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

• Journal of Korean Academy of Nursing Administration
• /
• v.3 no.2
• /
• pp.41-59
• /
• 1997

This study surveyed nurses' value of reward and recognition level of organizational reward, and measured the fit of both. It also looked into the relationship between the reward fit and attitude of nurses toward their job and organization (job involvement${\cdot}$organizational commitment). It was planned to suggest the alternative of a future reward system. The sample consisted of 625 nurses of 8 private University Hospitals. Data for this study was collected from Mar. 25 to Apr. 17 by structured questionnaire. This study examined the differences of nurses' value of reward by their demographic characteristics, and looked into the relationship between the reward fit and job involvement${\cdot}$organizational commitment. Four instruments and a demographic questionnair were used to collect the data. Developed for myself and repaired by panel of judges, the value of reward scale and organizational reward scale consisted of 34 items on five points Likert-type scale. Developed by Kanungo and repaired by panel of judges, the job involvement scale measured overall job involvement on 7 items. The organizational commitment scale was developed by Mowday et al and repaired by panel of judges on 10 items. The data was analyzed by frequency, percentage, ranking, one-way ANOVA, Pearson's correlation coefficient, Chronbach alpha coefficient, t-test, SNK test, factor analysis with SPSS/PC+ progra,.Major findings are as follows 1. The mean of nurses' value of reward is 4.2435 and job content rewards are seen as the most important(M=4.5532). The following orders are seen as follows; financial rewards(M=4.4181), human realtion rewards(M=4.4130), establishment ${\cdot}$ facilities rewards(M=4.1632), professional rewards(M=4.1117), social status or prestige rewards(M=3.9228), career rewards(M=3.8816). Of 34 indivisual reward factors, the retainment allowance is seen to be thought of as the most important thing. 2. The mean of nurses' actual reward is 2.6035. The actual reward responded to the most extremely offered is job content rewards. The following orders are seen as follows ; human relation rewards(M=2.9420), financial rewards(M=2.7682), professional rewards(M=2.4601), social status or prestige rewards(M=2.3696), career rewards(M=2.3466), establishment ${\cdot}$ facilities rewards(M=1.9364). Of 34 indivisual reward factors, medical insurance benefits are felt to be most extremely offered. 3. The mean of fit of reward is -1.6874 and that means actual reward doesn't egual the value of the reward. What is offered mostly to nurses' value of reward is human relation rewards. The following orders are seen as follows; job content rewards(M=-1.5938), career rewards(M=-1.6381), social status of prestige rewards(M=-1.6382), financial rewards(M=-1.6836), professional rewards(M=-1.6854), establishment${\cdot}$facilities rewards(M=-2.3130). Of 34 indivisual factors, the item of fered most closely to nurses' value of reward is seen as the participation in educational programs at the nursing department of the hospital. 4. The mean of nurses' job involvement is 3.1987 and SD is 0.5667. 5. The mean of murses' organizational commitment is 2.9348 and SD is 0.6124, that is seen as a little lower than job involvement. 6. Significant value of reward differences were found among nurses by their demographic characteristics such as married status, tenure, academic career. 7. The fit of reward was significant related to job involvement and organizational commitment. When generalizing the result of this study, the value of reward, which nurses consider important and appropriate offers a reward that corresponds to the nurses' value of reward. This increases nurses' job and organization devotion further, as well as hospital effectiveness. It appears that nurses have recognized that the present reward offered in hospitals doesn't come up to their expectations so I think it is urgent to plan and perform the new reward system which is in accord with the nurses' reward fit.

