• 대한기관식도과학회지
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• 제10권2호
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• pp.63-67
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• 2004

Tracheomalacia can be a life threatening upper air way obstructive disease in an infant and vascular rings can be also a major rare cause of tracheoesophageal obstruction. These two rare entities can be combined in one patient because the vascular ring can cause secondary tracheomalacia during development of fetus. The diagnosis of this combination and adequate surgical correction is occasionally difficult. This is a report of an infant who had not diagnosed tracheomalacia associated with vascular ring until 5 months of age because of the prolonged tracheal intubation. The rigid bronchoscopic examination performed under impression of tracheomalacia revealed a concentric tracheal collapse, an unusual bronchoscopic findings of tracheomalacia, which raised a suspicion of the tracheal compression by vascular rings. The 3-D reconstructive DT aortography clearly demonstrated the double aortic arch. The patient was treated surgically by simple division of the left aortic arch and aortopexy with good result. The vascular ring such as double aortic arch should be considered during the diagnosis of tracheomalacia in infants. If the tracheomalacia is associated with vascular ring, simultaneous surgical correction should be performed.

• 대한수학교육학회지:수학교육학연구
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• 제23권2호
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• pp.117-133
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• 2013

수학적 오개념은 학습 부진 학생들이 올바른 수학 학습을 하는 데 큰 방해 요소 중 하나이다. 오개념의 발생을 줄이고 올바른 개념 형성을 돕고자 중학교 수학 학습에서 흔히 발생하는 수학적 오개념을 정리하여 '중학교 수학과 학습 부진 학생 지도를 위한 맞춤형 교수 학습 방법 자료'를 개발하였다. 이는 수학과 학습 부진 학생 지도를 담당한 교사들에게 교수 학습에 필요한 주요 교육 내용과 창의적이고 흥미 있는 수업 아이디어를 제공하기 위한 자료이다. 뿐만 아니라 오개념을 가진 학생들이나 학습부진아 학생들의 수업자료로 사용하거나, 교사들의 연수 자료로도 사용할 수 있을 것이다.

• 대한두개안면성형외과학회지
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• 제11권1호
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• pp.45-48
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• 2010

Purpose: After surgical interventions of mandible fractures, facial asymmetry can be occurred, and it leads to serious problems for patients. This can be solved by mandible angle ostectomy. Methods: A 19-year-old male underwent percutaneous surgical intervention for left mandibular angle and right parasymphyseal fractures 3.5 years ago. The left angle was protruded compared to the other side. Using a percutaneous approach, $4.5{\times}1cm$ sized piece of mandible angle was sawed off. For the right angle, intraoral approach was performed for angle ostectomy, and the angle was sawed off by a size of $4{\times}1cm$, using a pattern based on the piece from the left side. Results: After surgery, no complications such as subcondylar fractures, refractures, insufficient corrections, secondary angle formations, hematomas, and transient nerve palsies were seen, and symmetric correction of mandible angles were done. Conclusion: In facial asymmetries due to mandibular fractures, mandible ostectomy could be a solution. Using the bone section from the contralateral side, measurement of the amount of bone sawed off was possible, and via percutaneous approach on the previously operated site with simultaneous scar revision, and intraoral approach for the contralateral side, cosmetically satisfactory result was obtained.

• Journal of Korean Neurosurgical Society
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• 제59권3호
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• pp.233-241
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• 2016

In this review, we discuss in detail our current procedure for treating craniosynostosis using multidirectional cranial distraction osteogenesis (MCDO). The MCDO method allows all phenotypes of skull deformity to be reshaped by distraction osteogenesis, except in patients who are 5 months of age or younger and patients with posterior cranial vault problems. We report the results of clinical data of 36 children with craniosynostosis who underwent MCDO between 2005 and 2014 in our institute. This method has the following benefits, such as a high flexibility of reshaping, shorter treatment period and less invasive secondary intervention. We also discuss the other distraction osteogenesis techniques that are used to treat craniosynostosis and compare them with MCDO. The preferred procedure for correction of craniosynostosis may depend on the patient's age, the extent of deformity, and the extent of correction achievable by surgery. We can arrange the combinations of various methods according to the advantage and disadvantage of each technique.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.266-269
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• 1999

Several power factor correction(PFC) circuits are presented to achieve high PF electronic ballast for both voltage-fed and current-fed electronic ballast. The proposed PFC circuits use valley-fill(VF) type DC-link stages modified from the conventional VF circuit to adopt the charge pumping method for PFC operations during the valley intervals. In voltage-fed ballast, charge pump capacitors are connected with the resonant capacitors. In current-fed type, the charge pump capacitors are connected with the additional secondary-side of the power transformer. The measured PF and THD are higher than 0.99 and 15% for all proposed PFC circuits. The lamp current CF is also acceptable in the proposed circuits. The proposed circuit is suitable for implementing cost-effective electronic ballast.

• 대한두개안면성형외과학회지
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• 제13권2호
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• pp.130-134
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• 2012

Purpose: Brown syndrome is motility disorder of the eyeball which shows limited elevation in adduction and occurs very rarely after eye surgery. The authors have experienced a case of strabismus-like Brown syndrome combined with blepharoptosis and report this case with the review of literatures. Methods: A 28-year-old female suffered from hypotropia in the primary gaze and severe blepharoptosis with diplopia of the right eye after upper blepharoplasty. Rotation showed an inability to elevate the adducted right eye. She underwent extraocular muscle surgery about the 7 mm tucking of the right superior rectus muscle and 6 mm recession of right inferior rectus muscle. Intraoperatively, injury of the superior rectus muscle and foreign body were observed. Seven months after the extraocular surgery, the patient underwent frontalis muscle transfer on the right upper eyelid for the correction of blepharoptosis. Results: Postoperatively, the patient was orthophoric in the primary gaze, and she had improvements in the correction of blepharoptosis and eyeball movement. Conclusion: Repeated eyelid surgeries increase the risk of ocular motility disorder. Careful approach is essential for the proper treatment and successful outcome in secondary surgeries.

