• 대한지역사회영양학회지
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• 제15권5호
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• pp.656-669
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• 2010

Rapid shift to western dietary patterns and social drive of thinness would lead to increase the likelihood of developing eating disorders. This study was performed to analyze the associated factors between dietary pattern and self visualization in terms of body shape, which may increase the risk of disturbed eating attitudes among high school students in Korea. A cross-sectional study was conducted from 2009 to 2010 for high school students including both male and female students, from 6 schools in Gyunggi Province, Korea. A total of 766 students self-reported a questionnaire, including weight control practice, perceptions of self body image and ideal body image, dietary habit, and EAT-26 (Eating Attitude Test-26). Logistic regression analysis was used to fine the factors potentially associated with disturbed eating attitudes. Statistical analysis was conducted using SAS program (version 9.1). Results showed that disturbed eating attitudes were found in 8.7% of male high school students, and in 20.8% of female high school students. Experience of body weight control was reported by 56.2% of male students and by 87.3% of female students. According to multiple logistic regression analysis, obesity was independently associated with high risk of disturbed eating attitudes in male students [Odds Ratios (OR) 2.96, 95% Confidence Interval (CI) 0.90-9.71]. Body image dissatisfaction (OR 2.77, 95%CI 1.37-5.62) and extended family type (OR 2.70, 95%CI 1.05-6.90) were independently associated with high risk of disturbed eating attitudes, especially in female students. In conclusion, proper efforts in education for obesity and developing self-esteem to reduce the risks of disturbed eating attitudes should be implemented in high school nutrition program.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.38-43
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• 2008

The hydroforming technology has been spreaded dramatically in automotive industry last 10 years. Itmay cause many advantages to automotive applications in terms of better structural integrity of the parts, lower cost from fewer part count, material saving, weight reduction, lower springback, improved strength and durability and design flexibility. In this study, the whole process of rear sub-frame parts development by tube hydroforming using steel material having tensile strength of 440MPa grade is presented. At the part design stage, it requires feasibility study and process design aided by CAE (Computer Aided Design) to confirm hydroformability in details. Effects of parameters such as internal pressure, axial feeding and geometry shape in automotive rear sub-frame by hydroforming process were carefully investigated. Overall possibility of hydroformable sub-frame parts could be examined by cross sectional analyses. Moreover, it is essential to ensure the formability of tube material on every forming step such as pre-bending, preforming and hydroforming. In addition, all the components of prototyping tool are designed and interference with press is examined from the point of geometry and thinning.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.50-50
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• 2000

In this paper, a new measuring system is :proposed which can measure the fine 6-DOF displacement of rigid bodies. Its measurement principle is based on detection of laser beam reflected from a specially fabricated mirror that looks like a triangular pyramid having an equilateral cross-sectional shape. The mirror has three lateral reflective surfaces inclined 45$^{\circ}$ to its bottom surface. We call this mirror 3-facet mirror. The 3-facet mirror is mounted on the object whose 6-DOF displacement is to be measured. The measurement is operated by a laser-based optical system composed of a 3-facet mirror, a laser source, three position-sensitive detectors(PSD). In the sensor system, three PSDs are located at three corner points of a triangular formation, which is an equilateral triangular formation tying parallel to the reference plane. The sensitive areas of three PSDs are oriented toward the center point of the triangular formation. The object whose 6-DOF displacement is to be measured is situated at the center with the 3-facet mirror on its top surface. A laser beam is emitted from the laser source located at the upright position and vertically incident on the top of the 3-fatcet mirror. Since each reflective facet faces toward each PSD, the laser beam is reflected at the 3-facet mirror and splits into three sub-beams, each of which is reflected from the three facets and finally arrives at three PSDs, respectively. Since each PSD is a 2-dimensional sensor, we can acquire the information on the 6-DOF displacement of the 3-facet mirror. From this principle, we can get 6-DOF displacement of any object simply by mounting the 3-facet mirror on the object. In this paper, we model the relationship between the 6-DOF displacement of the object and the outputs of three PSDs. And, a series of simulations are performed to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects.