• Journal of Oral Medicine and Pain
• /
• v.34 no.4
• /
• pp.371-377
• /
• 2009

Objectives: The aim of this study was to evaluate the differences in the polysomnography data between positional and non-positional obstructive sleep apnea (OSA) patients. Methods: Forty-seven patients diagnosed with OSA were evaluated using full night polysomnography. According to the criteria of Cartwright et al., the patients were classified into two groups with 37 positional (supine apnea-hypopnea index [AHI] $\geq$ 2x's the lateral AHI) and 10 non-positional (supine AHI < 2x's the lateral AHI) OSA patients, and the differences of polysomnography data between the two groups were evaluated. Results: There were no significant differences in demographic variables (age, gender, and BMI), daytime sleepiness, overall AHI, total arousal index, and percent time of snoring between two groups. However, AHI, arousal index, and mean oxygen saturation ($SpO_2$) of the REM sleep stage were significantly more severe in the positional OSA group than the non-positional OSA group. Mean $SpO_2$ and the lowest $SpO_2$ during overall sleep stage were also significantly lower in the positional OSA group than the non-positional OSA group. Conclusions: Our results of differences in the polysomnography data of REM sleep stage suggest that non-positional OSA patients may have higher collapsibility of the oropharyngeal airway during sleep than positional OSA patients.

• Journal of Periodontal and Implant Science
• /
• v.26 no.2
• /
• pp.448-468
• /
• 1996

To maintain its functional integrity, bone is continuously remodelled by a process involving resorption by osteoeclasts and formation by osteoblasts, In order to respond to changes in the physical environment or to trauma with the relevant action, this process is strictly regulated by locally synthesized or systemic fators, Prostaglandin $E_2(PGE_2$) is perhaps one of the best studied factors, having been known to affect bone cell function for several decades.$PGE_2$ has both anabolic and catabolic activities. Excess of $PGE_2$ has been implicated in a number of pathological states associated with bone loss in a number of chronic inflammatory conditions such as periodontal disease and rheumatoid arthritis. $PGE_2$ and other arachidonic acid metabolites have been shown to be potent stimulators of osteoclastic bone resorption in organ culture. The anabolic effects of $PGE_2$ were first noticed when an increase in periosteal woven bone formation was seen after the infusion of $PGE_2$ into infants in order to prevent closure of the ductus arteriosus. The cellular basis for the catabolic actions of $PGE_2$ has been well characterized. $PGE_2$increases osteoclast recruitment in bone marrow cell cultures. Also $PGE_2$ has a direct action on osteoclast serving to inhibit activity and can also indirectly activate osteoclast via other cells in the vicinity, presumably osteoblast. The cellular mechanisms for the anabolic actions of $PGE_2$ are not nearly so well understood. The purpose of this paper was to study the effects of $PGE_2$ and dibutyl(DB)cAMP on osteoblastic clone MC3T3El cells and on the generation of osteoclasts from their precursor cells. The effect of $PGE_2$ and DBcAMP on the induction of alkaline phoaphatase(AlP) was investigated in osteoblastic clone MC3T3El cells cultured in medium containing 0.4% fetal bovine serum. $PGE_2$ and DBcAMP stimulated ALP activity and MTT assay in the cells in a dose-dependent manner at concentrations of lO-SOOng/ml. Cycloheximide, protein synthesis inhibitor, inhibited the stimulative effect of $PGE_2$ and DBcAMP on ALP activity in the cells. $PGE_2$also increased the intracellular cAMP content in a dose-dependent fashion with a maximal effect at 500ng/ml. The effect of $PGE_2$ on the generation of osteoclasts was investigated in a coculture system of mouse bone marrow cells with primary osteoblastic cells cultured in media containing 10% fetal bovine serum.After cultures, staining for tartrate-resistant acid phosphatase(TRAP)-marker enzyme of osteoclast was performed. The TRAP(+) multinucleated cells(MNCs), which have 3 or more nuclei, were counted. More TRAP(+) MNCs were formed in coculture system than in control group. $PGE_2(10^{-5}10^{-6}M)$ stimulated the formation of osteoclast cells from mouse bone marrow cells in culture. $PGE_2(10^{-6}M)$ stimulated the formation of osteoclast cells from mouse bone marrow cells in coculture of osteoblastic clone MC3T3E1 cells This results suggest that $PGE_2$ stimulates the differentiation of osteoblasts and generation of osteoclast, and are involved in bone formation, as well as in bone resorption.

