• 한국기계가공학회지
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• 제18권3호
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• pp.41-48
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• 2019

The industrial safety helmets are personal protective equipment (PPE), used to protect the head against falls from a height. This study indicated the necessity of wearing a safety helmet while working at heights below 4 m, through analysis of fall accidents occurring in the industrial field. The stress, displacement, and strain of the safety helmet shell structure have been analyzed using the finite element method with various thicknesses, engineering plastics, and designs. It was preferred that the safety helmet shell structure had a reinforcement frame of uniform thickness in terms of increased impact strength and strain energy absorption rate. The thickness can be reduced to lighten the total weight for workers wearing safety helmets.

• 반도체디스플레이기술학회지
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• 제20권3호
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• pp.51-56
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• 2021

Using an inkjet printing process, we have investigated a droplet formation of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) near the orifice of a piezoelectric inkjet head. With an attempt to form the smallest droplet without any satellites, we have applied various waveforms such as the unipolar, bipolar, and M-shaped waveforms. It is found that the droplet velocity and volume vary depending sensitively on the waveform width and voltage. Of those, the M-shaped waveform is shown to provide the smallest droplet volume, followed by the bipolar and then unipolar waveforms. The droplet printed on a PET film roll by the M-shaped waveform has the diameter as small as 46.1 ㎛. It is likely that the second short unipolar in the M-shape waveform increases the droplet velocity gradient, rendering the droplet smaller.

• 식물분류학회지
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• 제52권3호
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• pp.144-155
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• 2022

Daphne kiusiana is an evergreen shrub with dense head-like umbels of white flowers distributed in southern Korea, Japan, China, and Taiwan. Plants in China and Taiwan are recognized as var. atrocaulis by having a dark purple stem, elliptic leaves, and persistent bracts. Recently, plants on Jejudo Island were segregated as a separate species, D. jejudoensis, given their elliptic leaves with an acuminate apex, a long hypanthium and sepals, and a glabrous hypanthium. Morphological variations of three closely related taxa, the D. kiusiana complex, were investigated across the distributional range to clarify the taxonomic delimitation of members of the complex. Twelve characters of the leaf and flower were measured from digitized herbarium specimens using the image analysis program ImageJ and were included in a morphometric analysis, the results of which indicate that the level of variation in the characters is very high. The results of a principal component analysis weakly separated D. jejudoensis from D. kiusiana according to their floral characteristics, such as a longer, glabrous hypanthium, and larger sepals. However, some individuals of D. kiusiana, particularly those from Bigeumdo Island, were included in D. jejudoensis. Recognition of D. kiusiana var. atrocaulis based on the leaf shape was not supported in the analysis, and D. jejudoensis may be recognized as a variety of D. kiusiana. Our morphometric analysis shows that digitized images of herbarium specimens could be useful and an additional method by which to investigate more diverse specimens.

• 대한두개안면성형외과학회지
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• 제24권4호
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• pp.198-201
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• 2023

Maintaining the patency of the external auditory canal (EAC) during reconstruction is important because of its physiological role in hearing and immunological protective functions. The curved shape of the EAC presents a challenge when performing a skin graft. One of the key points for a successful skin graft is to ensure compression on the wound bed, and many novel methods, including prefabricated ear molds, have been reported for this purpose. In this study, we present a case of a skin graft performed to reconstruct a skin defect following excision of actinic keratosis in the EAC, using the cover of an ear thermometer probe as a mold for the graft to match the curvature of the EAC. This is an economical and practical method for secure compression dressing of a skin graft in the EAC.

• 한국의류학회지
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• 제47권1호
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• pp.137-151
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• 2023

Stationary 3D whole-body scanners generally require 5 to 20 seconds of scanning time and cannot effectively detect armpit and crotch areas. Therefore, this study aimed to analyze the accuracy of a photogrammetric technique using a multi-camera system. First, dimensional accuracy was analyzed using a mannequin scan, comparing the differences between the scan-derived measurements and the direct measurements, with an allowable tolerance of ISO 20685-1:2018. Only 2 of 59 measurement items (ankle height and upper arm circumference, specifically) exceeded the ISO 20685-1:2018 criteria. When compared with the results of the eight stationary whole-body scanners assessed by the literature, the photogrammetric technique was found to have the advantage of scanning the top of the head, armpit, and crotch areas clearly. Second, this study found the photogrammetric technique is suitable for obtaining the body scans because it can minimize the perform scanning, resulting in a reduction of measurement errors due to breathing and uncontrolled movements. The error rate of the photogrammetry method was much lower than that of stationary 3D whole-body scanners.