• Restorative Dentistry and Endodontics
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• 제28권1호
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• pp.41-49
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• 2003

There are increasing usage of Nickel-Titanium rotary files in modern clinical endodontic treatment because it is effective and faster than hand filing due to reduced step. This study was conducted to evaluate the effect of canal preparations using 3 different rotary Nickel-Titanium files that has different cross sectional shape and taper on the maintenance of canal curvature. Simulated resin block were instrumented with Profile(Dentsply, USA), GT rotary files(Dentsply, USA), Hero 642(Micro-Mega France), and Pro-Taper(Dentsply, USA). The image of Pre-instrumentation and Post-instrumentation were acquired using digital camera and overspreaded in the computer. Then the total differences of canal diameter, deviation at the outer portion of curvature, deviation at the inner portion of curvature, movement of center of the canal and the centering ratio at the pre-determined level from the apex were measured. Results were statistically analyzed by means of ANOVA, followed by Scheffe test at a significance level of 0.05. The results were as follows； 1. Deviation at the outer portion of curvature, deviation at the inner portion of curvature were showed largest in Pro-Taper so also did in the total differences of canal diameter(p＜0.05). 2. All the groups showed movements of center Profile combined with GT rotary files and Hero 642 has no difference but Pro-Taper showed the most deviation(p＜0.05). 3. At the 1, 2, 3mm level from the apex movements of center directed toward the outer portion of curvature, but in 4, 5 mm level directed toward the inner portion of curvature(p＜0.05). As a results of this study, it could be concluded that combined use of other Nickel-Titanium rotary files is strongly recommended when use Pro-Taper file because it could be remove too much canal structure and also made more deviation of canal curvature than others.

• Journal of Nutrition and Health
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• 제46권6호
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• pp.552-559
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• 2013

This study is conducted in order to investigate the prevalence of vitamin mineral (VM) supplement use and its related factors among Korean adolescents. Using a cross-sectional study design, information was obtained by questionnaires from adolescents selected by stratified sampling in large, small and middle-size cities, as well as rural areas of the whole country, followed by convenience sampling. The total number of participants in this study was 1,407 adolescents ($15.2{\pm}1.6$ years) attending middle or high schools, chosen from various cities and rural areas in Korea. The prevalence of VM supplement use was 65.5%, and there was no significant difference between the genders. City dwellers took VM supplements more frequently than those adolescents from rural areas (p < 0.01). The VM supplement users tended to have higher family income, parents' academic background, and socioeconomic status, respectively (p < 0.001). The greater part of VM supplement users replied that they acquired their nutritional information from their parents, relatives and friends, while many nonusers replied that they did it from school classes (p < 0.05). Compared to nonusers, VM supplement users had greater 'self concern about health' (p < 0.05), 'parents' concern about child's health, growth, and nutritional intake' (p < 0.001), and 'parents' concern about child's grade point' (p < 0.01). However, there was no significant difference between users and nonusers when it came to 'self perception of body shape' or 'BMI'. In addition, users significantly had greater nutritional beliefs concerning VM supplements than nonusers (p < 0.001). These results showed that VM supplement use has been common among adolescents in Korea, and supplement use of subjects has been related with various factors. Among them, it was shown that especially parents great influence the use of VM supplements by adolescents. Thus, not only education for adolescents, but also that for parents is needed to help adolescents take VM supplements properly.

• 한국분무공학회지
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• 제25권1호
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• pp.8-14
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• 2020

Recently, 1-D model-based engine development using virtual engine system is getting more attention than experimental-based engine development due to the advantages in time and cost. Injection rate profile is the one of the main parameters that determine the start and end of combustion. Therefore, it is essential to set up a sophisticated model to accurately predict the injection rate as starting point of virtual engine system. In this research, procedure of 1-D model setup based on AMESim is introduced to predict the dynamic behavior and injection rate of diesel injector. As a first step, detailed 3D cross-sectional drawing of the injector was achieved, which can be done with help of precision measurement system. Then an approximate AMESim model was provided based on the 3D drawing, which is composed of three part such as solenoid part, control chamber part and needle and nozzle orifice part. However, validation results in terms of total injection quantity showed some errors over the acceptable level. Therefore, experimental work including needle movement visualization, solenoid part analysis and flow characteristics of injector part was performed together to provide more accuracy of 1-D model. Finally, 1-D model with the accuracy of less than 10% of error compared with experimental result in terms of injection quantity and injection rate shape under normal temperature and single injection condition was established. Further work considering fuel temperature and multiple injection will be performed.

