• Fire Science and Engineering
• /
• v.33 no.5
• /
• pp.13-18
• /
• 2019

In this study, the soot formation characteristics of Jet-A1 liquid fuel droplet flames were investigated by measuring the soot concentration under atmospheric conditions similar to the working environment of the Korea Space Launch Vehicle (KSLV) To obtain the desired atmospheric conditions, the oxygen concentration in the combustion chamber was maintained at 30% and the pressure was varied between 0.1 and 0.06 MPa. The full-field light extinction technique was used to measure the concentration of soot particles generated by applying the identical to 2-mm-diameter Jet-A1 fuel droplets. The soot concentration of the Jet-A1 droplet flames was the highest in the nitrogen-substituted atmosphere and the lowest in the carbon dioxide-substituted atmosphere, despite the pressure. the pressure was decreased the measured soot concentrations reduced as a function of Pⁿ.

• The Korean Journal of Pain
• /
• v.8 no.2
• /
• pp.298-303
• /
• 1995

We have inserted epidural catheter for single or continuous injection of a drug for epidural analgesia. It is important to localize the tip of epidural catheter in appropriate site to acquire the most effective analgesia. In epidural block, we observed course and location of the tip of epidural catheter. Subject: 70 patients were divided into group I(non-injection of saline group during catheter insertion) and group II(injection group during catheter insertion). Group I included cervical(n=20), thoracic(n=10), and lumbar(n=20) epidural group. Group II, cervical(n=10), and lumbar(n=10) epidural group. Method: 19G FlexTip $Plus^{TM}$ Epidural Catheter ($Arrow^{(R)}$) was inserted 10cm cephaladly in epidural space with(group II) or without(group I) saline flushing. We observed course and location of the tip of epidural catheter by C-arm image intensifier during injection of contrast media ($Omnipaque^{(R)}$). Result: In group I, the number of tips of epidural catheters located within 2 cm from inserted site were: cervical 14/20(70%), thoracic 2/10(20%). lumbar 16/20(80%). In thoracic epidural blocks, tips of epidural catheters were more cephaladly located than with cervical and lumbar epidural blocks. With cervical epidural blocks, the number of tips of epidural catheters located within 2 cm from insertion site were less in group II than group I (20% vs. 70%). But no significant differences were noted between group I and group II with lumbar epidural block(90% vs. 80%). The number of tips of epidural catheters located around a predicted site were: cervical 2/20(10%), thoracic 4/10(40%), lumbar 0/20(0%) in group I, and cervical 2/10(20%), lumbar 1/10(10%) in group II. Conclusion: It was impossible to predict the exact location of tips of epidural catheters by measuring the inserted length without epidurogram. With many cases, tips of epidural catheters were located around the insertion site in lumbar epidural blocks, and in some cases around the predicted site in thoracic epidural blocks. The results suggests that epidural block should be done at a point near the required band of analgesia.

• Journal of Digital Convergence
• /
• v.18 no.8
• /
• pp.1-9
• /
• 2020

This study aims to find new attributes by analyzing Korea and China duty free store online reviews and examine the influence of these attributes on star ratings(satisfaction)of duty free store. For study, we used Dazhong Dianping that largest online review site in China. Using R, we analyzed 5,659 reviews of Korea duty free store and 4,051 reviews of China duty free store. According to the analysis, Sale, Food and Membership attributes had a positive effect on star rating of Korea duty free store. Sale, Product, Airport, Food and Membership had a positive effect on star rating of China duty free store. This study has identified new factors such as food that showed the importance of providing space of restaurants while shopping at duty free store. This study has contributed to the existing literature by finding new attribute such as food. Practically, this finding will help to duty free industry workers better understand the impact of providing space of restaurants on duty free store.

• Korean Journal of Mineralogy and Petrology
• /
• v.33 no.3
• /
• pp.251-258
• /
• 2020

