• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.1
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• pp.8-23
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• 1997

Steady and unsteady numerical simulations are conducted for the comparison with the experiments performed to investigate the ram accelerator flow field by using an expansion tube facility in Stanford University. Wavier-Stokes equations for chemically reacting flows are analyzed by fully implicit and time accurate numerical methods with Jachimowski's detailed chemistry model for hydrogen-air combustion involving 9 species and 19 reaction steps. Although the steady state numerical simulation shows a good agreement with the experimental schlieren and OH PLIF images for the case of $2H_2$＋$O_2$＋$17N_2$ fails in reproducing the combustion region behind the shock intersection point shown in the case of $2H_2$＋$O_2$＋$12N_2$ mixture. Therefore, an unsteady numerical simulation is conducted for this case and the result shows all the detailed flow stabilization process. From the result of unsteady numerical simulation, the experimental result seems to be an instantaneous state during the flow stabilization process. The combustion behind the shock intersection point is the result of a normal detonation formed by the intersection of strong oblique shocks that exist at early stage of the stabilization process. At final stage, the combustion region behind the shock intersection point disappears and the steady state result is retained. The time required for stabilization of the reacting flow in the model ram accelerator is found to be very long in comparison with the experimental test time.

• Analytical Science and Technology
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• v.6 no.5
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• pp.471-477
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• 1993

The novel macrocylic ligand {(4, 5):(13, 14)-dibenzo-6, 9, 12-trioxa-3, 15, 21, -triazabicyclo [15. 3. 1]heneicosa-(1, 17, 19)(18, 20, 21) triene: HDBPDA} was synthesized, and protonable constants of the ligand and the complex stability constants with alkali metals alkaline earth metals were determined. We evaluated the resolution factor(${\Delta}$) from equation that inducing from stability constants(pK). Also, this ligand was grafted on chloromethylated styrene-divinyl benzene(Merrifield resin) for HDBPDA, ion exchanger. Alkali and alkaline earth metal ions were separated using water by the column chromatography with this ion exchanger. Selectivity(${\alpha}$) and resolution(Rs) of alkali and alkaline earth metal ions were measured from the elution curves chromatogram. The selectivity and resolution values of the various ions calculated from the elution curves were compared with those abtained from pK values. The results were in a good agreement between tow methods. Ion exchange capacity of the resin were determined using the alkali and alkaline earth metal ions and pH dependence of capacity was also discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.82-92
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• 2019

The purpose of this study was to analyze the relationship and degree of agreement between the six types of Geometry Psychological Assessment (GEOPIA) and four functions of the Myers-Briggs Type Indicator (MBTI) personality test, and to investigate the appropriate level of vocational aptitude commonly recommended by each tool. A total of 377 adult men and women from Korea, aged between 19 and 70 years, were tested using GEOPIA and the MBTI. Cronbach's alpha was calculated to verify the validity and reliability of the measuring tools, and the mean and standard deviation of each variable were calculated. Also, a cross-sectional analysis was conducted to examine the relationship between GEOPIA and the MBTI. The results showed that Round/Triangle (RT) types, Round/Box (RB) types, Triangle/Box (TB) types and Box/Curve (BC) types among the GEOPIA personality types are highly related to MBTI's Sensing/Thinking (ST) types. GEOPIA RC types were related to Intuition/Feeling (NF) and Sensing/Feeling (SF) types, and TC types were highly related to Intuition/Thinking (NT) types. Based on the common characteristics of the two tests, the findings suggest appropriate levels of vocational aptitude. Through this research, it was confirmed that GEOPIA (a Korean psychology and personality test) can be used in counseling, coaching, and education, and above all, is a reliable tool for vocational psychological assessment to search for career aptitude.

• Journal of the Korea Society of Computer and Information
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• v.28 no.3
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• pp.197-208
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• 2023

The purpose of this study is to establish definitions on Metaverse and Metaverse literacy and to develop a framework for Metaverse literacy utilizing a Delphi study and in-depth interview methods with experts on Metaverse and digital, and future education. 9 experts participated in the Delphi study and 4 took part in the in-depth interview, and Delphi study data was collected via emails from January 12th to 17th and in-depth study data was gathered via zoom from March 1st to 19th in 2022. To establish the definition of Metaverse, 6 existing definitions were presented and ranked with calculated means of each definition, and additional comments were collected. To build the definition of Metaverse literacy, 1 existing definition was shown and calculated with the degree of agreement, and additional feedback was gathered. To develop a framework for Metaverse literacy, 12 sub-concepts were presented and ranked with calculated means of each concept. After applying feedback of the Delphi study, the authors re-established the definitions of Metaverse and Metaverse literacy, and re-develop the framework for Metaverse literacy. In the in-depth interview, feedback on these definitions and the framework was collected. After these processes, the definitions of Metaverse and Metaverse literacy were finalized, and the framework for Metaverse literacy was developed. Based on the results, implications and limitations of the study, and possible future study are discussed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.12-19
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• 1999

