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Effect of Chemical Interaction on Flame Extinction in Interacting H2-air and CO-air Premixed Flames (H2-공기와 CO-공기의 예혼합화염의 화염소화에 있어서 화학적 상호작용의 효과)

  • Jung, Seongwook;Park, Jeong;Kwon, Ohboong;Keel, Sangin;Yun, Jinhan
    • Journal of the Korean Society of Combustion
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    • v.18 no.4
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    • pp.44-52
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    • 2013
  • Important role of chemical interaction in flame extinction was numerically investigated in downstream interaction among lean(rich) and lean(rich) premixed as well as partially premixed $H_2$-air and CO-air flames. The strain rate varied from 30 to $5917s^{-1}$ until interacting flame could not be sustained anymore. Flame stability diagrams mapping lower and upper limit fuel concentrations for flame extinction as a function of strain rate are presented. Highly stretched interacting flames were survived only within two islands in the flame stability map where partially premixed mixture consisted of rich $H_2$-air flame, extremely lean CO-air flame, and a diffusion flame. Further increase in strain rate finally converges to two points. Appreciable amount of hydrogen in the side of lean $H_2$-air flame also oxidized the CO penetrated from CO-air flame, and this reduced flame speed of the $H_2$-air flame, leading to flame extinction. At extremely high strain rates, interacting flames were survived only by a partially premixed flame such that it consisted of a very rich $H_2$-air flame, an extremely lean CO-air flame, and a diffusion flame. In such a situation, both the weaker $H_2$-air and CO-air flames were parasite on the stronger diffusion flame such that it could lead to flame extinction in the situation of weakening the stronger diffusion flame. Particular concerns are focused on important role of chemical interaction in flame extinction was also discussed in detail.

Dynamic Analysis of Tracked Vehicle by Buoy Characteristics (부이 특성에 따른 궤도 차량 동적 거동)

  • Kim, Hyung-Woo;Min, Cheon-Hong;Lee, Chang-Ho;Hong, Sup;Bae, Dae-Sung;Oh, Jae-Won
    • Ocean and Polar Research
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    • v.36 no.4
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    • pp.495-503
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    • 2014
  • This paper focuses on the dynamic responses of a tracked vehicle crawling on extremely cohesive soft soil, each side of which is composed of two parallel tracks. The tracked vehicle consisted of 2 bodies. One body is the tracked vehicle body, which is assumed to be a rigid body with 6 DOFs. The other body is the buoy body. The two bodies are connected by a revolute joint. In order to evaluate the travelling performance of a 7 DOFs vehicle, a dynamic analysis program for the tracked vehicle was developed using Newmark's method and the incremental-iterative method. The effects of road wheels on the track and soil are not taken into account. A terra-mechanics model of extremely cohesive soft soil is implemented in form of relationships: normal pressure to sinkage, shear resistance to shear displacement, and dynamic sinkage to shear displacement. Pressure-sinkage relationship and shear displacement-stress relationship should represent the non-linear characteristics of extremely soft soil. Especially, since the shear resistance of soft soil is very sensitive to shear displacement, spatial distribution of shear displacement occurring at the contact area of the tracks should be calculated precisely. The proposed program is developed in FORTRAN.

Geographic Variation in Survival Rate and Height Growth of Pinus densiflora S. et Z. in Korea

