• Journal of Korean Academy of Dental Administration
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• v.7 no.1
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• pp.21-28
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• 2019

The purpose of this study was to investigate the association between wrong postures and pain during scaling and encourage dental hygienists and students to exercise scaling in a good position. After obtaining informed consent, 107 students (3rd and 4th grade students) who had an experience with scaling practice were enrolled. The questionnaire included three general items, four items related to the posture during scaling, and nine items related to pain management (total 16 items), for which the five-point Likert scale was used. Through the questionnaire, we examined the preference of posture during scaling, posture education during scaling, pain in each part during scaling, pain management, and pain management method. In the scaling exercise, 86.3% of the subjects were instructed on the correct posture, and 87.9% of the subjects perceived the possibility of inducing musculoskeletal disorders based on the scaling posture. The percentage of subjects who responded that they performed scaling in the correct posture was 33.6% and that of subjects who answered that they bowed or turned their head by more than 15° was 64.4%. Further, 45.7% of the subjects answered that they bent their shoulders, and 29.9% of the subjects answered that their postures were not parallel to the floor. Pain during scaling was still higher when they bent their head, they bent their waist, and they bent their wrist (p<0.05). During scaling, pain was most frequent in the fingers and hands (15%), followed by the neck (14%), shoulders (11.2%), waist (9.3%), and feet and legs (2.8%). The percentage of subjects who performed regular exercise (or stretching) to prevent pain was 29.9% and that of subjects who managed pain after scaling was 12.1%. Further, exercise (24.6%) and self-massage (20.3%) were highly used as the pain management methods, and the school practice was preferred to education media for pain management (79.4%). In the scaling practice, there was a training on pain management, but the frequency of practicing in the wrong posture was high. Moreover, pain increased upon practicing in an incorrect posture. Therefore, more in-depth and systematic education on the necessity and method of musculoskeletal disease management during scaling is required.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.4
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• pp.198-205
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• 2023

We investigated the effects of Al and Mg on the microstructure and hardness of the coating layer of galvanized steel sheets, by thermodynamic calculations, X-ray diffraction, scanning electron microscopy, and Vickers hardness tests of Zn-0.2Al, Zn-6Al-2Mg, and Zn-10Al-5Mg coating layers. Regardless of the alloy composition of the galvanizing bath, a Fe-Al layer was observed between the coating layer and steel sheet. The Zn-0.2Al coating layer consists of major h.c.p. Zn phase and minor f.c.c. Al phase. The fraction of f.c.c. Al phase (containing a significant amount of Zn) of the coating layer increases with increasing the chemical composition of Al of the galvanizing bath. The h.c.p. MgZn₂ phase was formed in the Al/Mg-containing Zn-6Al-2Mg and Zn-10Al-5Mg coating layers, forming Zn-Al-MgZn₂ eutectic microstructure. The primary MgZn₂ phase was additionally formed in the Zn-10Al-5Mg coating layers containing high concentrations of Al and Mg. The Vickers hardness values of Zn-0.2Al, Zn-6Al-2Mg, and Zn-10Al-5Mg coating layers were 59.1 ± 1.2 HV, 161.2 ± 5.7 HV, and 215.5 ± 40.3 HV, respectively. The addition of Al and Mg increased the hardness of the coating layer by increasing the fraction of the Al phase (containing Zn) and MgZn₂ intermetallic compound, which were harder than the Zn phase.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.27 no.3
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• pp.321-344
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• 2016

In this study, in order to clarify the unsystematic compilation and publication of books at the Hakbu in the period of Empire of Korea, I aimed to investigate the distinctive features and contents by comparing the record in old literature and with the existing original, and then by analyzing them in the form of bibliography. The summarized findings from this study are as follow; (1) The number of the books compiled/published was 63 types according to the findings until now. (2) It showed that the printing/compiling book in the Hakbu was differently carried out annually. (3) An 84.1% of the published books were printed by using printed edition, and Sinyeon printed edition was classified into 35 types of books, accounted for the most percentage among the printed books. (4) Most of books were bound in type of Thin-cover book using Hanji (Korean paper hand-made from mulberry trees). (5) The price of books was more expensive than that of contemporary books. As time goes by, the price of a book published becomes cheaper. (6) There were 6 types of translated books in the books compiled. As comprehensive study about compiled/published books at the Hakbu, this research will form the base of related research.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1209-1216
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• 2020

In this study, we propose a method for detecting coastal surface wastes using an UAV(Unmanned Aerial Vehicle) remote sensing method and an object detection algorithm based on deep learning. An object detection algorithm based on deep neural networks was proposed to detect coastal debris in aerial images. A deep neural network model was trained with image datasets of three classes: PET, Styrofoam, and plastics. And the detection accuracy of each class was compared with Darknet-53. Through this, it was possible to monitor the wastes landing on the shore by type through unmanned aerial vehicles. In the future, if the method proposed in this study is applied, a complete enumeration of the whole beach will be possible. It is believed that it can contribute to increase the efficiency of the marine environment monitoring field.

