• 대한수학회보
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• 제51권3호
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• pp.641-651
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• 2014

Because of difficulty of using Schauder's fixed point theorem to the polynomial-like iterative equation, a lots of work are contributed to the existence of solutions for the polynomial-like iterative equation on compact set. In this paper, by applying the Schauder-Tychonoff fixed point theorem we discuss monotone solutions and convex solutions of the polynomial-like iterative equation on an open set (possibly unbounded) in $\mathbb{R}^N$. More concretely, by considering a partial order in $\mathbb{R}^N$ defined by an order cone, we prove the existence of increasing and decreasing solutions of the polynomial-like iterative equation on an open set and further obtain the conditions under which the solutions are convex in the order.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.787-790
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• 2001

Polymer bushing used for overhead line switch was designed and investigated. Requirements of electrical ratings such as partial discharge, ac withstand voltage, impulse voltage and material properties were proposed in accordance with IEEE 386 and pre-standard (PS) 151-146∼147, 170∼180 of KEPCO. The polymer bushing consists of an internal epoxy bushing and external housing made of EPDM rubber. The rubber housing was molded with mold cone. Therefore, the polymer bushing offers several advantages like light weight, good sealing properties, easy installation and excellent performance in contamination. Electric field analysis was also introduced in order to verify the reliability of the design.

• 대한심미치과학회지
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• 제10권2호
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• pp.21-30
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• 2001

Fiber reinforced materials have favorable mechanical properties. Moreover, the strength to weight ratios of this material is superior to those of most alloys. Comparing to the metals, it showed many other advantages as well, including non-corrosiveness, translucency and easy repair characteristic. Since, it has the potential for the chair-side and laboratory fabrication, it is not surprising that fiber reinforced composites offer the potential for use in various applications in dentistry. To make the well-fitted restorations, Fiber reinforced composite (FRC) has been suggested as an alternative framework material for the implant supported fixed prosthesis. Two fixed partial denture fabrication procedures were tried. Vectris fiber was pressed to the EsthetiCone gold cylinder on the implant positioned cast. And then, Targis were added on it. In the other method, we used the customized component using UCLA abutment. The beads for retaining the Vectris fiber were added on the abutment. If careful laboratory and clinical techniques were done, these two techniques would fulfill the demands of the esthetics and strength.

• Macromolecular Research
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• 제10권1호
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• pp.24-33
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• 2002

Interfacial and microfailure properties of carbon fiber/epoxy composites were evaluated using both tensile fragmentation and compressive Broutman tests. A monomeric and two polymeric coupling agents were applied via the electrodeposition (ED) and the dipping applications. A monomeric and a polymeric coupling agent showed significant and comparable improvements in interfacial shear strength (IFSS) compared to the untreated case under both tensile and compressive tests. Typical microfailure modes including cone-shaped fiber break, matrix cracking, and partial interlayer failure were observed under tension, whereas the diagonal slipped failure at both ends of the fractured fiber appeared under compression. Adsorption and shear displacement mechanisms at the interface were described in terms of electrical attraction and primary and secondary bonding forces.

• International Journal of Fluid Machinery and Systems
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• 제4권1호
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• pp.47-56
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• 2011

Our previous experimental and numerical investigations of decelerated swirling flows in conical diffusers have demonstrated that water jet injection along the symmetry axis mitigates the pressure fluctuations associated with the precessing vortex rope. However, for swirling flows similar to Francis turbines operated at partial discharge, the jet becomes effective when the jet discharge is larger than 10% from the turbine discharge, leading to large volumetric losses when the jet is supplied from upstream the runner. As a result, we introduce the flow-feedback approach for supplying the jet by using a fraction of the discharge collected downstream the conical diffuser. Experimental investigations on mitigating the pressure fluctuations generated by the precessing vortex rope and investigations of pressure recovery coefficient on the cone wall with and without flow-feedback method are presented.

• Bulletin of the Korean Chemical Society
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• 제19권7호
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• pp.770-776
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• 1998

Several ABCH type chiral calix[4]arenes were prepared from monoalkyl calix[4]arenes by treating with various acyl halide, followed by reacting with benzoyl chloride in pyridine. These asymmetrically substituted ABCH type calix[4]arenes are obtained as racemates mixture which are confirmed by the chiral shift reagent in 1H NMR spectra. The molecular and crystal structure of 5-nitro-26-allyloxy-25-benzoyloxy-28-isobutyryloxy-27-hydroxycalix[4]arene 8a has been determined by the X-ray diffraction method. Two independent enantiomeric molecules are crystallized in a 1: 1 racemate mixture. They are in the partial cone conformation in which the benzoyloxy phenyl group is down. There is a bifurcated intramolecular hydrogen bonding involving three functional groups in each molecule.