  • Kim, In-Sik;Ryu, Keun-Ok;Song, Jeong-Ho;Kim, Tae-Su
    • Journal of Korean Society of Forest Science
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    • v.94 no.2 s.159
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    • pp.73-81
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    • 2005
  • This study was conducted to examine the geographic variation among provenances of Pinus densiflora in survival rate and height growth at four test plantations (Jungsun, Chungju, Naju, and Jeju). The plantations were parts of the eleven provenance trials of Pinus densiflora established by Korea Forest Research Institute in 1996. The survival rate and height growth were significantly different among test plantations at $p{\leq}0.01$. Latitude and longitude of test plantation were negatively correlated with survival rate and height growth. On the other hand, annual mean temperature, mean temperature (Nov.~Feb.), extremely low temperature (Dec.~Feb.), and annual mean growing days of test plantation were positively correlated with these two. The relationships between growth variables and geographic variables were analysed with canonical correlation analysis. A considerable amount of variation in survival rate and height growth was explained by latitude, annual mean growing days, extremely low temperature (Dec.~Feb.) and extremely high temperature (Nov.~Feb.) of provenances. It is estimated that up to 47.1% and 67.4% of the genetic variability in survival rate and height growth was attributable to the environmental variability of the provenances, respectively. The response surface curve of survival rate and height growth was plotted against latitude and longitude to examine growth performance of provenances for each test site. Generally, the local provenances showed better survival rate and height growth.

Outcomes of Extremely Low Birth Weight Infants at the Asan Medical Center between 2003 and 2006 (단일 기관에서의 초극소 저출생 체중아의 치료 성적(2003-2006))

  • Park, Mee-Rim;Lee, Byong-Sop;Kim, Ellen A.;Kim, Ki-Soo;Pi, Soo-Young
    • Neonatal Medicine
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    • v.15 no.2
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    • pp.123-133
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    • 2008
  • Purpose: The purpose of this study was to determine the outcomes of extremely low birth weight infants (ELBWI) who were born at the Asan Medical Center and evaluate the recent status of neonatal intensive care and associated problems. Methods:We retrospectively evaluated 120 inborn ELBWI who were admitted to the NICU of the Asan Medical Center between 2003 and 2006. The survival rate, neurodevelopmental outcomes, maternal and infant factors, and infant mordibities were evaluated and the relationships with survival and catch-up growth were investigated. Results:The survival rate of the ELBWI was 82% at a mean gestational age of 27+2 weeks, and with a mean birth weight of 801.3${\pm}$129.0 g. The duration of hospitalization was 85.7${\pm}$27.2 days, the duration of O2 use was 43.9${\pm}$35.4 days, and the duration of ventilatory support was 20.9${\pm}$20.9 days among the survivors. The incidence of respiratory distress syndrome, chronic lung disease, severe intraventricular hemorrhage, and periventricular leukomalacia were 41.8%, 61.2%, 3%, and 4%, respectively. The mean mental developmental index and psychomotor development index of Bailey Scales of Infant Development (II) at follow-up were 83.4${\pm}$18.2 and 83.3${\pm}$20.3, respectively. Among the infants who had >18 months of follow-up, 50.8% had catch-up growth at 12 months. Conclusion:The survival rate of ELBWI has improved; however, the morbidities remain high, thus indicating further efforts must be implemented to reduce morbidity and improve neurodevelopmental outcomes.

Development of evidence-based protocol to maintain high humidity of incubator in Extremely Low Birth Weight Infant (초극소 저출생체중아의 고농도 가습환경 유지를 위한 근거중심 프로토콜 개발)

  • Yu, Mi;Choi, Yun-Jin;Han, Li-La;Yun, Young-Mi;Bae, Geun-Ha;Lee, Ji-Eun;Park, Ji-Seon;Park, Ui
    • Journal of Korean Critical Care Nursing
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    • v.2 no.2
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    • pp.5-17
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    • 2009
  • Purpose: The purpose of this study was to investigate the current humidification state of incubator, the factors disturbing high humidification and to establish the evidence-based nursing protocol to maintain it. Methods: The subjects were 15 infants who were born with extremely low birth weight (ELBW) from May to October, 2007, and data were collected during the first 3 days and analyzed with SPSS WIN program. Results: The goal of humidity level in incubator was 95%, but mean humidity levels were 89.7%(1st day), 91.9%(2nd day), and 91.8%(3rd day)(p<0.001). The disturbing factors were opening frequency and duration of incubator door and window by caregivers. The handling of infants by nurses and doctors happened more frequently during the first day. Especially, nurses handled them more often than others, but the duration of opening during the invasive procedures by doctors was longer than others. The opening frequency had negative correlation with duration(r=-.779, p<.01). Conclusion: So the evidence-based protocol for maintaining high humidity in incubator for ELBW infants during the first 3 days and next 2 days was made. Furthermore we need to educate NICU nurses and doctors about minimal handling.

