• 공업화학
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• 제26권2호
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• pp.132-137
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• 2015

BEA형 제올라이트를 알칼리용액으로 처리하여 결정구조 내에 메조세공이 형성되도록 제조하고, 세공 내에 균일계 키랄 Co(III) 살렌을 고정화시켰다. 메조세공 BEA-제올라이트에 고정화된 이핵형 Co-$GaCl_3$ 살렌 촉매는 말단 에폭사이드의 산소고리를 카르복실산으로 여는 키랄 반응에 대하여 높은 활성을 나타내었다. 이 반응을 통하여 라세믹 에폭사이드로부터 다양한 모노 에스테르 유도체를 중간 정도의 광학선택도(47~69 ee%)로 합성할 수 있었다. 키랄(S)-ECH를 반응물로 사용하면, 이들은 키랄 살렌 촉매 존재하에서 카르복시 산에 의하여 에폭사이드의 링이 광학선택적으로 열리며, 생성된 화합물을 염기용액에서 탈염산 처리하면 다시 에폭사이드 링이 형성되면서 광학순도가 매우 높은 모노에스터 에폭사이드 (R)-GB (98 ee% 이상)가 얻어졌다. 고정화촉매는 매우 용이하게 제조될 수 있었으며, 특별한 재생처리 없이 여러번 재사용하여도 촉매의 활성이 유지되었다.

• 한국지반공학회논문집
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• 제36권1호
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• pp.29-38
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• 2020

최근 환기구, 비상탈출용 수직구, 취수탑 가시설 등 지중 가물막이 또는 차수벽체로 원형 가물막이가 많이 적용되고 있다. 원형단면의 경우 벽체에 작용하는 토압이 원형가물막이 형상에 따라 아칭효과(arching effect)로 인하여 작용토압에 대한 구조체의 부재력이 감소하는 것으로 알려져 있다. 본 연구에서는 원형 가물막이에 대한 2D 유한요소해석(FEM)을 활용하여 원형띠장(ring beam) 강성을 산출 후 탄소성해석에 적용하여 부재의 단면력을 검토하였다. 더불어 3D 유한요소해석(FEM)을 통하여 원형단면의 가물막이가 다각형 형태의 가물막이보다 전단력, 휨모멘트, 그리고 발생변위가 최소값을 갖는 것으로 나타났으며, 이로써 원형단면 가물막이가 구조적으로 보다 효율적인 단면 형태임을 확인하였다

• Advances in pediatric surgery
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• 제16권2호
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• pp.101-107
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• 2010

Herniorrhaphy of Indirect inguinal hernia (IIH) is one of the most frequently performed surgical procedures in children. The overall incidence of inguinal hernias in childhood ranges from 0.8 to 4.4 %. The incidence is up to 10 times higher in boys than girls, especially much higher in premature infants. IIHs in children are basically an arrest of embryologic development rather than an acquired weakness, which explains the increased incidence in premature infants. In normal development, the processus vaginalis closes, obliterating the peritoneal opening of the internal ring between 36th and 40th week of gestation. This process is often incomplete, leaving a small patent processus in many newborns. However, closure continues postnatally, and the rate of patency is inversely proportional to age of the child. The presence of a patent processus vaginalis is a necessary but not sufficient variable in developing a congenital IIH. In other words, all congenital IIHs are preceded by a patent processus vaginalis, but not all patent processus vaginalis go on to become IIHs. The overall incidence of IIH in population is approximately 1 to 2 % and the incidence of a processus vaginalis is approximately 12 to 14%, clinically appreciable IIH should develop in approximately 8 to 12 % of patients with a patent processus vaginalis. Although the classic open inguinal hernia repair remains the gold standard for most pediatric surgeons, laparoscopic repair is being performed in many centers. Like open technique, laparoscopic technique is fundamentally a high ligation of the indirect hernia sac with or without internal ring ligation. The advantages of laparoscopic approach include the ease of examining the contralateral internal ring, the avoidance of access damage to vas and vessels during mobilization of cord, decreased operative time, and an ability to identify unsuspected direct or femoral hernias. Almost all groin hernias in children are IIHs and occur as a result of incomplete closure of processus vaginalis. The treatment is repair by high ligation of hernia sac, which can be done by an open or laparoscopic technique. The contralateral side can be explored by laparoscopy or left alone, open exploration is no longer indicated due to potential risk of infertility.