• Sleep Medicine and Psychophysiology
• /
• v.8 no.1
• /
• pp.30-36
• /
• 2001

Object: Diurnal variation is included in the diagnostic criteria of the major depressive disorder, melancholic specifier. But there has been controversy over whether diurnal variation is an unique depressive symptoms or a symptom related to a change of sleep patterns, or that of another mechanism, when the previous studies are reviewed. We investigated the existence of diurnal variation according to the subtype of depression and whether diurnal variation is charateristic of melancholic depression or not. We also compared sleep variables according to the existence of diurnal variation. Method: We examined diurnal variation, sleep patterns, severity of depression using the Visual Analogue Mood Scale, Pittsburgh Sleep Quality Index, and Hamilton Depression Rating Scale. Patients recorded their mood state on the Visual Analogue Mood Scale twice a day, morning and evening, for diurnal variation. We divided depressive patients into two groups,-diurnal variation group and nondiurnal variation group,-and compared the mood and sleep variables using SPSS. Results: The frequency of diurnal variation is not significantly different among the subtypes of depression. Significant differences between the diurnal variation group and the nondiurnal variation group existed in middle insomnia and sleep time (p<0.05). In melancholic type, al significant difference between the diurnal variation group and the nondiurnal variation group was noticed in PSQI total, sleep latency, sleep disturbances, daytime dysfunction as well as middle insomnia and sleep time (p<0.05). Conclusions: Diurnal variation existed in other types of depression as well as melancholic type. The results showed that diurnal variation was not a specific symptom of melancholic type, and existence of diurnal variation might be related to sleep patterns.

• Journal of Korean Home Economics Education Association
• /
• v.18 no.3 s.41
• /
• pp.41-60
• /
• 2006

The system of teaching culinary practice needs drastic modification to catch up with dietary life and education curriculum changes. To reflect such changes, it is necessary to instill a strong will and interest as well as educational environment improvement in teachers. In this sense, this study researched the teachers' stages of concerns, levels of use, innovation configuration, and intervention demands, based on the CBAM(Concerns Based Adoption Method) developed by Hord et. al. For the survey, 500 questionnaires sent by mail and 187 were analyzed by SPSS/win 10.0 program. The results are summarized as follows. 1) The teachers stages of concerns on culinary practice is assessed to be in the lowest level of perceptual stage, which indicates a state of indifference. 2) In terms of the levels of use, routine use was the highest, followed by refinement use, integrated use, research use, and reinvent use in descending order. Mechanical use posted the lowest level. Even though the stages of concern showed the beginning stage, the Level of use was relatively high. 3) About the innovation configuration, approximately 30% of the teachers were not accomodate the culinary practice referred to the 7th National Education Curriculum. 4) According to the intervention demands on culinary practice education, it was found that teachers generally wanted more interventions in every component. Among the intervention components, the highest demand was on the support for facility. Demand on the financing is the second highest. Teachers in the level of routine use demanded more information and materials supply and individual encouragement, but teachers in the level of preparation needed study opportunity for training on operation skills more.

• Korean Chemical Engineering Research
• /
• v.46 no.5
• /
• pp.994-1001
• /
• 2008

