• Bulletin of the Korean Chemical Society
• /
• 제18권6호
• /
• pp.573-578
• /
• 1997

Ion fragmentations of fatty acids such as stearic acid, palmitic acid, myristic acid, and lauric acid were studied using mass spectrometry and semiempirical calculations. The mass spectra of fatty acids showed the distributions of CH₃(CH₂)$_n^+$ and $[(CH_2)_nCO_2H]^+$ fragment ions. The relative ion abundance distributions of $[(CH_2)_nCO_2H]^+$ showed the local maxima at n=6, 10, and 14. The local maximum phenomena were also found in the mass spectra of methyl stearate but not in those of normal alcohols. These local maxima could be explained not by heats of reaction for fragmentation but by the cyclic structures of the molecular ions. The AM1 semiempirical calculations for fatty acids clearly show that the linear structures are more favorable than the cyclic ones for neutral molecules while the cyclic structures are more favorable than the linear ones for ionic molecules. The distances between carboxyl group and methylene of the cylic structures of ionized fatty acids were calculated. The methylene carbons with n=6, 10, and 14 were closer to the carboxyl group than adjacent ones.

• 대한기계학회논문집B
• /
• 제21권1호
• /
• pp.125-131
• /
• 1997

The extinction of premixed flames under the influence of stretch is studied numerically. A wide range of fuel (hydrogen, ethylene, acetylene, methane, propane and methanol) and air mixtures are established in an opposed jet and their flame properties such as flame speed, flame thickness, thermal diffusivity, and stretch rate at extinction are computed. Computations are made using several chemical kinetic mechanism (Smooke, Kee et al. and Peters). The major result is that, in contrast to the various previous claims of extinction Karlovitz number varying over three orders of magnitude, it is found to be constant around two for all of the mixtures tested. That is, premixed flames are extinguished when the physical flow time decreases (due to increased stretch rate) to the point where it approximately equals the chemical reaction time. Here the relevant chemical reaction time is not the one computed using the one-dimensional flame properties as originally suggested in the formulation of Karlovitz number, but rather it is the one obtained using the stretched flame properties which fully reflect the effect of straining on the flame structure.

• 한국항공우주학회지
• /
• 제47권5호
• /
• pp.371-378
• /
• 2019

정밀지향위성은 반작용휠로 자세제어를 수행하며, 반작용휠의 모멘텀 덤핑은 3개의 자기토커로 이뤄진다. 본 논문에서는 자기토커 고장 시의 모멘텀 덤핑 영향성에 대해서 살펴본다. 높은 경사각을 가지는 궤도에 위치한 위성이 지구지향자세를 유지하고 있을 때 피치축 방향 자기토커가 고장나면 모멘텀 덤핑이 불가능하다. 하지만 다른 방향의 자기토커가 고장나면 성능 저하만 있을 뿐 모멘텀 덤핑은 여전히 가능하다. 피치축 방향의 자기토커가 고장났을 때도 위성자세변화를 통해서 모멘텀 덤핑을 할 수 있다. 또한 자기토커 배치를 변경하면, 어느 자기토커가 고장나더라도 모멘텀 덤핑이 항상 가능하다.

• 복식문화연구
• /
• 제12권2호
• /
• pp.279-289
• /
• 2004

This study was conducted to compare the hunting reaction of finger in the cold water. Finger skin temperature is measured the left middle finger tip immersion in cold water of 5℃ for 30 minutes and measurements were made on finger skin temperature(Ts), thermal comfort, and cold pain sensations during the experiment at the spring (March) and Winter(December). Results were follows. Is before immersion was at the highest in spring and at the lowest in winter and was closely related to the indoor temperature Ts during immersion and recovery. Mean of finger skin temperature(MST), the skin temperature at the first rise(TTR) and amplitude of finger skin temperature reaction during immersion(AT) were significant higher in spring than that in winter(P＜.01). The lowest skin temperature(LST) during the cold water immersion were significantly higher in spring than that in winter (P＜.05). The frequency of the appearance of cold-Induced vase dilation(CIVD) was higher in spring than that in winter. However, time for the first temperature(TTR) and recovery time(RT) had no seasonal variation. In addition, cold pains during immersion were felt more strongly in spring than in winter. Local thermal sensation, finger thermal sensation in dynamic state during hand immersion was different from that in the Winter. Spring was slowly cold in cold water immersion.

• 한국전산유체공학회지
• /
• 제21권1호
• /
• pp.43-49
• /
• 2016

Thermal cracking is commonly modeled as plug flow reaction, neglecting the lateral gradients present. In this paper, 2-dimensional computational fluid dynamics including turbulence model and molecular reaction scheme are carried out. This simulation is solved by means of coupled implicit scheme for stable convergence of solution. The reactor is modeled as an isothermal tube, whose length is 1.2 m and radius is 0.01 m, respectively. At first, The radial profile of velocity and temperature at each point are predicted in its condition. Then the bulk temperature and conversion curve along the axial direction are compared with other published data to identify the reason why discussed variations of properties are important to product yield. Finally, defining a new non-dimensional number, Effect of interaction with turbulence, heat transfer and chemical reaction are discussed for design of thermal cracking furnace.

