of nine species and twenty-five reaction steps. Turbulence closure is achieved by means of a k-two-equation model (2). The governing equations are spatially discretized using a finite-volume approach, and temporally integrated by means of a second-order accurate implicit scheme (3-5).The supersonic combustor consists of a flat channel of 10 cm height and a fuel-injection slit of 0.1 cm width located at 10 cm downstream of the inlet. A cavity of 5 cm height and 20 cm width is installed at 15 cm downstream of the injection slit. A total of 936160 grids are used for the main-combustor flow passage, and 159161 grids for the cavity. The grids are clustered in the flow direction near the fuel injector and cavity, as well as in the vertical direction near the bottom wall. The no-slip and adiabatic conditions are assumed throughout the entire wall boundary. As a specific example, the inflow Mach number is assumed to be 3, and the temperature and pressure are 600 K and 0.1 MPa, respectively. Gaseous hydrogen at a temperature of 151.5 K is injected normal to the wall from a choked injector.A series of calculations were carried out by varying the fuel injection pressure from 0.5 to 1.5MPa. This amounts to changing the fuel mass flow rate or the overall equivalence ratio for different operating regimes. Figure 1 shows the instantaneous temperature fields in the supersonic combustor at four different conditions. The dark blue region represents the hot burned gases. At the fuel injection pressure of 0.5 MPa, the flame is stably anchored, but the flow field exhibits a high-amplitude oscillation. At the fuel injection pressure of 1.0 MPa, the Mach reflection occurs ahead of the injector. The interaction between the incoming air and the injection flow becomes much more complex, and the fuel/air mixing is strongly enhanced. The Mach reflection oscillates and results in a strong fluctuation in the combustor wall pressure. At the fuel injection pressure of 1.5MPa, the flow inside the combustor becomes nearly choked and the Mach reflection is displaced forward. The leading shock wave moves slowly toward the inlet, and eventually causes the combustor-upstart due to the thermal choking. The cavity appears to play a secondary role in driving the flow unsteadiness, in spite of its influence on the fuel/air mixing and flame evolution. Further investigation is necessary on this issue. The present study features detailed resolution of the flow and flame dynamics in the combustor, which was not typically available in most of the previous works. In particular, the oscillatory flow characteristics are captured at a scale sufficient to identify the underlying physical mechanisms. Much of the flow unsteadiness is not related to the cavity, but rather to the intrinsic unsteadiness in the flowfield, as also shown experimentally by Ben-Yakar et al. [6], The interactions between the unsteady flow and flame evolution may cause a large excursion of flow oscillation. The work appears to be the first of its kind in the numerical study of combustion oscillations in a supersonic combustor, although a similar phenomenon was previously reported experimentally. A more comprehensive discussion will be given in the final paper presented at the colloquium.

• Management & Information Systems Review
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• v.36 no.3
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• pp.131-150
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• 2017

The purpose of this study is to observe the spread pattern of open source software (OSS) while establishing relations with surrounding actors during its operation period. In order to investigate the change pattern of participants in the OSS, we use a netnography on the basis of online data, which can trace the change patterns of the OSS depending on the passage of time. For this, the cases of three OSSs (e.g. jQuery, MooTools, and YUI), which are JavaScript frameworks, were compared, and the corresponding data were collected from the open application programming interface (API) of GitHub as well as blog and web searches. This research utilizes the translation process of the actor-network theory to categorize the stages of the change patterns on the OSS translation process. In the project commencement stage, we identified the type of three different OSS-related actors and defined associated relationships among them. The period, when a master commences a project at first, is refined through the course for the maintenance of source codes with persons concerned (i.e. project growth stage). Thereafter, the period when the users have gone through the observation and learning period by being exposed to promotion activities and codes usage respectively, and becoming to active participants, is regarded as the 'leap of participants' stage. Our results emphasize the importance of promotion processes in participants' selection of the OSS for participation and confirm the crowding-out effect that the rapid speed of OSS development retarded the emergence of participants.

