• Elastomers and Composites
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• 제44권3호
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• pp.282-289
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• 2009

The pressure-sensitive adhesive(PSA) tapes are widely used as floor-sealing material in Korean constructive industry. However, the general PSA tapes can not seal the apertures completely. This is one of main reasons to cause imperfect finishing. In order to solve the problems, the asphalts were modified by FKM powder and SBS in this study. The physical properties of modified asphalts were examined by measuring the softening point, viscosity, tensile strength and adhesion strength of FKM and SBS modified asphalt. The softening point of SBS modified asphalt was increased greatly due to the formation of network structure in asphalt. Also, the change of adhesion strength of SBS modified asphalt with temperature was not so great comparing to those of pure asphalt and FKM modified asphalt. The best results of pressure-sensitive adhesion could be obtained by the SBS(linear) modified asphalt containing 6 wt.% of linear type SBS.

• Proceedings of the KOR-BRONCHOESO Conference
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• 대한기관식도과학회 1996년도 대한이비인후과학회 종합학술대회 초록집
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• pp.81-81
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• 1996

선천성 후두열은 매우 드문 선천성 기형으로 신생아에게 심각한 호흡곤란 및 수유장애를 초래할 수 있다. 해부학적 결손정도와 관련된 기형에 따라 다양한 증상이 나타난다. 가장 흔한 특징적 증상으로는 흡기시 천명, 간헐적으로 나타나는 수유시 호홉곤란을 들 수 있다. 이 증상들은 후두연화증, 성대마비, 후비공폐색 둥과 같은 다른 선천성 기형에서도 나타나기 때문에 미리 의심하지 못하면 진단이 어렵다. 따라서 진단을 위해서는 세심한 주의와 정확한 내시경 검사가 필요하다. 저자들은 선천성 후두열 2례를 경험하였다. 첫 증례는 제 II형이었고 두번째는 III형이었으며, 두 증례 모두 전방 후두열 접근법으로 치료하였다. 제 III형 환아는 술전 흡기시 천명을 동반한 호흡곤란과 여러번의 흡인성 폐렴을 겪었으며 술후 캐놀라발거는 가능하였으나 경구를 통한 수유시 흡인을 동반하여 현재까지 위루술을 통해 음식을 섭취하고 있는 상태이다. 저자들은 최근 경험한 선천성 후두열 2례를 video presentation과 함께 보고하는 바이다.

• Journal of the Korean Applied Science and Technology
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• 제37권6호
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• pp.1678-1686
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• 2020

This study attempted to derive the possibility of using wood pellet using rice husk, which is an agricultural byproduct, and tried to improve the lower calorific value of rice hulls thorough expansion technology and combustion additives. In the physical and chemical analysis of rice husk, the result was obtained that the chlorine content was 0.09%, which did not meet the wood pellet quality standard of Korea. When making rice hulls into expanded rice husk through the expansion technology, the chlorine content decreased, resulting in a product of 0.02%, which is equivalent to the wood pellet standard of Korea, and the calorific value was also increased to 4,280 kcal/kg compared to the existing 3,780 kcal/kg. To obtain a product of 5,000 kcal/kg or more, borax, hydrogen peroxide, and sodium hydroxide was used as combustion improver. However the improvement in calorific value was insufficient. After conversion to coffee oil path using coffee grounds, which is a waste resource biomass, it is mixed into an expanded rice husk, and when the product is analyzed, the coffee oil 15 wt% mixed product shows an excess of 4,949 kcal/kg. When using rice husk, an agricultural byproduct, as wood pellets, it is considered desirable to use waste resources to improve the calorific value, and according to the results of this study, when mixing coffee oil, rice husk can be sufficiently used as wooden pellets.