Freundlich isothermal adsorption parameters, applicable to such biofilter-model as process-lumping model(Lim's model), for sterilized granular activated carbon(GAC), sterilized compost and sterilized equal volume mixture of GAC and compost were obtained and were compared each other, assuming that adsorbents are enclosed by water layer, in order to construct robust process-lumping biofilter model effective for wide-range of hydrophilic volatile organic compounds(VOC). In this investigation 0.04, 0.08, 0.12, 0.16, 0.2, 0.4, 0.8 and 1.0ml of ethanol were added to three kinds of adsorbent-media and were placed at $30^{\circ}{\cdots}$ under the wet condition of the media, which was the same as biofilter operating condition, until the adsorption reached the condition of equilibrium before each adsorbed amount of ethanol was obtained. Then adsorption capacity parameters(K) and adsorption exponents of Freundlich adsorption isotherm equation, which simulates the adsorbed amount of ethanol equilibrated with the ethanol concentration of the condensed water in the pore of the media, were constructed for sterilized granular activated carbon(GAC), sterilized compost and sterilized equal volume mixture of GAC and compost as (0.7566 and $5.070{\times}10^{-7}mg-ethanol/mgmedia/(mg-ethanol/m^3)^{0.7566}$), (0.8827 and $1.000{\times}10^{-8}mg-ethanol/mgmedia/(mg-ethanol/m^3)^{0.8827}$) and (0.5688 and $5.243{\times}10^{-6}mg-ethanol/mgmedia/(mg-ethanol/m^3)^{0.5688}$), respectively. These Freundlich isothermal adsorption parameters were applicable to the adsorption characteristics of biofilter media enclosed with bio-layer. The order of magnitude of the ratio of ethanol-air/water partition coefficient and toluene-air/water partition coefficient was almost consistent to that of ethanol-adsorbed amounts in this experiment with compost and in the investigation of Delhomenie et al. on toluene-adsorption to wet compost.

• Korean Chemical Engineering Research
• /
• v.50 no.2
• /
• pp.365-370
• /
• 2012

In this study, Economic analysis of supercritical coal-fired power plant with $CO_2$ capture process was performed. For this purpose, chemical absorption method using amine solvent, which is commercially available and most suitable for existing thermal power plant, was studied. For the evaluation of the economic analysis of coal-fired power plant with post-combustion $CO_2$ capture process in Korea, energy penalty after $CO_2$ capture was calculated using the power equivalent factor suggested by Bolland et al. And the overnight cost of power plant (or cost of plant construction) and the operation cost reported by the IEA (International Energy Agency) were used. Based on chemical absorption method using a amine solvent and 3.31 GJ/$tonCO_2$ as a regeneration energy in the stripper, the net power efficiency was reduced from 41.0% (without $CO_2$ capture) to 31.6% (with $CO_2$ capture) and the levelized cost of electricity was increased from 45.5 USD/MWh (Reference case, without $CO_2$ capture) to 73.9 USD/MWh (With $CO_2$ capture) and the cost of $CO_2$ avoided was estimated as 41.3 USD/$tonCO_2$.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.6 no.1
• /
• pp.109-132
• /
• 2011

While the resource-based view suggests that a firm's competitive advantage rests on a set of valuable, rare and inimitable resources more generally (Barney, 1991), research in new firms has more specially indicated a link between initial resources and early performance and survival (Bruderl and Schussler, 1990; Fichman and Levinthal, 1991; Carroll et al., 1996). The RBV primarily focuses on the particular resources, and their characteristics, that provide the potential for advantage (Conner, 1991). Yet in order to realize this advantage, organizations must not only develop their resources, but also effectively deploy them (Admit and Shoemaker, 1993). This suggests that advantage from resources may reside in both the input (resource development) side and the output (resource deployment) side. This research looks at venture survival as a function of both the resources a firm owns, and the resources it can access from others. We focus more specifically on technology resources, which are among a technology-based firm's most critical resources (Itami, 1987). In addition, technological knowledge can contribute a large portion of the value of a firm's products (Goodman and Lawless, 1994). We look at both the input and output side: the pool of technology resources that serve as an input to a firm's activities, and the market that values and purchases the output of this activity. We take an international perspective, examining whether resources explain internationalization on the input and output side, and in turn, whether this internationalization can explain survival. We explore three sets of questions. First, can survival in entrepreneurial firms be explained as a function of the resources a firm owns, and beyond that, to those the firm can access, and still further, to those the firm can access internationally? Second, do resources explain internationalization on both the input and output side? And finally, does internationalization explain survival? Implications for theory include extending the RBV to not only include a firm's resources, but its access to the resources of other entities. In addition, examining internationalization on both the input and output side enables us to understand not just the potential advantage of resources, but the manner in which they are deployed as a source of advantage. This research also contributes to the literature on international entrepreneurship by examining whether internationalization can explain survival for early stage firms. For practitioners, this research will provide insights on the importance of building alliances and, in so doing, broadening an organization's perspective about the technology resources available to the firm on the input side. The study will also inform practitioners about the value of maximizing the market for a firm's valuable resources. In addition, this research provides an extraordinary opportunity to access a large, comprehensive, and longitudinal dataset on technology-based ventures in Korea.

