• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.6
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• pp.649-654
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• 2010

A three-dimensional numerical study of the WIG-effect vehicle with a direct-underside-pressurization (DUP) system and a propeller is performed to analyze the aerodynamic forces and moments acting on the vehicle. The computational model includes all the compartments of a WIG-effect vehicle, including a propeller in the middle of the fuselage and an air chamber under the fuselage. The DUP system and propeller help considerably reduce the take-off speed and minimize the effect of the hump drag when the vehicle accelerates to take off on water. The airflow is accelerated by a propeller, and the air then enters the air chamber through a channel in the middle of the fuselage, this air helps increase the lift since the dynamic pressure of air is converted to static pressure. However, the air accelerated by the propeller produces excessive drag and creates yawing moment. It is found that the effect of yawing and rolling moments on static stability is negligible.

• Archives of Craniofacial Surgery
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• v.11 no.2
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• pp.77-84
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• 2010

Purpose: The nasal bones are the most common fracture sites of the facial bones, and a careful reduction may still result in secondary deformities, such as saddle nose, deviated nose, hump nose etc, requiring secondary cosmetic rhinoplasty. Therefore, this study examined the clinical characteristics of nasal bone fractures to propose guidelines for patient selection and surgical procedures to achieve more satisfactory results and to prevent secondary deformities with simultaneous augmentation rhinoplasty and bony reduction. Methods: The study was based on 26 out of 149 nasal bone fracture patients who underwent simultaneous augmentation rhinoplasty with bony reduction between May 2008 and April 2009. Retrospective analysis was performed according to the clinical data, surgical techniques and postoperative results. Results: Of the 26 patients, there were 15 males and 11 females. The incidence according to the Stranc's classification revealed that 62% of patients were injured by a frontal impact and 38% by a lateral impact. Frontal impact plane I (50%) was the most frequent type. At the follow up, 18 (81.2%) out of 22 patients were satisfied with their postoperative outcome, and the remaining 4 patients were fair. No one was dissatisfied. However, 5 cases in 3 patients (23%) had some complications; minimal implant deviation in 2 cases, minor irregularity on the nasal dorsum in 2 cases and palpable implant movement under palpation in 1 case. None of these cases required surgical correction. Conclusion: With the proper guidance, simultaneous augmentation rhinoplasty with bony reduction can prevent secondary deformities and satisfy the cosmetic outcomes.

• Journal of the Korean Ceramic Society
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• v.44 no.2 s.297
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• pp.110-115
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• 2007

The effects of $TiO_2$ in the glasses on the shrinkage and dielectric properties of BNT-glass composites have been investigated. Without $TiO_2$ addition, BNT-glass composite showed two humps in the shrinkage curve, which are related with crystallization of $BaTi(BO_3)_2\;and\;Bi_4Ti_3O_{12}$. However, the increase of $TiO_2$ addition resulted in the decrease of 2nd hump in the shrinkage. The increased dielectric constant with $TiO_2$ addition might be due to the reduced crystallization of $Bi_4Ti_3O_{12}$. A dielectric constant of 52, a quality factor of 5088 GHz, and a temperature coefficient of resonant frequency of $-0.16ppm/^{\circ}C$ were obtained for a specimen containing $TiO_2$-added glasses, without sacrificing the benefits of high ${\varepsilon}_r$ and low TCF of BNT ceramics.

• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.548-559
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• 2016

Recent interests in both vehicle emissions and public health have facilitated the development of more eco-friendly transportation systems. This study proposed an integrated simulation approach for evaluating the effectiveness of speed management strategies from the various perspectives including safety, operational efficiency, and environmental compatability. Those simulation methods include driving simulation, traffic flow simulation, emissions simulation, and air dispersion simulation. An essence of the proposed simulation framework is to create the systematic connection of each simulation method toward the evaluation of effectiveness of speed management strategies. As an example, chicane and speed hump in residential area were evaluated by the proposed method. It is expected that the proposed simulation-based approach would be effectively used for the decision-making process in selecting better alternatives considering both safety and public health.