• Natural Product Sciences
• /
• 제16권3호
• /
• pp.185-191
• /
• 2010

Mast cell-mediated allergic disease is involved in many diseases such as anaphylaxis, asthma and atopic dermatitis. The discovery of drugs for the treatment of allergic disease is an important subject in human health. In the present study, the effect of water extract of Gleditsiae Spina (WGS) (Leguminosae), on compound 48/80-induced systemic allergic reaction, anti-DNP IgE antibody-induced local allergic reaction, and histamine release from human mast cell line (HMC-1) cells were studied. In addition, the effect of WGS on phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187 (A23187)-induced gene expression and secretion of pro-inflammatory cytokines were investigated using HMC-1 cells. WGS was anally administered to mice for high and fast absorption. WGS inhibited compound 48/80-induced systemic allergic reaction. WGS dose-dependently decreased the IgE-mediated passive cutaneous anaphylaxis. WGS reduced histamine release from HMC-1 cells. In addition, WGS decreased the gene expression and secretion of pro-inflammatory cytokines in PMA plus A23187-stimulated HMC-1 cells. These findings provide evidence that WGS could be a candidate as an antiallergic agent.

• Child Health Nursing Research
• /
• 제22권1호
• /
• pp.21-28
• /
• 2016

Purpose: The purpose of this study was to identify effects of EMLA (Eutectic Mixture of Local Anesthetics) cream application on pain perception and pain response during insertion of implanted venous access port needle in children with cancer. Methods: From December 2010 to August 2011, at U university hospital, 20 patients scheduled for implanted venous access port needle insertion were recruited, and randomly assigned to receive either EMLA or a placebo cream 1 hour before the implanted venous access port needle insertion. While conducting needle insertion, changes in pulse and oxygen saturation on the pulse oxymeter monitor were measured and pain behavior reaction was also measured during needle insertion in the treatment room. After conducting needle insertion, self-reported pain reaction, and mothers' perception of the children's pain reaction were measured. Collected data were statistically processed using SPSS version 17.0 for Windows, and analyzed using descriptive statistics, t-test. Results: Children's self-reported degree of pain, degree of pain as perceived by mothers and pain behavior reaction decreased significantly in the EMLA application group compared with the placebo group. Conclusion: Findings indicate that application of EMLA cream is effective in relieving pain in these children during implanted venous access port needle insertion.

• Toxicological Research
• /
• 제16권1호
• /
• pp.17-25
• /
• 2000

Chitosan cross-linked collagen-glycosaminoglyan (CCGM) is an artificial skin substitute made to form a sponge like dimensional matrix. It can be used to facilitate reconstruction of dermal tissue when applied on large wounds such as severe burns. In order to study the toxicological effects of CCGM the cytotoxicity, local irritation and skin sensitization test were carried out according to the standards of ISO 10993. In the cytotoxicity test utilizing LDH and MTT test, both the CCGM and its extract had no toxicity of Balb/c 3T3 cells. The local irritatioin test on rabbit skin demonstrated that CCGM did not promote any harmful when directly applied on skin. In addition, it did not elicit any allergic reaction in the guinea pig maximization test. Based on these results, it is suggested that CCGM is a material without cytotoxicity, local irritation and allergenicity.

• 대한기계학회논문집A
• /
• 제28권11호
• /
• pp.1813-1821
• /
• 2004

Until now, the 40% of wall thickness criterion, which is generally used for the plugging of steam generator tubes, has been applied only to a single cracked geometry. In the previous study by the authors, a total number of 9 local failure prediction models were introduced to estimate the coalescence load of two collinear through-wall cracks and, then, the reaction force model and plastic zone contact model were selected as the optimum ones. The objective of this study is to estimate the coalescence load of two collinear through-wall cracks in steam generator tube by using the optimum local failure prediction models. In order to investigate the applicability of the optimum local failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two collinear through-wall cracks in steam generator tube were carried out. Thereby, the applicability of the optimum local failure prediction models was verified and, finally, a coalescence evaluation diagram which can be used to determine whether the adjacent cracks detected by NDE coalesce or not has been developed.

• 한국양식학회지
• /
• 제10권4호
• /
• pp.403-407
• /
• 1997

Intraspecific sequence variation was detected by polymerase chain reaction (PCR) and direct sequencing of a 350-nucleotide region of the mitochondrial 12S rRNA gene of two natural populations (Han River and Nakdong River) and one hatchery stock (Jinhae Inland Fisheries Institute) of local strain common carp, one Israeli strain of common carp stock from Pukyong National University (PKU), and one hybrid between Israeli strain of common carp female and local strain common carp male from PKU stock. There is little variation in 350 bases of the mitochondrial 12S rRNA gene sequences among 2 natural and 1 hatchery local strain common carp populatins, representing abut 7 to 20 nucleotide differences (less than 6%). The sequence of specimens from Han River was more similar to that from Nakdong River (identity=98.0%) than to that from Jinhae Inland Fisheries Institute (identity=96.3%). Sequence variation between Israeli strain and wild local strain common carp was higher than the variation within natural stocks. The level of variation was ranged from 15.7 to 17.7%. The hybrid showed very similar nucleotide4 sequence of 12S rRNA gene to the sequence of Israeli strain with the identity of 98.9%.