• Korean Journal of Weed Science
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• v.7 no.1
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• pp.90-97
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• 1987

An attempt was done at the Yeongnam Crop Experiment Station in 1986-'87 to obtain herbicide tolerant variant through cell culture. Immatured rice grain was more rapidly and efficiently formed callus in dehulled rice culture method for both rice cultivar types, Tongil type (Indica/Japonica) and Japonica-type. However, Japonica-type cultivar was generally superior than Tongil-type Cultivar in callus formation. Expression rate of herbicide tolerant variant varied depending upon rice cultivar, plant species and herbicide properties. In case of Nagdongbyeo (Japonica) at the first subculture, 46.3% of total callus pieces appeared as herbicide tolerant variant in herbicide media of CGA142464 and followed by NC-311 (11.6%), Butachlor (7.5%), 2.4-D (2.1%), Quinclorac (0.89%), and Propanil (0.25%), in order. This degree of appearance of herbicide tolerant variants rapidly increased as passage of subculture was advanced. Herbicide tolerant callus hardly regenerated as normal plant even though large variations exhibited among culture media.

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.33-43
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• 1968

Histamine, 0.5 mg as histamine base in 4 ml of normal saline solution, was injected into rabbits anesthetized with nembutal and the mean blood pressure was kept in the range of $52{\sim}80\;mmHg$ for over one hour by supplemental additions. Following the injection of the test substances, 300 mg of urea and 200 mg of antipyrine intravenously, serial blood samples were obtained from the femoral artery and the internal jugular vein at $0.5{\sim}3$ minutes interval. The decreasing patterns in the concentrations of arterial and venous blood plasma samples were compared with each other. The ratio of the concentration of brain tissue to that of the final arterial plasma was also studied. By these measures the degrees of penetration of the test substances in the brain in the control and in the histamine treated rabbits were observed. The concentrations of antipyrine and urea in the arterial blood plasma were decreasing exponentially with respect to the time elapsed. The venous concentrations were anticipated to increase initially and to cross the arterial concentration curve in the point of equlibrium between the plasma and the tissue. On the contrary to the expectation venous concentration also revealed the decreasing tendency similar to that of arterial plasma. The similarity between these two curves, arterial and venous, would be atributable to the fact that the cerebral blood flow rate was large enough and the rising phase in the venous concentration curve was instantly over before serial blood samples were taken. Inspite of some similarity in the decreasing tedency in both concentration curves there were appreciable discrepancies between the arterial and venous plasma which would reflect the situation far from the equlibria among several compartments in the brain. Changes in plasma potassium levels caused by the injection of histamine or bleeding were observed, too. Using 8 rabbits as the control and 12 rabbits for the histamine treated group following results were obtained: 1. Both of the concentration curves, arterial and venous, declined rapidly at_first and slowly later on and approached same equilibrium concentration with the passage of time after a single injection. The time at which attained the same concentration was $2.0{\pm}0.54\;min.$ in the control and $4.3{\pm}1.92\;min.$ in the histamine treated group with respect to antipyrine. On the other hand in the case of urea they were $2.4{\pm}0.59\;min.$ in the control and $4.4{\pm}1.31\;min.$ in the histamine group, respectively. In the histamine treated group enlarged spaces for distribution of test substances were postulated. 2. The concentration of antipyrine in the brain tissue water revealed no significant differences between the control and experimental groups, showing $212{\pm}40.2\;mg/l$ in the control and $206{\pm}64.1\;mg/l$ in the histamine treated group. On the other hand urea revealed higher value in the histamine treated group than in the control, showing an enhanced penetration of urea into the tissue after injection of histamine. Urea concentration in the brain water was $32.3{\pm}3.36\;mg%$ in the control and $39.2{\pm}4.25\;mg%$ in the histamine treated group. 3. The distribution ratio of antipyrine in the brain tissue was very close to unity in the histamine treated animals as well as in the control. 4. The average of the distribution ratio of urea in the control animals was 0.77 and it showed the presence of blood-brain barrier with regard to urea. However in the histamine treated animals the distribution ratios climbed up to 0.86 and they were closer to unity than in the control animals. Out of 12 cases 5 were greater than 0.9 and 8 exceeded 0.85. It appeared that histamine enhanced the penetration of urea through the barrier. 5. Histamine injection and or hemorrhage caused an elevation of the concentration of potassium in plasma. In the event that histamine and hemorrhage were applied together the elevation of potassium exceed the elevation seen at the histamine alone. There was no evidence that the leakage of potassium from the brain tissue was dominant in comparison with the general leakage from the whole body.