• 한국의류학회지
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• 제20권6호
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• pp.1084-1095
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• 1996

The purpose of this study was to compare the effect of clothing materials and the opening of the garment on the microclimate of the skin simulating system during the coupled heat and moisture transfer. To determine the effect of size and location of openness of the garment, openness was simulated by removing parts of the spacer ring of the modelling system. To evaluate the changes of humidity and temperature of air layer in the system, buffering indice, Kd and Pr, and efficiency of openness were determined. When the openness was imparted to the system, the transport rate of heat and moisture increased abruptly; at the total openness of 26.4%, which simulated the openness of neck, armhole and waist, Kd increased at least more than three times of the closed system. As the openness increased, the effect of clothing materials decreased gradually to lose its effect at the 60% openness and approached the value of nude. Temperature regulating index showed, however, higher value than nude which was apparently due to the still air layer.

• Bulletin of the Korean Chemical Society
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• 제27권3호
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• pp.345-354
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• 2006

Ionic liquids are alternative reaction media of increasing interest and are regarded as an eco-friendly alternatives, of potential use in place of the volatile organic solvents typically used in current chemical processing methods. They are emerging as the smart and excellent solvents, which are made of positive and negative ions that they are liquids near room temperature. The nucleophilic substitution reaction is one of the important method for inserting functional groups into a carbon skeleton. Many nucleophilic substitution reactions have been found with enhanced reactivity and selectivity in ionic liquid. In this review, some recent interesting results of nucleophilic substitution reactions such as hydroxylations, ether cleavages, carbon-X (X= carbon, oxygen, nitrogen, fluorine) bond forming reactions, and ring opening of epoxides in ionic liquids are discussed.

• Bulletin of the Korean Chemical Society
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• 제32권spc8호
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• pp.2965-2969
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• 2011

Highly efficient and rapid aminolysis of epoxides with various amines in water under microwave irradiation in the absence of catalyst was developed. Chiral ${\beta}$-amino alcohols were formed in a short time with excellent yields.

• 약학회지
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• 제36권6호
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• pp.604-610
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• 1992

Synthesis of 6-aza-2´-azido-2´,3´-secouridine, 6-aza-2´,3´-diazido-2´, 3´-secouridine, and 6-aza-5´-azido-2´,3´-secouridine as potential antiviral agents is described. These acyclic nucleosides were synthesized from uridine by the method of ring opening reaction of sugar moiety. And these compounds were tested against HSV-1 and HSV-2, but the in vitro test results of these compounds were negative.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2002년도 봄 학술발표회 논문집
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• pp.352-354
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• 2002

A series of ABA type triblock copolymers of trimethylene carbonate (TMC) and $\varepsilon$-caprolactone($\varepsilon$-CL) with different molar ratio were synthesized using ethylene glycol as initiator and stannous octoate as catalyst by ring-opening bulk polymerization. The characterization of the triblock copolymers was characterized by $^1$H-NMR, $\^$13/C-NMR, FT-IR, GPC and DSC, and compared with random copolymer. (omitted)

• Journal of Photoscience
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• 제10권3호
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• pp.241-243
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• 2003

Photoreactions of some carbonyl compounds with TiO$_2$ were investigated in methanol. Although 1,3-cyclohexanedione and phthalimide afforded 3-methoxy-2-cyclohexen-l-one and 3-methoxy-1-isoindolinone, respectively, acid anhydrides such as succinic, phthalic, and maleic anhydrides gave the monoesters of dicarboxylic acids in good to excellent yields, when they were irradiated on TiO$_2$ in methanol with 300 nm UV light.

• Macromolecular Research
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• 제11권6호
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• pp.511-513
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• 2003

Hydroxyl groups were introduced onto the surface of a silicon wafer by O$_2$ plasma treatment. Poly(l-lactide) (1-PLA) was attached onto the surface-modified silicon wafer by the ring-opening polymerization of l-lactide using the hydroxyl group as an initiator. Lamellar single crystals of 1-PLA were grown directly on the 1-PLA-attached silicon wafer from a 0.025% solution in acetonitrile at 5$^{\circ}C$. A well-separated, lozenge-shaped, monolayered lamellar single crystal was prepared because the 1-PLA-attached silicon wafer acts as an initial nucleus.