• 천문학회보
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• 제44권2호
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• pp.48.1-48.1
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• 2019

We found a diffuse Hα feature with a large size of ~2' around a Herbig star, MWC 1080. It shows a strong correlation with the elongated outflow cavity centered on the star. To investigate the diffuse Hα source and the molecular cavity in detail, we carried out the high-resolution NIR spectroscopy using IGRINS. We detected six hydrogen Brackett line series, seven H2 lines, and an [Fe II] forbidden line. With the obtained spatial, kinematic, and line ratio results, we discuss the characteristics of the central MWC 1080A, the NE outflow cavity, and the SE molecular cloud regions separately. Most of the bright Brγ sources around MWC 1080A were found to be reflection nebulae, but a point-like Brγ source close to another young star, MWC 1080E, was identified as a distinct source due to MWC 1080E itself. The narrow components of the H2 lines observed around MWC 1080A were found to trace PDRs located on the wall of the main outflow cavity. Based on the shock-excited H2 and [Fe II] lines detected just inside a bow-shock shape Hα feature, we suggest that it represents the actual shock at the head of the NE outflow from MWC 1080A. Also, we newly detected the shock-excited H2 and [Fe II] lines with highly blueshifted velocities in the SE molecular cloud region. They could be related to unrevealed outflows from other young stars existing around MWC 1080A.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제49권5호
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• pp.304-307
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• 2023

Venous malformation (VM) is a benign lesion of blood vessels caused by an error in vascular morphogenesis during the embryologic phase. This entity mostly affects the head and neck region, including the lips, tongue, buccal mucosa, gingiva, or palate. VM may cause functional and aesthetic impairments. The anatomical structure and shape of the lips provide an important aesthetic accent for an individual. Therefore, management of VM in the lip area without postoperative defects or scarring is challenging. In this brief communication article, we present a conservative approach to lip VM in a nine-year-old boy using a bleomycin injection that had good aesthetic and functional outcomes. Injection of 2 mL of 1/10 of 15 mg bleomycin in a saline dilution into the lip mucosa may present a drug reaction as a white plaque and reddish owl eye lesion that takes up to three weeks to resolve without a scar. It is important to recognize the characteristics and self-limiting nature of postoperative bleomycin complications to avoid unnecessary treatment.

• Steel and Composite Structures
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• 제51권1호
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• pp.63-72
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• 2024

This study delves into the interaction dynamics between lateral notches and inclusions, providing valuable insights for more effective engineering of structural components. By employing the finite element method, the research analyzes how inclusions affect the dimensions and contours of the plastic zone under confined plasticity conditions. Several parameters were investigated, including loading influence, the distance between the inclusion and notch tip, inclusion stiffness, and the distribution of Von Mises stress, as well as normal stresses σxx and σyy, and Comparison between different stresses. Examining stress distributions under varying loading conditions reveals a significant intensification, particularly near the crack tip. Moreover, the presence of an inclusion near the notch base reduces both the size and shape of the plastic zone. The distribution of the stresses for different loads knows an increase in intensity, especially near the crack head, which is the most requested by the tensile forces on its upper part, which can cause either the crack's initiation or opening, inducing significant stresses.

• Journal of Biosystems Engineering
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• 제6권2호
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• pp.9-19
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• 1982

