• 한국인터넷방송통신학회논문지
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• 제12권2호
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• pp.61-68
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• 2012

최근 디지털 컨텐츠와 컨텐츠 사용자의 기하 급수적인 증가와 함께 recommender 시스템이 주목을 받으며 많은 응용 프로그램에 적용되고 있는 가운데, recommender 시스템의 확장성과 대체적으로 이와 반비례하는 정확성이 이슈가 되고 있다. 본 논문에서는 recommender 시스템 모델 중 하이브리드 모델의 매트릭스를 제거하고 아이템의 특성을 정하기 위해 클러스터링 기술을 사용한 Scalable Hybrid Recommender System을 제안한다. 제안된 모델은 recommender 시스템의 확장성과 정확성을 향상시키기 위해서 아이템에 대한 사용자의 평가 정보, demographic 정보와 구체적인 시간 정보를 사용한다. Reduction 기술 사용을 통해 Item-feature 매트릭스의 사이즈를 축소하고, 사용자 demographic 정보를 사용하여 temporal aware hybrid user model을 만든 후, 비슷한 정보를 가진 사용자간 클러스터링을 통해, 가장 유사한 정보를 가진 사용자들을 추출하여, 사용자간 정보를 비교함으로써 사용자가 원하는 아이템의 특성을 예상하고 사용자에게 N개의 아이템을 추천함으로써, 기존의 recommender 시스템보다 더욱 향상된 결과를 도출해 낼 수 있는 알고리즘을 제시하였다.

• Archives of Plastic Surgery
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• 제42권4호
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• pp.446-452
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• 2015

Background Various techniques are used for performing breast reduction. Wise-pattern and vertical scar techniques are the most commonly employed approaches. However, a vertical scar in the mid-lower breast is prominent and aesthetically less pleasant. In contrast, a semicircular horizontal approach does not leave a vertical scar in the mid breast and transverse scars can be hidden in the inframammary fold. In this paper, we describe the experiences and results of semicircular horizontal breast reductions performed by a single surgeon. Methods Between September 1996 and October 2013, our senior author used this technique in 38 cases in the US and at our institution. We used a superiorly based semicircular incision, where the upper skin paddle was pulled down to the inframammary fold with the nipple-areola complex pulled through the keyhole. Results The average total reduction per breast was 584 g, ranging from 286 to 794 g. The inferior longitudinal pedicle was used in all the cases. The average reduction of the distance from the sternal notch to the nipple was 13 cm (range, 11-15 cm). The mean decrease in the bra cup size was 1.7 cup sizes (range, a decrease of 1 to 3). We obtained very satisfactory results with a less noticeable scar, no complication such as necrosis of the nipple or the skin flap, wound infection, aseptic necrosis of the breast tissue, or wound dehiscence. One patient had a small hematoma that resolved spontaneously. Conclusions This technique is straightforward and easy to learn, and offers a safe, effective, and predictable way for treating mammary hypertrophy.

• 방송공학회논문지
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• 제8권3호
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• pp.238-249
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• 2003

국내 지상파 디지털멀티미디어방송(DMB)의 전송규격으로 OFDM 기반의 Eureka 147 DAB 시스템이 채택되었다 OFDM은 단일반송파 변조에 비해 많은 장점을 가지고 있으나, 높은 PAPR(Peak-to-Average Power Ratio)로 인해 A/D 및 D/A 변환기의 복잡도의 증가 및 고출력 증폭기의 효율 감소의 원인이 된다. 이와 같은 OFDM의 높은 PAPR을 감소시키기 위해 clipping, peak windowing, companding, SLM(Selected Mapping), PTS(Partial Transmit Sequences) 등과 같은 다양한 기법들이 제안되었다. 본 논문에서는 SLM과 PTS의 효율적인 구현방법을 제안하고, 이를 적용한 DMB 시스템의 PAPR 감소 성능에 대한 평가를 수행하였다 모의실험 결과, 제안된 MSLM(Modified SLM)은 SLM과 동일한 성능을 유지하면서 $P^{(U)}$벡터수의 감소로 인해 계산량 및 하드웨어 복잡도가 경감되는 이점이 있는 것으로 나타났으며, MPTS(Modified PTS) 또한 동일한 조건 하에서 PTS보다 우수한 PAPR 감소 성능을 보였다.