• Archives of Plastic Surgery
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• v.38 no.6
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• pp.755-760
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• 2011

Purpose: Correction of cleft lip nose deformity (CLND) in adulthood is different from one in childhood. Usually correction of CLND is final surgery for adult patient who has cleft lip, so many things have to be considered for correction. Of course, it is different from common rhinoplasty, either. The adult patients can be corrected by complete rhinoplasty with various techniques. To recognize how rhinoplasty techniques was used for correction of CLND, authors analyzed detailed techniques which were selected in the adult patients for 10 years and reviewed comprehensive operation. Methods: A retrospective review was conducted involving 64 patients with CLND who underwent surgery and aged after 14 years at operation between 2001 and 2010. Detailed techniques were investigated by medical record review and classified according to incision, septoplasty, osteotomies, correction of vault, tip plasty and etc. Results: Except one, all patients were performed open rhinoplasty. 49 patients were performed septoplasty. 33 patients were performed complete rhinoplasty with osteotomies. Hump nose correction was performed for 10 patients. Dorsal augmentation was performed for 8 patients. And all patients were performed tip plasty. Tip plasty using suture technique was performed for 58 patients and graft was performed for 48 patients. Conclusion: Correction of CLND in adult is one of the most challenging and varied operation of plastic surgery. In this study, the majority of patients were performed complicated and delicated procedures. It seems to be because patient's demand level has been elevated and rhinoplasty procedures have been advanced. This study may help to planning of CLND correction.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.3
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• pp.143-147
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• 2002

Granule cells in dentate gyrus of hippocampus relay information from entorhinal cortex via perforant fiber to pyramidal cells in CA3 region. Their electrical activities are known to be closely associated with seizure activity as well as memory acquisition. Since action potential is a stereotypic phenomena which is based on all-or-none principle of $Na^+$ current, the neuronal firing pattern is mostly dependent on afterpotentials which follows the stereotypic $Na^+$ spike. Granule cells in dentate gyrus show afterdepolarization (ADP), while interneurons in dentate gyrus have afterhyperpolarizaton. In the present study, we investigated the ionic mechanism of afterdepolarization in hippocampal dentate granule cell. Action potential of dentate granule cells showed afterdepolarization, which was characterized by a sharp notch followed by a depolarizing hump starting at about $-49.04{\pm}1.69\;mV\;(n=43,\;mean{\pm}SD)$ and lasting $3{\sim}7$ ms. Increase of extracellular $Ca^{2+}$ from 2 mM to 10 mM significantly enhanced the ADP both in amplitude and in duration. A $K^+$ channel blocker, 4-aminopyridine (4-AP, 2 mM), enhanced the ADP and often induced burst firings. These effects of 10 mM $Ca^{2+}$ and 4-AP were additive. On the contrary, the ADP was significantly suppressed by removal of external $Ca^{2+},$ even in the presence of 4-AP (2 mM). A $Na^+$ channel blocker, TTX (100 nM), did not affect the ADP. From these results, it is concluded that the extracellular $Ca^{2+}$ influx contributes to the generation of ADP in granule cells.

• Journal of Astronomy and Space Sciences
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• v.28 no.2
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• pp.109-116
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• 2011

The first presented BV light curves of BH UMa confirmed Krajci's (2005) result that BH UMa is an RR Lyr star that belongs to the RRc subgroup. The light curves showed a slight asymmetry of D = 0.453 with an amplitude of about $0.^m58$ in B, $0.^m47$ in V, and $0.^m11$ in B-V and with a small hump between $0.^p82$ and $0.^p86$. We determined nine new times of minimum light and eight times of maximum light. We also analyzed all of the available unanalyzed minimum timings and found for the first time that the period of BH UMa has varied dramatically in at least three independent sinusoidal ways superposed on a secularly downward parabola over 66 years. The secular period decreasing rate was obtained as $6.^d684{\times}10^{-8}y^{-1}$, corresponding to -0.58 s/century. The semi-amplitude and period for each of the three sinusoidal variations were ($0.^d058$, $14.^y44$), ($0.^d044$, $9.^y98$), and ($0.^d005$, $0.^y97$), respectively. It is uncertain whether the periodicity for the shortest period of $0.^y97$ is real or spurious. The secular period decrease, well consistent with those of the other RRc stars, could be considered as a natural result of the evolution of the BH UMa system. The two possible sinusoidal terms were interpreted as both two light-time effects due to two additional bodies orbiting BH UMa and combinations of random fluctuations in the pulsation period of BH UMa. Two interpretations were shortly discussed with related parameters.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.71-76
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• 2018