• Clinical and Experimental Pediatrics
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• 제48권11호
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• pp.1225-1231
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• 2005

Purpose : This study compares the first epileptic seizures between preterm and term-born children with periventricular leukomalacia and epilepsy. Methods : From 108 cases having lesions of high signal intensity around the ventricles in T2 weighted imaging of a brain magnetic resonance study, we selected 37 cases that showed epileptic seizures two times or more and divided them into the group of preterm-born(27 cases) and term-born children(10 cases). A retrospective study was made by comparing the two groups with regard to age, type of the first epileptic seizures, EEG findings and responsiveness to anticonvulsants. Results : The age of the first epileptic seizure was $22.2{\pm}18.3$ months in the preterm-born group and $26.9{\pm}21.1$ months in the term-born group(P=0.505). As for the first epileptic seizure, 11 out of the 27 cases in the preterm-born group had infantile spasms. Out of the 10 cases in the term-born group, 7 had complex partial seizures. In the preterm group, hypsarrhythmias were found in 11 cases, focal epileptiform discharges in 6 cases. In term-born group, focal epileptiform discharges were found in 5 cases but no epileptiform discharge was found in 3 cases. Intractable epilepsies were diagnosed in 6 cases and all of them belonged to the preterm-born group. Conclusion : More severe epilepsies such as infantile spasm and intractable epilepsies seem to be more common in preterm-born epileptic children with PVL as well as more severely abnormal EEG finding compared to term-born epileptic children.

• The Journal of Natural Sciences
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• 제5권1호
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• pp.67-75
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• 1992

In the our country, especially in Yeongil and Wolsung area, abundant authigenic zeolites are found from the tuffaceous sediments and volcanic rocks of Miocene age showing wide variation in their mineralogy and abundance from horizon to horizon. The principal zeolite species identified are clinopti-lolite. mordenite. heulandite. ferrierite, and erionite. etc. Zeolite minerals are widely used in many countries in the following applications; (a) in air separation adsorption processes; (b)as desiccants; (c)in inorganic building materials; (d)in papermaking; (e)in fertilizers; (f)as soilconditioners-this application is based upon the ability of the zeolite to ion exchange with soil nutrients; (g)in the treatment of radioactive wastes; and (h)as adsorbents for toxic gases, etc. In the present paper, using natural zeolite mordenite treated with IN hydrochloric acid or IN sodium chloride solution as column packings, separation characteristics of argon, nitrogen, carbon monoxide, and methane gases have been studied by gas chromatography. By the use of mordenite treated with hydrochloric acid solution, the tailing peak of methane showed from untreated mordenite was satisfactorily reduced, although it was difficult to separate it from carbon monoxide with a column activated at $300^{\circ}C$. Using a column activated at $350^{\circ}C$, methane could be separated from carbon monoxide easily but only carbon monoxide eluted as a bad defined peak. Mordenite treated with sodium chloride solution was generally similar to chromatograms obtained by using the untreated mordenite. Both the above chemical treatments of mordenite had little effect on the separations of argon and nitrogen. The separations and the HETP values obtained from natural zeolite mordenite treated with continuously hydrochloric acid and sodium chloride solutions were almost identical with those obtained with synthetic molecular sieve 5A zeolite. On the other hand, the efficiency of column was good in the range 20~3Oml/min of the carrier helium gas rate.

• Journal of Animal Science and Technology
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• 제45권2호
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• pp.309-318
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• 2003

In order to improve the quality of low-grade seasoned ribs, kiwi powder, pear powder and phosphates were studied. To seasoned ribs, 0.1%, 0.3% or 0.5% of kiwi powder was added and their MFI(Myofibrillar Fragmentation Index) values were 341.4, 368.3 and 405.1, respectively. As the amount of kiwi increased, MFI value increased(p<0.001). Also, when 0.5%, 1.0% or 3.0% of pear powder was added to seasoned ribs, their MFI values were increased as the addition levels of pear powder increased. As the amount of kiwi and pear powder were increased, WHC(Water Holding Capacity) decreased(p<0.001). On the other hand, as the amount of phosphates added increased, WHC increased. In drip loss, as the amount of kiwi and pear powder increased, it increased. However, drip loss was decreased as the amount of phosphates increased. For meat color, ‘L’ values of pear treatment groups were similar to those of control and ‘a’ values were higher in the treatment groups of 0.1${\sim}$0.3% kiwi powder, 0.5${\sim}$1.0% pear powder and 0.3${\sim}$0.5% phosphate than those of control. In sensory evaluation, treatment group of 0.3% kiwi powder and 0.5% phosphate showed the highest values in juiciness, tenderness and acceptability among the treatments(p<0.01).