• The Journal of Asian Finance, Economics and Business
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• 제9권4호
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• pp.173-183
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• 2022

The objective of this research is to examine the influence of the COVID-19 pandemic on stock markets in a few developing and developed countries. This study uses daily data from January 2020 to May 2021 and obtained from World Health Organization and Thomson Reuters. The secondary data was evaluated through panel econometric methodology that includes different unit root tests, and to analyze the long-run relationship between variables, panel cointegration techniques were applied. The long-run causality among variables was examined through Panel Vector Error Correction Model. The overall findings of this study suggest a long-run association exists between several cases and death with the stock returns of the GCC and other stock markets. Furthermore, the VECM model also identified a long-run causality running from COVID cases and death towards the stock rerun of both sets of stock markets. However, a subsequent Wald test yielded mixed results, indicating no short-run causality between cases and deaths and stock returns in both groups; however, in the case of GCC, several COVID-19 cases are having a causal impact on stock markets, which is notable in light of the fact that the death rate in GCC is significantly lower than in many developed and developing countries.

• 한국지리정보학회지
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• 제26권4호
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• pp.161-172
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• 2023

자율주행차량은 차량에 장착된 다양한 센서를 통해 주행환경을 인지하고 수집된 정보를 기반으로 판단 및 제어한다. 센서 기술 및 수집된 데이터를 처리하는 알고리즘의 발달로 자율주행기술의 수준은 향상되고 있으나 완벽한 자율주행기술의 구현에는 이르지 못하고 있는 한계점을 인프라를 중심으로 하는 자율협력주행을 통해 극복하려는 움직임을 보인다. 본 연구에서는 자율주행차량의 측위를 보정할 수 있는 인프라로서 기준을 제공하는 측위 보정 표지를 개발하였다. 우선 기존의 자율주행을 위한 측위 기술 현황에 대한 분석을 수행하였다. 다음으로 정사각형의 반사면 두 개로 구성된 1차 제작물과 각 반사면의 상하 길이를 늘인 2차 제작물에 대해 포인트 클라우드 개수를 측정하는 실험을 수행하였다. 실험 결과 1차 및 2차 제작물 모두 최소 15m 거리에서 시설물을 라이다 센서로 인식할 수 있었고, 상하 길이를 확장한 2차 제작물이 1차 제작물보다 포인트 클라우드 개수도 더 많으며 시설물의 형상을 구체적으로 표현하는 것을 확인할 수 있었다.

• 전력전자학회논문지
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• 제19권1호
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• pp.91-97
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• 2014

Recently, the LED(Light Emitting Diode) is expected to replace conventional lamps including incandescent, halogen and fluorescent lamps for some general illumination application, due to some obvious features such as high luminous efficiency, safety, long life, environment-friendly characteristics and so on. To drive the LED, a single stage PFC(Power Factor Correction) flyback converter has been adopted to satisfy the isolation, PFC and low cost. The conventional flyback LED driver has the serious disadvantage of high 120Hz output current ripple caused by the PFC operation. To overcome this drawback, a new PFC flyback with low 120Hz output current ripple is proposed in this paper. It is composed of 2 power stages, the DCM(Discontinuous Conduction Mode) flyback converter for PFC and BCM(Boundary Conduction Mode) boost converter for tightly regulated LED current. Since the link capacitor is located in the secondary side, its voltage stress is small. Moreover, since the driver is composed of 2 power stages, small output filter and link capacitor can be used. Especially, since the flyback is operated at DCM, the PFC can be automatically obtained and thus, an additional PFC IC is not necessary. Therefore, only one control IC for BCM boost converter is required. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

• 대한두개안면성형외과학회지
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• 제22권4호
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• pp.193-198
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• 2021

Background: Nasal bone fractures are frequently encountered in clinical practice. Although fracture reduction is simple and correction requires a short operative time, low patient satisfaction and relatively high complication rates remain issues for many surgeons. These challenges may result from inaccuracies in fracture recognition and assessment or inappropriate surgical planning. Findings from immediate postoperative computed tomography (CT) scans and those performed at 4 to 6 weeks postoperatively were compared to evaluate the accuracy and outcomes of nasal fracture reduction. Methods: This retrospective study included patients diagnosed with nasal bone fractures at our department who underwent closed reduction surgery. Patients who did not undergo additional CT scans were excluded from the study. Clinical examinations, patient records, and radiographic images were evaluated in 20 patients with nasal bone fractures. Results: CT findings from immediately after surgery and a 1month follow-up were compared in 20 patients. Satisfactory nasal projection and aesthetically acceptable results were observed in patients with accurate correction or mild overcorrection, while undercorrection was associated with unfavorable results. Conclusion: Closed reduction surgery for correcting nasal bone fractures usually provides acceptable outcomes with relatively few complications. If available, immediate postoperative CT scans are recommended to guide surgeons in the choice of whether to perform secondary adjustments if the initial results are unsatisfactory. Based on photogrammetric data, nasal bone reduction with accurate correction or mild overcorrection achieved acceptable and stable outcomes at 1 month postoperatively. Therefore, when upward dislocation is observed on postoperative CT, one can simply observe without a subsequent intervention.