• Journal of Yeungnam Medical Science
• /
• v.2 no.1
• /
• pp.95-102
• /
• 1985

This report offers descriptive data about the drugs utilized in out patient department (OPD) of Yeungnam University Hospital (YUH) in the period of march to august in 1985. The data in this report were produced by the computerized totalization of the number of mentions of individual drugs included in the prescriptions. The 100 drug entries that were most frequently recorded are listed in rank order. The listing is arbiturarily restricted to the drugs that were prescribed as single preparations, the drugs of basis of compound preparations and the drugs of adjuvent or corrective of compound preparations that have significant therapeutic effects either by generic names. And in addition, the listing also involves the compound preparations used in relatively large frequency, and the individual components of which have the unique pharmacological actions each other by proprietary names. And all routes of administrations were allowed. The 10 drugs most frequently named are diazepam, aluminum compounds, acetaminophen, isoniazid, metoclopramide, $polaramine^{(R)}$, carboxymethylcystem, ephedrine, codeine and caroverine in order. The 521,855 drug mentions listed as above are described by the chief therapeutic usage that each is intended to apply generally. The drugs which account the largest proportion of total mentions were those acting on the central nervous system (20.57%), including tranquilhzers and sedative hypnotics (11.71%), analgesic antipyretics (5.55%), antidepressants (2.15%) etc. Gastrointestinal drugs and smooth muscle preparations (18.64%) included antacids and anti-ulcer drugs (9.24%), antiemetics (3.57%), spasmolytics (3.14%) and others. Respiratory drugs (16.11%) included expectorants and cough preparations (10.99%) and bronchodilators (5.12%). Chemotherapeutic agents (15.12%) included the antiTbc drugs (7.09%) most frequently, and the penicillins (3.33%) accounted the largest proportion among the antibiotics. Cardiovascular drugs (5.64%) included cardiac drugs and coronary vasodilator (4.12%) and antihypertensives and vasodilators (1.06%). And anti-inflammatory drugs (4.33%), vitamins of single preparations (3.76%), hormones and their antagonists (3.29%), common cold preparations (3.12%), diuretics (2.81%), drugs supporting liver function (2.02%), drugs affecting autonomic nervous system(1.89%) including anti-glaucomas, atropine and cerebral vasodilators, antihistamine drugs (1.02%) and disinfectants (0.74%) were following in order. The data in this report were compared to those reported by H. Koch, et al. in United States (US), 1981 as "Drugs Most Frequently Used in Office Practice:National Ambulatory Medical Case Survey, 1981." Cardiovascular drugs prescribed in YUH were much less in proportion than in US (10.56%), but gastrointestinal drugs accounted the larger proportion than in US (3.72%). Expectorants and cough preparations in YUH also accounted the larger proportion than in US (2.74%). In conclusion, in the period of march to august, 1985, OPD of YUH prescribed the CNS drugs including diazepam most frequently, and gastrointestinal, repiratory and chemotherapeutic drugs in next orders. It is supposed that the eating habits of Koreans and a unique atmospheric condition in Taegu as a basin were some important factors that affected the proportions of drugs acting on gastrointestinal and respiratory tracts.