• Magazine of the Korea Concrete Institute
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• 제6권2호
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• pp.97-107
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• 1994

The objective of this study is to develop polymer-impregnated concrete(PIC), which is a newly developed composite material made by impregnating polymer impregnanls into hardened normal concrete, and to develop analytical techniques for its proper applications. Crystalline methyl methacrylate(MMA) is chosen as a monomer of polymer impregnants. The corrlpositions of polymer impregnants and producing processes are developed by analyzing the effects of penetration, polymerization, thermal safety, and strengthening characteristics. On t he basis of experimental results of this study, various strength characteristics and stress strain constitutive relations are formulated in terms of the compressive strength of normal concrete and the polymer loadings, which can be applied for analysis and design of PIC members. In order to provide a model for fracture analysis of flexural members, fracture toughness, fracture energy, critical crack width, and tension softening relations near crack tip are also formulated in terms of member depth, initial notch depth, and the flexural strength of normal concrete. The structural analysis procedure and the finite element computer program developed in the study are applicable to evaluate elastic behavior, ultimate strength, and tension softening behavior of MMA type PIC structural members subject to various loading conditions. The accuracy and effectiveness of the developed computer program is examined by comparing the anal ytical results with the experimental results. Therefore, it is concluded that the developed structural analysis procedure and the finite element computer program are applicable to analysis and design of in-situ and precast PIC structural members.

• Journal of the Korean Institute of Gas
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• 제18권2호
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• pp.55-61
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• 2014

In this study, we evaluated the measurement of working environment, the amount of exposure, the hazards and risks of biphenyl, that was registered as 2A in IARC. Based on the exposure scenario, it was calculated that the exposure amounts are $1.0{\times}10^{-2}$, $4.2{\times}10^{-4}$, $7.0{\times}10^{-6}mg/m^3$, respectively, and the $RfC_{work}$ is 0.21, 2.13, 0.53 $0.31mg/m^3$ as carcinogenicity, target toxicity (oral), target toxicity (inhalation), developmental toxicity, respectively. According to these hazards evaluation and risk assessments, it was estimated that 0.57, 0.39 as carcinogenicity and non-carcinogenicity (developmental toxicity), respectively. It was also estimated relatively lower risks below 1. But since biphenyl is hazardous used much amounts, and could be exposed to workers directly, it was determined to require exposure monitoring to protect workers' health.

• Journal of Sericultural and Entomological Science
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• 제6권
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• pp.18-27
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• 1966

This treatise was sat up as a basic study of the artificial diets of silk worm, both nursed and wild, by storing the natural leaves in defarmentizing solution and the results obtained were as followings. 1. Defarmentizer C, a kind of defarmentizer, was developed by the author in order to store any natural diet by soaking them in the solution. 2. The defarmentizer was workable for aerophobic bacteriums, but was not effectable for aerophilic bacteriums or fungus. 3. The defarmentized diet could feed silk worm during winter season. 4. The storing method has found the importance of growthness of the diet leaves and the perfect riped leaves were found as the best condition for the purpose. 5. The perfect riped leaves were softened properly during the soaking to be fed for silk worm. 6. The defarmentizing solution has held almost the same pH value of protein isoelectric point so that the protein extraction be ceased during the soaking process. 7. The utilization of defarmentizer has found an economical value. 5. The analytical results of various wild plant leaves were found to be usable as the artificial diet mixture for general silkworm.

• Composites Research
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• 제35권6호
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• pp.456-462
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• 2022

Since natural fibers are highly flammable, it is not easy to make them flame retardant. In this study, a liquid flame retardant based on phytic acid, APTES, and Thiourea, which are flame retardant candidates derived from nature, was prepared and its performance was verified through flame retardant treatment and flame retardancy evaluation of bamboo fibers. When a liquid flame retardant is used, it is possible to treat a large amount of natural fibers with flame retardant treatment. Nine types of flame-retardant treated bamboo fibers were prepared according to the Taguchi design of experiment method. Thereafter, vertical burning test and microcalorimeter test were performed for flame retardancy evaluation, and the surface of natural fibers before and after flame-retardant treatment was compared using scanning electron microscope. The results show that phytic acid has a significant effect on improving the flame retardancy of natural fibers. Through microstructure analysis, it was assumed that the phytic acid helps flame retardant to uniformly adhere to the surface of natural fibers. If such research results are utilized, it is possible to make a large amount of natural fibers high flammability in an eco-friendly way, which is expected to be advantageous for the application of prototypes.