Single crystal of fully dehydrated and partially Ca²⁺-exchanged zeolites A (|Ca₄Na₄|[Si₁₂Al₁₂O₄₈]-LTA) was brought into contact with Se in fine pyrex capillary at 523 K for 5 days. Crystal structure of Se-sorbed |Ca₄Na₄|[Si₁₂Al₁₂O₄₈]-LTA has been determined by single-crystal X-ray diffraction techniques at 294 K in the cubic space group $Pm{\bar{3}}m$ (a = 12.2787(13) Å). The crystal structure of yellow |Ca₄Na₄Se₄|[Si₁₂Al₁₂O₄₈]-LTA has been refined to the final error indices of R₁/wR₂ = 0.0960/0.3483 with 327 reflections for which F_o > 4s(F_o). In this structure, 4 Na⁺ and 4 Ca²⁺ ions fill every 6-ring site: These ions are all found at three crystallographic positions, on 3-fold axes equipoints of opposite 6-rings. Selenium atoms are found at three crystallographically distinct positions: 2 Se atoms per unit cell at Se(1) are located opposite 6-rings in the sodalite cavity (Se(1)-Na(1) = 2.53(5) Å) and 1 at Se(2) opposite 4-rings (Se(2)-O(1) = 2.76(10) Å) and 1 at Se(3) opposite 6-rings in the large cavity (Se(3)-Na(1) = 2.48(5) Å). Two molecular of Se₂ (Se(1)-Se(1) = 2.37(7) or 2.90(8) Å and Se(2)-Se(3) = 2.91(5) ) Å) are found in all sodalite cavity and large cavity. Other clusters such as Se₄ and Se₈ could be existed in large cavity. The inter-selenium distances turned out to be longer that of gases Se₂ molecule.

• Journal of Korean Society of Water and Wastewater
• /
• v.32 no.3
• /
• pp.221-233
• /
• 2018

Two climate change scenarios, the RCP (Representative Concentration Pathways) 4.5 and the RCP 8.5 in the fifth Assessment Report (AR5) by Intergovernmental Panel on Climate Change (IPCC), were applied in the Yocheon basin area using the SWAT (Soil and Water Assessment Tool) model to estimate changes in flow rates and pollutant loadings in the future. Field stream flow rate data in Songdong station and water quality data in Yocheon-1 station between 2013~2015 were used for model calibration. While $R^2$ value of flow rate calibration was 0.85 and $R^2$ value of water qualities were in the 0.12~0.43 range. The total study period was divided into 4 sub periods as 2030s (2016~2040), 2050s (2041~2070) and 2080s (2071~2100). The predicted results of flow rates and water quality concentrations were compared with results in calibrated periods, 2015s (2013~2015). In both RCP scenarios, flow rate and TSS (Total Suspended Solid) loadings were estimated to be in increasing trend while TN (Total Nitrogen) and TP (Total Phosphorus) loadings showed decreasing patterns. Also, flow rates and pollutant loadings showed larger differences between the maximum and the minimum values in RCP 4.5 than RCP 8.5 scenarios indicating more severe effect of drought and flood, respectively. Dependent on simulation period and rainfall periods in a year, flow rate, TSS, TN and TP showed different trends in each scenario. This emphasizes importance of considerations on time and space when analyzing climate change impacts of each variable under various scenarios.

• Asian Journal of Turfgrass Science
• /
• v.25 no.1
• /
• pp.69-72
• /
• 2011

Soil aggregate is a vigorous procedure including soil physical, chemical, and biological processes. Pore space created by binding these particles together improves retention and exchange of air and water. Various researches have reported that the benefits of organic polymers that may increase aggregate stability. The purpose of the study was to determine if a liquid organic polymer mixture has any influence on perennial ryegrass quality or soil aggregation. $Turf2Max^{(R)}$ was applied to two soils as a source of liquid organic polymer. Fine-loamy soil from local Iowa topsoil with 4.0% organic matter was screened and dried. Commercial baseball infield clay, $QuickDry^{(R)}$, was used as the second soil There were three rates of liquid organic polymer (0, 2, and 4%). there was no visual improvement in turf grass color, quality, or growth by using organic polymer. It is possible that aggregate stability increases with use of organic polymer. The aggregate stability study needs to be repeated in the greenhouse and then substantiated under field conditions for these preliminary observations.

• Journal of the Korean Society of Costume
• /
• v.65 no.8
• /
• pp.110-124
• /
• 2015