CERES-rice, a rice growth simulation model, was used in conjunction with daily weather data to figure out the spatial variation of the phenology and yields of paddy rice at 168 rice cultivation zone units(CZU) of Kyunggi Province in 1997. Two sets of cultivar specific coefficients, which represent early and mid-season maturing varieties, were derived from field experiments conducted at two crop experiment stations. The minimum data set to run the model for each CZU (daily maximum and minimum temperature, solar irradiance, and rainfall) was obtained by spatial averaging of existing 'Digital Map of Korean Climate'(Shin et al., 1999). Soil characteristics and management information at each CZU were available from the Rural Development Administration. According to a preliminary test using 5 to 9 years field data, trends of the phasic development(heading and physiological maturity), which were obtained from the model adjusted for these coefficients, were in good agreement with the observed data. However, the simulated inter-annual variation was somewhat greater than the reported variation. Rough rice yields of the early maturing cultivar calculated by the model were comparable with the reported data in terms of both absolute value and inter -annual variation. But those of the mid season cultivar showed overestimation. After running the simulation model runs with 1997 weather data for 168 CZU's, rough rice yields of the 168 CZU's calculated by the model were aggregated into corresponding 33 counties by acreage-weighting to facilitate direct comparison with the reported statistics from the Ministry of Agriculture and Forestry. The simulation results were good at 22 out of the 26 counties with reportedly increasing yield trend with respect to the past 9 years average.

• Journal of Korean Medical Science
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• v.33 no.52
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• pp.347.1-347.11
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• 2018

Background: Smartphone addiction has recently been highlighted as a major health issue among adolescents. In this study, we assessed the degree of agreement between adolescents' and parents' ratings of adolescents' smartphone addiction. Additionally, we evaluated the psychosocial factors associated with adolescents' and parents' ratings of adolescents' smartphone addiction. Methods: In total, 158 adolescents aged 12-19 years and their parents participated in this study. The adolescents completed the Smartphone Addiction Scale (SAS) and the Isolated Peer Relationship Inventory (IPRI). Their parents also completed the SAS (about their adolescents), SAS-Short Version (SAS-SV; about themselves), Generalized Anxiety Disorder-7 (GAD-7), and Patient Health Questionnaire-9 (PHQ-9). We used the paired t-test, McNemar test, and Pearson's correlation analyses. Results: Percentage of risk users was higher in parents' ratings of adolescents' smartphone addiction than ratings of adolescents themselves. There was disagreement between the SAS and SAS-parent report total scores and subscale scores on positive anticipation, withdrawal, and cyberspace-oriented relationship. SAS scores were positively associated with average minutes of weekday/holiday smartphone use and scores on the IPRI and father's GAD-7 and PHQ-9 scores. Additionally, SAS-parent report scores showed positive associations with average minutes of weekday/holiday smartphone use and each parent's SAS-SV, GAD-7, and PHQ-9 scores. Conclusion: The results suggest that clinicians need to consider both adolescents' and parents' reports when assessing adolescents' smartphone addiction, and be aware of the possibility of under- or overestimation. Our results cannot only be a reference in assessing adolescents' smartphone addiction, but also provide inspiration for future studies.

• Journal of the Korean Society of Tobacco Science
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• v.13 no.1
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• pp.19-26
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• 1991

Ames test using special strains which are histidine requiring mutant of Salmonella typhimufium , is widely utilized as short-term bioassay to evaluate the genotoxicity of chemicals. This method requires the liver microsome(5-9 fraction) to provide mammalian metabolism of the compounds, Therefore, the mutagenic potency of the chemicals is affected by not only the intrinsic properties of them but also the efficiency of the in vitro microsomal activation system. For this reason, the complex mixtures such as environmental pollutants from occupational sources, natural products or cigarette smoke condensates(CSC) , might be often appeared the false results. Induction of sister chromatid exchange(SCE) in cultured cells is known as another sensitive and powerful tool for the measurement of genotoxicity and the method has also an advantage which is able to apply to the in vitro and in vivo systems. In the present study, the inducibilities of revertant colonies in tester strain TA98 and SCE in human Iymphocytes by positive controls and total particulated materials(TPM) obtained from various brand(domastic and imported) cigarettes were compared in order to investigate whether the results in Ames test are in agreement with those in SCE analysis. The mutagenic activities of well known mutagens such as B(a)P showed excellent dose-response in the both methods although the induction mechanism was different each other, but cyclophosphamide resulted such effect only in SCE analysis. Most TPM tested showed a similar pattern in the mutagenic activities in those methods. However, only two(one imported brand and one domestic sample cigarettes) among the TMP obtained from various cigarettes appeared the higher induction in SCE than Ames test.