• Bulletin of the Korean Chemical Society
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• 제17권5호
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• pp.447-452
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• 1996

Three conformational isomers of calix[4]arene butanoate were isolated from the reaction of calix[4]arene and butanoyl chloride in the presence of NaH and their structures were determined by NMR spectra as 1,2-alternate 2a, partial cone 2b and 1,3-alternate conformer 2c, respectively. The crystal structure of 2a has been determined by X-ray diffraction method. The crystals are monoclinic, space group C2/c, a=18.435 (4), b=13.774 (2), c=16.941 (3) Å, β=116.23 (1)°, Z=4, V=3858.8 (12)Å3, Dc=1.21 g cm-3, Dm=1.21 g cm-3. The molecule is in the 1,2-alternate conformation. It has two-fold symmetry axis along the line connecting between C (7AA') and C (7BB') parallel to the b axis of crystal lattice.

• 충청수학회지
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• 제32권1호
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• pp.15-21
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• 2019

Let X be a reduced closed subscheme in ${\mathbb{P}}^n$ and $${\pi}_q:X{\rightarrow}Y={\pi}_q(X){\subset}{\mathbb{P}}^{n-1}$$ be an isomorphic projection from the center $q{\in}{\mathbb{P}}^n{\backslash}X$. Suppose that the minimal free presentation of $I_X$ is of the following form $$R(-3)^{{\beta}2,1}{\oplus}R(-4){\rightarrow}R(-2)^{{\beta}1,1}{\rightarrow}I_X{\rightarrow}0$$. In this paper, we prove that $H^1(I_X(k))=H^1(I_Y(k))$ for all $k{\geq}3$. This implies that Y is k-normal if and only if X is k-normal for $k{\geq}3$. Moreover, we also prove that reg(Y) ${\leq}$ max{reg(X), 4} and that $I_Y$ is generated by homogeneous polynomials of degree ${\leq}4$.

• Journal of Species Research
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• 제11권3호
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• pp.174-179
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• 2022

In this study, we identified two marine synchaetid rotifers, Synchaeta grimpei Remane, 1929 and S. vorax Rousselet, 1902, in Korea, which are the first synchaetid rotifers collected from a marine environment in the country. Prior to this study, all six synchaetids recorded in Korea were collected from freshwater environments. The morphological characteristics of both species are consistent with those recorded in previous studies of each species. Synchaeta grimpei is distinguished from other synchaetid rotifers by its cone-shaped body, wide and flat apical field, indistinct auricles, and long foot with two separated small toes. The morphological characteristics of Korean S. vorax specimens were most similar to the original description of Rousselet (1902), with its slender and cylindrical trunk shape, strongly convex apical field, and short foot with two small, separated toes. The rami of the Korean S. vorax specimen contained one frontal hook and several distinct and large teeth. Here, we provide the morphological diagnoses of the two synchaetid rotifers and the sequences of the partial mitochondrial cytochrome c oxidase subunit I (COI) of the two species.

• Journal of Korean Neurosurgical Society
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• 제62권1호
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• pp.35-45
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• 2019

Objective : To describe our experiences with a fully equipped high-end digital subtraction angiography (DSA) system within a hybrid operating room (OR). Methods : A single-plane DSA system with 3-dimensional rotational angiography, cone-beam computed tomography (CBCT), and real-time navigation software was used in our hybrid OR. Between April 2014 and January 2018, 191 sessions of cerebrovascular procedures were performed in our hybrid OR. After the retrospective review of all cases, the procedures were categorized into three subcategorical procedures : combined endovascular and surgical procedure, complementary rescue procedure during intervention and surgery, and frameless stereotaxic operation. Results : Forty-nine of 191 procedures were performed using hybrid techniques. Four cases of blood blister aneurysms and a ruptured posterior inferior cerebellar artery aneurysm were treated using bypass surgery and endovascular trapping. Eight cases of ruptured aneurysm with intracranial hemorrhage (ICH) were treated by partial embolization and surgical clipping. Six cases of ruptured arteriovenous malformation with ICH were treated by Onyx embolization of nidus and subsequent surgical removal of nidus and ICH. Two (5.4%) of the 37 cases of pre-mature rupture during clipping were secured by endovascular coil embolization. In one (0.8%) complicated case of 103 intra-arterial thrombectomy procedures, emergency surgical embolectomy with bypass surgery was performed. In 27 cases of ICH, frameless stereotaxic hematoma aspiration was performed using $XperGuide^{(R)}$ system (Philips Medical Systems, Best, the Netherlands). All procedures were performed in single sessions without any procedural complications. Conclusion : Hybrid OR with a fully equipped DSA system could provide precise and safe treatment strategies for cerebrovascular diseases. Especially, we could suggest a strategy to cope flexibly in complex lesions or unexpected situations in hybrid OR. CBCT with real-time navigation software could augment the usefulness of hybrid OR.