• The Korean Journal of Archival Studies
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• no.65
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• pp.365-396
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• 2020

I examined the archival basis of two historians who wrote history books with the same title of 'History'; Simaqian of ancient China and Herodotus of Halikarnassos. I examined a prejudice to these two history books, a misunderstanding of them as an imagination rather than a history. How can an imagination become a history? First, I explained the common characteristics found in their compilation and writing of 'History.' Simaqian and Herodotus did their field-works in historical sites, gathered oral-histories, and arranged archives they collected. These two historians heavily engaged in archival works in terms of verifying authenticity and reliability of their sources on the basis of historical empiricism. There are some misunderstanding on their archival endeavor and on the very nature of archives and historical studies as empirical studies. Furthermore, this misunderstanding regarding them as literature came from a confusion over the concept of literature. The creativity of literature is not equal to the "fictitiousness" of history despite historical works sometimes may give us an impression by the way of describing and providing insight into a certain event(s) and a person(s). As Herodotus said, a recognition of the differences of each race and human is a departure of historical archiving of the valuable experiences of human-beings. By doing so, natural results of archival behaviors, preservation of the records, and consistent inquiry of historian-archivists become a humanistic passage overcoming the current wrong trends of historical studies confined to a narrow nation-history.

• Journal of Korean Society of Forest Science
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• v.7 no.1
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• pp.3-7
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• 1968

The Capacity of wood to absorb water is very important as the basis data for wood industry, particularly in preservatives impregnation, manufacturing of improved wood, selection of packing boards, etc. In this study differences in Water absorbing Capacity of wood by structual section, water soaking time were investigated. (1) The species used in this investigation were Larix olgensis Henry Var. Koreana Nakai and Juglans mandshurica Max., and dimension of these testing wood block was $30{\times}30{\times}100cm$; and these were soaked in fresh water of $25{\pm}1^{\circ}C$ for 8.5day and 0.5 day, before measurement. (2) The result showed that the water absorption by cross sections was greater than by either radial or tangential section and there were no differences between radial and tangential section. (3) The water absorption of Juglans mandshurica Max. which has the relatively low specific gravity was greater than Larix olgensis Henry Var. Koreana Nakai which has generally high specific gravity. (4) The result showed an increase in the absorbed water with increase in the length of soaking time. However the water absorption rate during the early period of soaking was very high and thereafter the rate decreased with passage of time. More than a half of the total water absorption was achieved during the first 2 days approximately. (5) The relationships between the length of the soaking-time and water absorption were found to be as follows : Larix olgensis Henry Var. Koreana Nakai Cross section : $y=111.1{\times}^{0.6516}$ radial section : $y=32.2{\times}^{0.5146}$ tangential section : $y=36.5{\times}^{0.5112}$ Juglans mandshurica Max. Cross section : $y=216.1{\times}^{0.5914}$ radial section : $y=27.9{\times}^{0.5832}$ tangential section : $y=50.9{\times}^{0.4769}$ Where : y is amount of water absorption ($mg/cm^2$) x is water-soaking time (days).

• Journal of the Korea Society of Computer and Information
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• v.24 no.11
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• pp.209-218
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• 2019