• Journal of Korean Neurosurgical Society
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• v.52 no.3
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• pp.204-209
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• 2012

Objective : The authors performed a retrospective study to assess the accuracy and clinical benefits of a navigation coupled with O-arm$^{(R)}$ system guided method in the thoracic and lumbar spines by comparing with a C-arm fluoroscopy-guided method. Methods : Under the navigation guidance, 106 pedicle screws inserted from T7 to S1 in 24 patients, and using the fluoroscopy guidance, 204 pedicle screws from T5 to S1 in 45 patients. The position of screws within the pedicle was classified into four groups, from grade 0 (no violation cortex) to 3 (more than 4 mm violation). The location of violated pedicle cortex was also assessed. Intra-operative parameters including time required for preparation of screwing procedure, times for screwing and the number of X-ray shot were assessed in each group. Results : Grade 0 was observed in 186 (91.2%) screws of the fluoroscopy-guided group, and 99 (93.4%) of the navigation-guided group. Mean time required for inserting a screw was 3.8 minutes in the fluoroscopy-guided group, and 4.5 minutes in the navigation-guided group. Mean time required for preparation of screw placement was 4 minutes in the fluoroscopy-guided group, and 19 minutes in the navigation-guided group. The fluoroscopy-guided group required mean 8.9 times of X-ray shot for each screw placement. Conclusion : The screw placement under the navigation-guidance coupled with O-arm$^{(R)}$ system appears to be more accurate and safer than that under the fluoroscopy guidance, although the preparation and screwing time for the navigation-guided surgery is longer than that for the fluoroscopy-guided surgery.

• Journal of agricultural medicine and community health
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• v.9 no.1
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• pp.39-45
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• 1984

This research was done to gain the health information in one of the target areas(rural area) of the Korea University Community Health Project, and to improve and standardize the methodology of the health interview survey. There were two types of questions;one was the simple open-ended question and the other was check list in the interview survey for a total of 1,406 inhabitants. And so the result obtained from the above survey was analysed. The results as follows; 1) The morbidity rate in general was 11.2% by simple open-ended question and 32.5% by check list during recent 20 days in interview method. 2) Women had higher morbidity rate in both kinds of method. 3) The most prevalent diseases in the interview method using check list were the ones of the musculo-skeletal system and connective tissue (22.5%), and diseases of the respiratory system (19.8%) and digestive system (13.7%) were in order of frequency. 4) By the position in the family, housewives had highest morbidity rate in the interview method unrespectedly, and the reason seemed that the respondents were houseweives themselves and the morbidity rate was the one by spell not by person. But morbidity rate by the socio-economic status had no significant difference in both methods. 5) The agreement rate on simple open-ended question and check list was 72.5%, but if limiting respondents themselves only, the rate was falled to 54%. 6) The morbidities were diverse in the review of the results of previous morbidity surveies, but the morbidity rate was higher and less variable in case of using check list and getting the replies individually than using simple open-ended question and proxy respondents.

• Journal of the Korean Chemical Society
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• v.19 no.3
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• pp.198-206
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• 1975

Polymers with photosensitive functional groups, the naphthoquinone-1,2-diazide-5-sulfonyl esters(PGND, BEND and PVAND) of polyglyceryl phthalate(PG), bisphenol A-epichlorohydrin polycondensate(BE) and polyvinyl alcohol(PVA), were prepared. The molecular weights of the starting materials were determined by the cryoscopic method, i.e., in the range of 650${\sim}$1200 for PG and 780${\sim}$1320 for BE, PGND, BEND and PVAND were prepared by esterification of PG, BE and PVA with naphthoquinone-1,2-diazidie-5-sulfonyl chloride, and the replacements of such a functional groups were confirmed by the infrared absorption spectra and elemental analyses. The good agreement between the observed values of elemental analyses (PGND, BEND and PVAND) and the calculated values, indicated that the degree of polymerization did not change in the course of esterification of PG, BE and PVA.