This study examined a phenomenon of exaggerated hairstyle in the history of Western custom through publications related with Western costume and research papers. By adopting the criteria of Delong, M. R. to analyze visual forms shown by interaction between human body and costume worn over the body, it analyzed the formative characteristics by the interaction between hairstyle and costume. In addition, it inferred the aesthetic characteristics through content analysis of examined phenomenon focusing on socio-cultural background and costume socio-psychological precedent studies. Formative characteristics of exaggerated hairstyle applied by analysis criteria of Delong, M. R. were in pursuit of the emphasis style. This was clearly and intensively recognized by forming spaces for mostly closure style, part style, three dimensional style, determinate style, and space separation style. Regarding the interaction between hair and ornamentations, 'precedence of ornamentation' was pursued as ornamentations were recognized earlier than the hair itself. It means associative meanings of the surface effect were accompanied by emotions of 'intensiveness' and the pursuit of the attractive style. As for the interaction between hairstyle and costume, there were many cases of pursuing 'continuity' mutually and visually by connecting the hairstyle and the costume. Aesthetic characteristics of exaggerated hairstyle were inferred as 1) the expression of the sprite of the age(i.e. art, culture, politics, society, ideology, religion), 2) symbols of wealth, class, authority, and excellence, 3) pursuit of addicted desire to ornament, and 4) harmony through continuity with costume. This study verified that hairstyle was connected as a part of costume, or formed as a way to express deeper human psychology beyond just a part of a costume. It was also confirmed that hairstyle was an expressive method to express the spirit of the age, such as art, culture, society, religion, ideology.

• Bulletin of the Korean Mathematical Society
• /
• v.31 no.2
• /
• pp.187-192
• /
• 1994

The author extended the small properties of topological semilattices to that of regular semigroups [3]. In this paper, it could be shown that a semigroup S is almost regular if and only if over bar RL = over bar R.cap.L for every right ideal R and every left ideal L of S. Moreover, it has shown that the Bohr compactification of an almost regular semigroup is regular. Throughout, a semigroup will mean a topological semigroup which is a Hausdorff space together with a continuous associative multiplication. For a semigroup S, we denote E(S) by the set of all idempotents of S. An element x of a semigroup S is called regular if and only if x .mem. xSx. A semigroup S is termed regular if every element of S is regular. If x .mem. S is regular, then there exists an element y .mem S such that x xyx and y = yxy (y is called an inverse of x) If y is an inverse of x, then xy and yx are both idempotents but are not always equal. A semigroup S is termed recurrent( or almost pointwise periodic) at x .mem. S if and only if for any open set U about x, there is an integer p > 1 such that x$^{p}$ .mem.U.S is said to be recurrent (or almost periodic) if and only if S is recurrent at every x .mem. S. It is known that if x .mem. S is recurrent and .GAMMA.(x)=over bar {x,x$^{2}$,..,} is compact, then .GAMMA.(x) is a subgroup of S and hence x is a regular element of S.

• Archives of design research
• /
• v.14
• /
• pp.321-333
• /
• 1996

The typeface of the Shhnch 'ongjon woodblocks is unsophisticated and old-fashioned while at the same time having a tidiness and strength that give it its special appeal. This is the typeface used in publishing novPls for sale to the common people during the latter half of the Choson Dynasty_ Their demands could not be satisfied with most currently available literature. which was intended to suit the tastes of the official class. As a result of a development to overcome the unbalanced use of space characteristic of letterforms that followed the geometric principles of early Hangul. the typeface followed the refined. feminine "hrushstroke" style of kungch 'e. establishing itself as a "rough" face displaying the characteristics of carved. woodblock printing in answer to the needs of the common p-eople who had the greatest need of Hangul during the time of its f1owering. The Shhnch 'ongjon face is characterized by thin horizontal strokes. thick vertical strokes. and the appearance of being condensed left to right. They possess simple yet varied form. With these characteristics the Shimch' ongjon typeface. if revived and compared to other typefaces. has a beauty of structure and composition and a unique. modern lmage with excellent readability. giving it great significance for modern r langul typography.r langul typography.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.17 no.1
• /
• pp.154-161
• /
• 2009

This study is a part of project of urea-SCR system development for an in-use medium duty diesel engine. This study shows the effect of ammonia oxidation catalyst and SCR volume on $NO_X$ reduction performance. When AOC(Ammonia Oxidation Catalyst) is not used, the urea injection should be controlled accurately to prevent $NH_3$ slip. However, it is found that the accurate $NH_3$ slip control is not easy without AOC in real engine operating conditions, because $NH_3$ and $NO_X$ reaction characteristics change with many factors such as exhaust gas temperature and $NH_3$ absorbance on SCR. SCR volume is also one of important design parameters. This study shows that $NO_X$ reduction efficiency increases with increase of SCR volume especially at high space velocity and low exhaust gas temperature conditions. Additionally, this paper shows the emissions of EURO-2 medium duty diesel engine can be improved to the level of EURO-5 with a DPF and urea-SCR system.