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A Study on the Factors for Improvement of Chemical and Physical Properties in Fluoric Rubber Coating for Use of the Extremely Acidic Environments

  • Chang, Hyun Young;Jin, Tae Eun;So, Il Soo;Lee, Byung Seung;Kang, Min Soo
    • Corrosion Science and Technology
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    • v.7 no.5
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    • pp.269-273
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    • 2008
  • It is known that the fluoric resin has the most outstanding properties in the extremely acidic environment of high temperature. However, this resin is the thermal hardening type that needs long time heat treatments above $250^{\circ}C$. It's impossible to use in situ in the extremely acidic environment such as a huge FGD ductworks or industrial chemical tanks. Furthermore, even the natural hardening type fluoric coatings which can be hardened less than $120^{\circ}C$ can not be applied to the highly acidic environmental plants because of its chemical resistance. In this study, new fluoric coatings that has excellent thermal resistance, chemical resistance and corrosion resistance has been developed in order to solve above problems and to be applied to the large plant structures in the field. These newly developed coatings are organic and inorganic composite type that have fluoric rubber(100 wt%), fluoric resin(5~50 wt%), oxalates(5~30 wt%), inorganic fillers mixed with plate-type and bulk-type solids(20~150 wt%), hardeners(0.5~5 wt%), and hardening hasteners(0.1~3 wt%). The best chemical and physical properties of these coatings are acquired by variation of adhesive reinforcement agents, dispersants, leveling agents. Mixing ratios of plate-type and bulk-type inorganic fillers influence the thermal properties, abrasive resistance and chemical infiltration properties of coatings. The mixing control is also very important to have homogeneous surface and removing inner voids of coatings.

Relationship Between Urinary Melatonin Levels and Extremely Low Frequency Magnetic Fields for the Selected Primary Schoolchildren Living Nearby and Away from Overhead Transmission Power Line (송전선로 주변과 비주변 초등학생을 대상으로 극저주파 자기장 노출과 뇨중 멜라토닌 분비량간의 상관성 연구)

  • Cho, Yong-Sung;Kim, Yoon-Shin;Lee, Jong-Tae;Hong, Seung-Cheol;Jang, Seong-Ki
    • Journal of Environmental Health Sciences
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    • v.30 no.3
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    • pp.191-206
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    • 2004
  • The present study investigated the hypothesis that a extremely low frequency magnetic field partially suppresses the synthesis of melatonin in a group of 28 primary schoolchildren living nearby and 60 primary schoolchildren aged 12 years living far away from overhead transmission power lines from December 2003 to April 2004 in Seoul, Korea. The mean personal exposure levels of the primary schoolchildren living nearby overhead transmission power line were 0.37 ${\mu}$T, whereas the value for the primary schoolchildren living away from overhead transmission power line 0.05 mT. From simple analyses, the mean melatonin levels in the primary schoolchildren living nearby were lower than away from overhead transmission power line, but not statistically significant differences in the levels of the melatonin (p=0.2421), whereas the statistically significant differences in the levels of the melatonin related to the distance from residence to power line less and more than 100 m by cut-off point (p=0.0139). In multiple linear regression analyses, distance from residence to power line (p=0.0146) and dietary habit about burned meat (p=0.0170) proved to be significant risk factors in the mean nocturnal melatonin levels in the primary schoolchildren. In conclusion, these results demonstrate that urinary levels of nocturnal melatonin are not altered in primary schoolchildren exposed to extremely low frequency magnetic field(ELF-MF) at overhead transmission power line.