소형(小型) 디젤엔진의 예연소실(豫燃燒室) 형상(形狀)이 저온시(低溫時)의 시동성(始動性)에 미치는 영향(影響)을 구명(究明)하기 위해 8종(種)의 예연소실(豫燃燒室)과 2종(種)의 실린더헤드를 제작(製作)하여 $2^7$ 요인실험법(要因實驗法)에 의해 1회(回) 조작시(操作時) 최저(最低) 시동가능(始動可能) 온도(溫度), 최대출력(最大出力), 전부하(全負荷)(4/4) 및 과부하(過負荷)(11/10)시(時)의 연료소비율(燃料消費率)을 측정(測定)하여 분석(分析)한 결과(結果)를 요약(要約)하연 다음과 같다. 가. 피스톤 상면(上面)에 대한 주분사구(主噴射口)의 상대각도(相對角度)가 $20^{\circ}$에서 $18^{\circ}$로 감소(減少)하면 최저(最低) 시동가능(始動可能) 온도(溫度)가 약(約) $2.4^{\circ}C$ 낮아졌으며 최대출력(最大出力)은 약(約) 0.3ps 증가(增加)되었다. 나. 실린더헤드 홈 각도(角度)가 $20^{\circ}$에서 $18^{\circ}$로 작아짐에 따라 최저(最低) 시동가능(始動可能) 온도(溫度)가 약(約) $3.3^{\circ}C$ 낮아졌으며, 최대출력(最大出力)은 약(約) 0.3ps 감소(減少)되었다. 다. 예연소실(豫燃燒室) 길이가 17.5mm에서 15.5mm로 짧아지면 최저(最低) 시동가능(始動可能) 온도(溫度)가 $2^{\circ}C$ 낮아졌으며 최대출력(最大出力)은 0.2ps정도(程度) 감소(減少)되었다. 라. 주분사구(主噴射口) 직경(直俓)이 4.8mm에서 4.5mm로 작아지면 최대출력(最大出力)은 0.2ps정도(程度) 증가(增加)했으나, 주분사구(主噴射口) 직경(直俓)만이 변화(變化)에 따른 시동성(始動性)의 차이(差異)는 인정(認定)되지 않았다. 마. 주분사구(主噴射口) 각도(角度)가 $47^{\circ}$이고 실린더헤드 홈 각도(角度)가 $18^{\circ}$일 경우(境遇) 시동가능(始動可能) 온도(溫度)가 가장 낮았으며, 주분사구(主噴射口) 직경(直俓)이 4.5mm이고 예연소실(豫燃燒室) 길이가 17.5mm일 경우(境遇) 최대출력(最大出力)도 가장 높았고, 전부하(全負荷) 및 과부하시(過負荷時)의 연료소비율(燃料消費率)도 가장 낮았다. 바. 실린더 헤드홈 각도(角度)와 주분사구(主噴射口)의 각도(角度)가 각각(各各) 시동성(始動性) 향상(向上)에 가장 큰 영향(影響)을 미쳤으며, 또한 주분사구(主噴射口) 직경(直俓)과 예연소실(豫燃燒室) 길이와의 교호작용(交互作用)이 최대출력(最大出力)에 가장 큰 영향(影響)을 미쳤으므로 이들 요인(要因)에 대한 처리수(處理數)를 늘려 시험(試驗)해 볼 필요성(必要性)이 있는 것으로 사료(思料)된다. 사. 본(本) 실험(實驗)에서 최적조건(最適條件)으로 나타난 시작(試作) 예연소실(豫燃燒室)은 기존(旣存) 예연소실(豫燃燒室)보다 약(約) $-6^{\circ}C$의 시동성(始動性) 향상(向上)을 나타냈다.

• 구강회복응용과학지
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• 제30권3호
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• pp.206-214
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• 2014

목적: 내부 원추형 연결형태 임플란트에서 지대주 나사의 좌면각도가 연결부의 기계적 안정성에 미치는 영향을 알아보기 위함이다. 연구 재료 및 방법: 원추형 연결구조 티타늄 임플란트와 시멘트 유지형 지대주, 텅스텐 카바이드 코팅된 티타늄 합금 지대주 나사를 사용하였다. 좌면각도가 $45^{\circ}$와 $90^{\circ}$를 갖는 지대주와 지대주 나사를 제작하여 30 Ncm 조임회전력으로 지대주를 체결한 후 하중을 가하고 체결 및 하중 부여에 따른 침하량을 측정하였다(n = 5). 유압식 피로시험기에 임플란트를 고정하고 스테인리스 스틸 금속관을 지대주에 합착하였다. 이 후 반복 하중을 가한 후 풀림토크 변화량을 측정하고, 압축굽힘강도와 피로강도를 측정하였다(n = 5). 결과: 지대주 침하량은 지대주나사 체결 시 가장 크게 나타났으며(P < 0.05), 나사체결과 하중부여에 따른 총 침하량은 $45^{\circ}$군보다 $90^{\circ}$군에서 더 크게 측정되었다(P < 0.05). 반복하중 부여 후 풀림 토크, 그리고 최대 압축굽힘강도와 피로강도는 통계적으로 유의한 차이를 보이지 않았다(P > 0.05). 결론: 본 실험조건하에서 지대주 나사머리의 원추형 설계가 지대주의 총 침하량을 약간 감소시키는 효과를 나타냈으나, 연결부의 전체적인 기계적 안정성에 미치는 영향은 크지 않을 것으로 판단된다.