• Journal of Powder Materials
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• v.29 no.5
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• pp.382-389
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• 2022

A typical trade-off relationship exists between strength and elongation in face-centered cubic metals. Studies have recently been conducted to enhance strength without ductility reduction through surface-treatment-based ultrasonic nanocrystalline surface modification (UNSM), which creates a gradient microstructure in which grains become smaller from the inside to the surface. The transformation-induced plasticity effect in Fe-Mn alloys results in excellent strength and ductility due to their high work-hardening rate. This rate is achieved through strain-induced martensitic transformation when an alloy is plastically deformed. In this study, Fe-6%Mn powders with different sizes were prepared by high-energy ball milling and sintered through spark plasma sintering to produce Fe-6%Mn samples. A gradient microstructure was obtained by stacking the different-sized powders to achieve similar effects as those derived from UNSM. A compressive test was performed to investigate the mechanical properties, including the yielding behavior. The deformed microstructure was observed through electron backscatter diffraction to determine the effects of gradient plastic deformation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.29-35
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• 2023

This paper makes it possible to search videos based on sentence by improving the previous research which automatically generates rich metadata from videos and searches videos by key words. For search by sentence, morphemes are analyzed for each sentence, keywords are extracted, weights are assigned to each keyword, and some videos are recommended by applying a ranking algorithm developed in the previous research. In order to evaluate performance of video search in this paper, a sufficient amount of videos and sufficient number of user experiences are re required. However, in the current situation where these are insufficient, three indirect evaluation methods were used: evaluation of overall user satisfaction, comparison of recommendation scores and user satisfaction, and evaluation of user satisfaction by video categories. As a result of performance evaluation, it was shown that the rich metadata construction and video recommendation implementation in this paper give users high search satisfaction.

• Clean Technology
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• v.16 no.1
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• pp.19-25
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• 2010

In this work, the conversion of crystalline cellulose into polyols in the presence of hydrogen was examined over noble metal (Pt, Ru, Ir, Rh, and Pd) catalysts supported on activated carbon. For comparison, Pt/${\gamma}-Al_2O_3$ and Pt/H-mordenite were also investigated. Several techniques: $N_2$ physisorption, X-ray diffraction(XRD), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), temperature-programmed reduction with $H_2$ ($H_2$-TPR) and CO chemisorption were employed to characterize the catalysts. The cellulose conversion was not strongly dependent on the types of the catalyst used. Pt/AC showed the highest yields to polyols among activated carbon-supported noble metal catalysts, viz. Pt/AC, Ru/AC, Ir/AC, Rh/AC and Pd/AC.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.53-58
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• 2022

Shape changes of hard mask play a key role in the aspect ratio dependent etch (ARDE). For etch process using high density and energy ions, deformation of hard mask shape becomes more severe, and high aspect ratio (HAR) etch profile is distorted. In this study, polygonal geometric model for shape-deformation of amorphous carbon layered hard mask is suggested to control etch profile during the process. Mask shape is modeled with polygonal geometry consisting of trapezoids and rectangles, and it provides dynamic information about angles of facets and etched width and height of remained mask shape, providing important features for real-time HAR etch profiling.

• 대학교육
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• s.96
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• pp.62-73
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• 1998

효율적인 학부제 운영을 위해서는 학생들의 전공지도를 철저히 하고, 제한된 교육여건을 감안하여 전공학생수의 상한선을 두며, 기초학문 전공자에게 장학금 지급을 확대하고, 학부 1, 2학년에게는 기초학문 과목만 개설한다. 또한 기초-응용학문의 연계전공을 우선적으로 개발하고, 응용학문 분야의 대학원생 선발 시 동계 진학률을 제한하여 타전공자, 특히 기초학문 전공자에게 문호를 개방함으로써 기초-응용학문의 조화로운 발전을 꾀한다.

• Proceedings of the Korea Society of Design Studies Conference
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• 1999.10a
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• pp.2-3
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• 1999

1999년 현재 한국의 대학교는 종전의 학과 단위의 운영에서 학부제로의 통합운영 방식으로 전환하고 있으며 이네 학부제 편성을 마친 학교와 이를 진행 또는 계획중인 학교가 상당수이다. (중략)