• 대한두개안면성형외과학회지
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• 제15권2호
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• pp.53-58
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• 2014

Background: Maxillomandibular fixation (MMF) is usually used to treat double mandibular fractures. However, advancements in reduction and fixation techniques may allow recovery of the premorbid dental arch and occlusion without the use of MMF. We investigated whether anatomical reduction and microplate fixation without MMF could provide secure immobilization and correct occlusion in double mandibular fractures. Methods: Thirty-four patients with double mandibular fractures were treated with open reduction and internal fixation without MMF. Both fracture sites were surgically treated. For bony fixations, we used microplates with or without wire. After reduction, each fracture site was fixed at two or three points to maintain anatomical alignment of the mandible. Interdental wiring was used to reduce the fracture at the superior border and to enhance stability for 6 weeks. Mouth opening was permitted immediately. Results: No major complications were observed, including infection, plate exposure, non-union, or significant malocclusion. Five patients experienced minor complications, among whom the only one patient experienced a persistant but mild malocclusion with no need for additional management. Conclusion: This study showed that double mandibular fractures correction with two-or three-point fixation without MMF simplified the surgical procedure, increased patient comfort, and reduced complications, due to good stability and excellent adaptation.

• 한국방사선학회논문지
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• 제13권2호
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• pp.227-232
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• 2019

자기공명영상에서 금속 물질이 삽입된 환자에서 자기감수성에 의한 허상이 발생하여 영상의 진단적 가치가 저하되는 문제가 발생하고 있다. 여러 가지 인공물 감소기법 중 VAT-SEMAC 기법을 적용하여 영상의 왜곡에 대해 연구 하였다. 정형외과 수술시 사용되는 금속 임플란트를 팬텀에 부착하여 T1WI, T2WI를 스캔 시 허상으로 인한 왜곡을 측정하였다. 감소기법의 미적용, VAT 적용, VAT-SEMAC을 호환 적용하여 검사를 실시한 후 허상을 비교 분석 하였다. 허상은 VAT-SEMAC에서 최소 8%에서 최대 26%의 감소를 보였다. VAT-SEMAC 기법을 적용하면 정형 보철물이 삽입된 환자에게도 영상의 질을 향상시켜 진단적 가치가 향상된 영상을 획득할 수 있다. 적절한 스캔시간과 영상의 질을 동시에 고려한다면 실제 임상에서 VAT-SEMAC의 적용하여 허상 감소효과를 얻을 수 있을 것이다.

• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.46.1-46.10
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• 2018

Objectives: This study was to evaluate the antibacterial effect of different instrumentation and irrigation techniques using confocal laser scanning microscopy (CLSM) after root canal inoculation with Enterococcus faecalis (E. faecalis). Materials and Methods: Mesiobuccal and mesiolingual canals of extracted mandibular molars were apically enlarged up to a size 25 hand K-file, then autoclaved and inoculated with E. faecalis. The samples were randomly divided into 4 main groups according to the system of instrumentation and irrigation: an XP-endo Shaper (XPS) combined with conventional irrigation (XPS/C) or an XP-endo Finisher (XPF) (XPS/XPF), and iRaCe combined with conventional irrigation (iRaCe/C) or combined with an XPF (iRaCe/XPF). A middle-third sample was taken from each group, and then the bacterial reduction was evaluated using CLSM at a depth of $50{\mu}m$ inside the dentinal tubules. The ratio of red fluorescence (dead cells) to green-and-red fluorescence (live and dead cells) represented the percentage of bacterial reduction. The data were then statistically analyzed using the Kruskal-Wallis test for comparisons across the groups and the Dunn test was used for pairwise comparisons. Results: The instrumentation and irrigation techniques had a significant effect on bacterial reduction (p < 0.05). The iRaCe/XPF group showed the strongest effect, followed by the XPS/XPF and XPS/C group, while the iRaCe/C group had the weakest effect. Conclusions: Combining iRaCe with XPF improved its bacterial reduction effect, while combining XPS with XPF did not yield a significant improvement in its ability to reduce bacteria at a depth of $50{\mu}m$ in the dentinal tubules.