The purpose of this study is to longitudinally analyze the relationship between parenting effectiveness of parents of multicultural families and self-esteem and achievement motivation of multicultural adolescents. The study used the data of Multi-cultural Adolescent Panel Survey (MAPS). Of the six years of data from the 1st survey (elementary grade 4 students) in 2011 to the 6th survey ($3^{rd}$ year middle school students) in 2016, this study employed and analyzed the data from year 2012 ($2^{nd}$ survey, fifth graders), year 2014 ($4^{th}$ survey, 1st year middle school students), and year 2016 ($6^{th}$ survey, $3^{rd}$ year middle school students). The results of applying the Autoregressive Cross-lagged Model to examine the longitudinal relationship between parenting effectiveness of multicultural families and self-esteem and achievement motivation of multicultural adolescents are as follows. First, parenting effectiveness of parents of multicultural families, and self-esteem of multicultural adolescents, and autoregressive effects of achievement motivation were found to have a positive (+) effect with the passage of time. Second, the parenting effectiveness of parents of multicultural families at the previous time was found to have a significant positive (+) effect on the cross-lagged effect on self-esteem and achievement motivation of multicultural adolescents at a later time. Third, the self-esteem of multicultural adolescents at the previous time at the previous time was found to have a significant effect in the positive (+) direction on the cross-lagged effect affecting achievement motivation of multicultural adolescents at a later time. Fourth, it was found that the cross-lagged effect of the parenting effectiveness of parents of multicultural families on achievement motivation of multicultural adolescents was greater than the cross-lagged effect of self-esteem on achievement motivation of multicultural adolescents. This study is meaningful in that the longitudinal data are used to verify the causal orientation between three variables over time to examine the relationship between parenting effectiveness of parents of multicultural families and self-esteem and achievement motivation of multicultural adolescents.

• Korean Journal of Heritage: History & Science
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• v.43 no.3
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• pp.242-281
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• 2010

There are a large number of Buddhist cultural relics in Mt. Namsan. The cultural relics carry the spirit of people of Shila who dream of Buddhist Elysium and the establishment of Buddhist nation. In the valley and the top of the mountain and on various rock cliff, stone statues of Buddha and stone pagodas stand in harmony with nature. For that reason, Mt. Namsan is called an open-air museum. And it played an important role in establishing 'The UNESCO World Heritage' status for Gyeongdju in December 2000. But sadly, there are many stone relics that have eroded away and damaged from collapsing in the passage of time. The seated stone statue of Buddha in Samreoung valley of Mt. Namsan is one of them. It was created between the 8th and 9th century, and restored without much care nor extensive historical research in 1923. As a result, The face of the Buddha remained with concrete mortar and its nimbus fallen backward and destroyed. Therefore, restoration and repair as well as creation of a statue environment for the statue were urgent. So we immediately started in restoration and repair. First, through the archaeological excavation around the stone Buddha, we carried the stone Buddha on the original position. In order to restore the statues to its original glory created by the Unified Shila Dynasty, we created a restoration plan in corporation with art historians and historians, then restored the jaw and the damage nimbus. Second, we made the weathering & damage map of the stone Buddha. In order to prevent second damage, we cleaned the surface of contaminants with distilled water. Third, we studied restoration method to prevent artificial damage. We recreated parts of his face and halo. Then each parts of the statue were restored to their original position. In the whole process of restoration, we tried to use traditional techniques.

• Journal of Astronomy and Space Sciences
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• v.36 no.1
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• pp.21-33
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• 2019