Nursing Experience of Caring for Extremely Low Birth Weight Infants (초극소미숙아 돌봄을 통한 간호경험)

  • Kim, Hack-Sun;Choi, Kyung-Sook;Kim, Jung-Sook;Lee, Joo-Hyun
    • The Journal of Korean Academic Society of Nursing Education
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    • v.17 no.2
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    • pp.257-266
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    • 2011
  • Purpose: The aim of this study was to elucidate the themes involved in a nursing experience of caring for extremely low birth weight infants (ELBWIs) in a neonatal intensive care unit (NICU). Methods: Interviews with 6 nurses in various positions and observations in a level III NICU were conducted. The transcribed interview contents and observational notes were reviewed to analyze the data and conceptualize major themes. Results: Three major themes were identified: the fears expressed by the nurses regarding taking care of ELBWIs, reasons for persistent fears, and overcoming fears and gaining intuition. Nurses were afraid of the following factors: the physical fragility of the infants; the possibility of developing disabilities in the future; and the rapid changes in infants' physical condition. These fears were reduced when nurses had developed intuition and confidence in taking care of ELBWIs through various situational experiences. Conclusion: NICU nurses may benefit from obtaining more opportunities to participate in various learning experiences with simulated nursing situations in a variety of patient groups. Applying knowledge and skills into various nursing situations in an integrative way may contribute to enhancing nurses' confidence in nursing practice.

Health Status Evaluation Based on Questionnaire SF-36 Among Residents Exposed and Non-exposed to Extremely Low Frequency-electric and Magnetic Fields (ELF-EMFs) (설문조사에 근거한 전자파 발생원 주변 주민과 비주변 주민의 건강수준 평가)

  • Jeon, Hyung Jin;Kim, Yoon Shin;Yoon, Jeong Ho;Cho, Nam Wook;Son, Seoung Woo
    • Journal of Environmental Health Sciences
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    • v.40 no.5
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    • pp.376-384
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    • 2014
  • Objective: The purpose of this study is to compare the health status of residents who were exposed to sources of extremely low frequency electromagnetic fields (ELF-EMFs) in the living environment and those who were not exposed to such a source of ELF-EMFs through a survey designed to appraise the residents' health levels. Method: Aimed at 251 residents exposed to a source of ELF-EMFs and 278 residents not exposed to a source, the survey was conducted to investigate the health status of the residents on the basis of questionnaire SF-36. Result: The health status scores of residents exposed to ELF-EMFs turned out to be lower than those of their counterparts. In terms of self-reported symptoms related to health and sleep quality, residents exposed to ELF-EMFs were found to have a higher complaint rate of self-reported symptoms such as dizziness, depression, and fatigue. Regarding sleep disorders, residents exposed to ELF-EMFs appeared to have a slightly higher complaint rate of sleep disorders compared to non-exposed residents. Conclusion: If a region is to be exposed to a source of ELF-EMFs, a more proactive policy for reducing such exposure is advised. In addition, it is necessary to better understand problems of residents by emplacing an ELF-EMFs risk information delivery system and building an efficient communication system for voluntary participation during the construction phase.

The Research of the Brand Image of Extremely Low-end Cosmetics (초저가화장품의 브랜드 이미지에 관한 연구)

  • Choi Keum-ju;Kim Ju-duck
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.31 no.2 s.51
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    • pp.179-187
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    • 2005
  • The reduced production of domestic cosmetics in 2003, compared to last 5 years shows the recession of cosmetics industry. Under this situation, there has been reorganization on the domestic cosmetic market that low-end cosmetic .products become a trend due to the fact that major cosmetic companies also focus on low-end market since the last half year of 2004. However, it does not seem to be a temporal fashion that the extremely low-end cosmetics had an impact wavelength on cosmetics market. It has important meaning for the brand product strategy. This research focused on analysis of market situation and strategy through investigation of requirement and satisfaction on extremely low-end cosmetics in order to keep and improve it, which stimulated depressed cosmetic market.