• 한국소음진동공학회논문집
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• 제13권5호
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• pp.357-363
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• 2003

There have been lots of studies on noise transmission analysis and noise reduction In ducts. In order to reduce the noise transmission in ducts. active noise cancellation techniques have often been employed and a rotation shaft with blades has sometimes been suggested. These Ideas were not successfully commercialized because of the limitation of real life such as size or application difficulties. This study investigated how a rotational shaft with blades could reduce the noise transmission in a duct. To do so, an assembly of the shaft and the $haft housing was built In the middle of a duct. and the clearance between the blades and the housing was 0.2 mm. The noise reduction was experimentally evaluated with respect to the number of blades. the rotation speed, and the rotation or stop. This paper showed that the noise reduction resulted in about 14∼19 dBA regardless of the three test conditions only If the blades always blocked the duct. And. the noise reduction increased due to the higher number of blades and the lower speed of the shaft.

• 한국세라믹학회지
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• 제55권4호
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• pp.381-391
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• 2018

In this work, photocatalytic $CO_2$ reduction over a CdSe-graphene-$TiO_2$ nanocomposite has been studied. The obtained material was successfully fabricated via ultrasonic technique. The physical properties of the as-synthesized materials were characterized by some physical techniques. The $TiO_2$ and CdSe dispersed graphene nanocomposite showed excellent results of strong reduction rates of $CO_2$ compared to the results of bare $TiO_2$ and binary CdSe-graphene. An outstanding point of the combination of CdSe-$TiO_2$ and graphene appeared in the form of great photocatalytic reduction capability of $CO_2$. The photocatalytic activity of the asfabricated composite was tested by surveying for the photoreduction of $CO_2$ to alcohol under UV and visible light irradiation, and the obtained results imply that the as-prepared CdSe-graphene-$TiO_2$ nanocomposite is promising to become a potential candidate for the photocatalytic $CO_2$ reduction.

• Journal of Korean Neurosurgical Society
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• 제30권sup1호
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• pp.159-164
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• 2001

Reduction cranioplasty is one of the treatment modality among many treatment options for macrocephaly with hydrocephalus. The most previous techniques of reduction cranioplasty have some disadvantages such as difficult airway maintenance, pressure sore due to modified prone position, severe venous infarct due to obstruction of venous blood flow and large amount of bleeding from the dissection of superior sagittal sinus to obtain bone fragment needed. A 28-month-old girl had extreme macrocephaly. She couldn't control head rotation and keep sitting position. The operation was performed at supine position with adequate exposure of entire calvarium and the hinge was made in occipital bone fragment that covered posterior part of superior sagittal sinus. Bleeding volume and the other complications were decreased and acceptable reduction was achieved with this method.

• 웰빙융합연구
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• 제5권2호
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• pp.21-27
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• 2022

Purpose: This study is about photocatalytic technology and plasma oxidation-reduction technology. To the main cause of exposure to odor pollution, two deodorization techniques were applied to develop a module with higher removal efficiency and ozone reduction effect. Research design, data and methodology: A composite module was constructed by arranging two types of dry deodorization equipment (catalyst, adsorbent) in one module. This method was designed to increase the responsiveness to the components of complex odors and the environment. standard, unity, two types of oxidizing photo-catalyst technology and plasma dry deodorization device installed in one module to increase the potential by reduction to 76% of ozone, 100%, and 82%. Results: The complex odor disposal efficiency was 92%. Ammonia was processed with 50% hydrogen sulfide and 100% hydrogen sulfide, and ozone was 0.01ppm, achieving a target value of 0.07ppm or less. The combined odor showed a disposal efficiency of 93%, ammonia was 82% and hydrogen sulfide was 100% processed, and ozone achieved a target value of 0.07 ppm or less. Conclusions: Ozone removal efficiency was 76% by increasing Oxidation-Reduction Reaction(ORR). The H2S removal efficiency of the deodorizer was higher than that of the biofilter system currently used in sewage disposal plants.