This paper focuses on the interpretation of radiation fluxes from active galactic nuclei. The advantage of positron annihilation spectroscopy over other methods of spectral diagnostics of active galactic nuclei (therefore AGN) is demonstrated. A relationship between regular and random components in both bolometric and spectral composition of fluxes of quanta and particles generated in AGN is found. We consider their diffuse component separately and also detect radiative feedback after the passage of high-velocity cosmic rays and hard quanta through gas-and-dust aggregates surrounding massive black holes in AGN. The motion of relativistic positrons and electrons in such complex systems produces secondary radiation throughout the whole investigated region of active galactic nuclei in form of cylinder with radius R= 400-1000 pc and height H=200-400 pc, thus causing their visible luminescence across all spectral bands. We obtain radiation and electron energy distribution functions depending on the spatial distribution of the investigated bulk of matter in AGN. Radiation luminescence of the non-central part of AGN is a response to the effects of particles and quanta falling from its center created by atoms, molecules and dust of its diffuse component. The cross-sections for the single-photon annihilation of positrons of different energies with atoms in these active galactic nuclei are determined. For the first time we use the data on the change in chemical composition due to spallation reactions induced by high-energy particles. We establish or define more accurately how the energies of the incident positron, emitted ${\gamma}-quantum$ and recoiling nucleus correlate with the atomic number and weight of the target nucleus. For light elements, we provide detailed tables of all indicated parameters. A new criterion is proposed, based on the use of the ratio of the fluxes of ${\gamma}-quanta$ formed in one- and two-photon annihilation of positrons in a diffuse medium. It is concluded that, as is the case in young supernova remnants, the two-photon annihilation tends to occur in solid-state grains as a result of active loss of kinetic energy of positrons due to ionisation down to thermal energy of free electrons. The single-photon annihilation of positrons manifests itself in the gas component of active galactic nuclei. Such annihilation occurs as interaction between positrons and K-shell electrons; hence, it is suitable for identification of the chemical state of substances comprising the gas component of the investigated media. Specific physical media producing high fluxes of positrons are discussed; it allowed a significant reduction in the number of reaction channels generating positrons. We estimate the brightness distribution in the ${\gamma}-ray$ spectra of the gas-and-dust media through which positron fluxes travel with the energy range similar to that recorded by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) research module. Based on the results of our calculations, we analyse the reasons for such a high power of positrons to penetrate through gas-and-dust aggregates. The energy loss of positrons by ionisation is compared to the production of secondary positrons by high-energy cosmic rays in order to determine the depth of their penetration into gas-and-dust aggregations clustered in active galactic nuclei. The relationship between the energy of ${\gamma}-quanta$ emitted upon the single-photon annihilation and the energy of incident electrons is established. The obtained cross sections for positron interactions with bound electrons of the diffuse component of the non-central, peripheral AGN regions allowed us to obtain new spectroscopic characteristics of the atoms involved in single-photon annihilation.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.1
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• pp.33-52
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• 2022

The History and Culture Park and the Lee Kun-hee Donation Hall will be built in Songhyeon-dong, Seoul. Political games from the Joseon Dynasty to the present greatly influenced the historicity of Songhyeon-dong. However, place analysis was limited to changes in landowners and land uses rather than a historical context. Therefore, this study analyzed the context in which the placeness of Songhyeon-dong changed according to the emergence of cultural hegemony using the perspective of modern cultural geography and comparative history. As a result of the analysis, cultural hegemony in historical transitions, such as Sinocentrism, maritime expansion, civil revolutions, imperialism, nationalism, popular art, and neoliberalism, was found to have created new intellectuals in Bukchon, including Songhyeon-dong, and influenced social systems and spatial policies. In this social relations, the placeness of Songhyeon-dong changed as follows. First, the founding forces of Joseon created pine forests as Bibo Forests to invocate the permanence of the dynasty. In the late Joseon dynasty, it was an era of maritime expansion, and as Joseon's yeonhaeng increased, a garden for the Gyeonghwasejok, who enjoyed the culture of the Qing dynasty, was built. Although pine forests and gardens disappeared due to the development of housing complexes as the population soared during the Japanese colonial era, Cha Gyeong's landscape aesthetics, which harmonized artificial gardens and external nature, are worth reinterpreting in modern times. Second, the wave of modernization created a new school in Bukchon and a boarding house in Songhyeon-dong owned by a pro-Japanese faction. Angukdongcheon-gil, next to Songhyeon-dong, was where thinkers who promoted civil revolution and national self-determination exchanged ideas. Songhyeon-dong, the largest boarding house, served as a residence for students to participate in the March 1st Movement and was the cradle of the resulting culture of student movements. The appearance of the old road is preserved, so it is a significant part of the regeneration of walking in the historic city center, connecting Gwanghwamun-Bukchon-Insadong -Donhwamunro. Third, from the cultural rule of the Government General of Joseon to the Military Government, Songhyeon-dong acted as a passage to western culture with the Joseon Siksan Bank's cultural housing and staff accommodations at the U.S. Embassy. Ancient and contemporary art coexisted in the surrounding area, so the modern and contemporary art market was formed. The Lee Kun-hee Donation Hall is expected to form a cultural belt for citizens with the gallery, Bukchon Hanok Village, the Craft Museum, and the Modern Museum of Art. Discourses and challenges are needed to recreate the place in harmony with the forests, gardens, the street of citizens' birth, history and culture park, the art museum, and the surrounding walking network.