The purpose of this study is to analyze the factors affecting the roundabout accidents near schools. This study gives particular attentions discussing characteristics by pedestrian accident severity using the ordered logit models. In pursuing the above, 63 roundabouts installed before 2014 are surveyed for modeling. the traffic accident data from 2014 to 2016 are collected from TAAS data set of Road Traffic Authority. Such 35variables explaining the accidents as environment, human, geometries, school and roundabout factor are selected from literature reviews. The main results are as follows. First, the ordered logit models (${\rho}^2$ of 0.272, $x^2$ of 24.723) which is statistically significant have been developed. Second, environment factor variable is analyzed to be day or night ($X_1$ ), human factor variables are evaluated to be driver gender($X_4$), older driver($X_5$), pedestrian gender($X_7$) and children pedestrian($X_8$ ). Third, geometries factor variable are analyzed to be speed limit sign($X_{16}$) and median barrier($X_{21}$), school factor variables are evaluated to be hump-type crosswalk($X_{25}$), CCTV($X_{26}$) and school zone sign($X_{27}$), roundabout factor are analyzed to be roundabout sign($X_{30}$) and number of circulatory roadway lane($X_{32}$). Finally, this study could give some implications to decreasing the accidents severity at roundabout near schools.

• Archives of Craniofacial Surgery
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• v.9 no.2
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• pp.77-80
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• 2008

Purpose: The majority of nasal fractures have been treated by closed reduction. And they were manipulated under local anesthesia or general anesthesia. Under the local anesthesia, patients can feel the pain and fear, so general anesthesia through the endotracheal intubation became popularized recently to treat the nasal fracture. But it has still the drawbacks of postanesthetic complication. Therefore, under the mask ventilation anesthesia using oral airway, we tried to manipulate the nasal fracture. Methods: From July 2007 to November 2007, we worked with fifty patients that were manipulated the nasal fracture. Fifty patients were divided into two groups, general anesthesia with the endotracheal intubation group(n=25) and the mask ventilation using oral airway group(n=25). We checked up the anesthesia time, postanesthetic complication, postoperative aesthetic & functional problem of nose in two groups. Results: In total operation time and sore throat frequency among the postoperative anesthetic complications, there was statistically significant difference between the mask ventilation group and the endotracheal intubation group(p<0.05). But there was no difference statistically in nausea frequency(p>0.05). And no patients complained of postoperative nasal complication such as septal deviation, septal perforation, nasal obstruction and hump nose in two groups. Conclusion: Through the mask ventilation using oral airway, we could reach satisfactory results in the anesthetic time and postanesthetic complication.

• Archives of Craniofacial Surgery
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• v.9 no.2
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• pp.62-66
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• 2008

Purpose: Although nasal fractures are often discussed as minor injuries but the incidence of post-traumatic nasal deformity remains high. For decrease the incidence of post-traumatic nasal deformity which require the guideline to optimize the management of acute nasal bone fracture. The aim of this study is analysis of post-traumatic nasal deformity according to Stranc classification. Method: We reviewed 310 patients with nasal bone fracture treated at our hospital from January of 2005 to December of 2006. Result: Post-traumatic complication were divided septal deviation, nasal bone deformity, temporary hyposmia and synechia. Nasal bone deformity include nasal bone deviation, hump, flat nose and minimal nasal bone irregularity. The incidence of total complication rate was 36.4%. The most common complication was nasal deformity(22.9%) followed by septal deviation(19.7%). The most common complication was septal deviation(20%) in frontal impact. The most common complication was nasal deformity(19.5%) in lateral impact. In frontal impact, the incidence of complication rate was plane II(68.8%) followed by plane I(29.9%) and plane III(16.7%). In lateral impact, the incidence of complication rate was plane II (78.8%) followed by plane III(61.5%) and plane I(42.7%). Conclusion: This result can be used to improve longterm results and to reduce the incidence of post-traumatic nasal deformity by predict complication of nasal bone fracture according to Stranc classification.