• 대한기계학회논문집A
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• 제29권10호
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• pp.1289-1297
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• 2005

The flow in a microchannel is usually characterized as a low Reynolds number (Re) so that good mixing is quite difficult to be achieved. In this regard, we developed a novel chaotic micromixer, named Serpentine Laminating Micromixer (SLM) in the present study, Part 1. In the SLM, the higher level of chaotic mixing can be achieved by combining two general chaotic mixing mechanisms: splitting/recombination and chaotic advection. The splitting and recombination (in other term, lamination) mechanism is obtained by the successive arrangement of 'F'-shape mixing units in two layers. The chaotic advection is induced by the overall three-dimensional serpentine path of the microchannel. Chaotic mixing performance of the SLM was fully characterized numerically. To compare the mixing performance, a T-type micromixer which has the same width, height and length of the SLM was also designed. The three-dimensional numerical mixing simulations show the superiority of the SLM over the T-type micromixer. From the cross-sectional simulation results of mixing patterns, the chaotic advection effect from the serpentine channel path design acts favorably to realize the ideal lamination of fluid flow as Re increases. Chaotic mixing mechanism, proposed in this study, could be easily integrated in Micro-Total-Analysis-System, Lab-on-a-Chip and so on.

• 콘크리트학회논문집
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• 제23권6호
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• pp.781-790
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• 2011

이 연구는 다양한 보강상세를 갖는 CFRP(carbon fiber reinforced polymer)로 표면매립 보강된 철근콘크리트보의 보강효과에 관한 실험연구이다. 다양한 보강상세를 갖는 표면매립공법의 보강효과를 분석하기 위해 실험변수로 CFRP 보강재의 단면형상, 보강량, 매립 개수 및 위치 등의 다양한 보강상세를 적용하여 총 14개의 실험체를 제작하였다. 실험 결과, 표면매립보강의 파괴모드는 보강재 단면형상에 상관없이 보강재와 충전재가 하나로 거동하는 부착파괴 및 보강재 파단을 보였고, 홈 간격에 따라 홈 주변 콘크리트의 파괴면이 중첩되어 조기 부착파괴가 발생하는 것으로 나타났다. 등가 단면을 고려하여 부착상세를 개선한 기계적 맞물림(MI) 실험체의 파괴모드는 기존 부착파괴에서 CFRP 보강재 파단으로 개선되었고, CFRP 효율은 83%에서 100%로 향상되었다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제17권3호
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• pp.231-238
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• 1995

The scapular flap, described by dos Santos in 1986, has been used successfully for the reconstruction of a variety of defects of oro-mandible. Some have defined the gross and vascular anatomy of the lateral border of the scapula, yet useful anatomical information and a complete description of area and contour of each cut surface of lateral border of scapula, which is very important for esthetic and functional reconstruction using dental implants, are missing. These prompted us to clarify the cross-sectional area of lateral border of scapula. Twenty three scapulas of 15 fixed adult Caucasian cadavers were sectioned in every 1cm interval along the lateral border of scapular, and the metric relations and the shape of cut surface were assessed. The lateral border of the scapula, consisting of cortico-cancellous bone measuring $7.86{\pm}0.97mm$ in width, $19.6{\pm}2.86mm$ in height and $12{\pm}1.78cm$ in length, could be harvested as an osteocutaneous scapular flap or as a single vascularized bone flap. The mean thickness of cortical bone of lateral, medial, dorsal and costal surface was $0.46{\pm}1.48mm$, $1.78{\pm}1.34mm$, $1.54{\pm}1.11mm\;and\;1.35{\pm}0.87mm$, respectively. So we have thought that all scapular transplants could be supported osseointegrated implants for fixation of dental prosthesis.

• 농업과학연구
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• 제22권1호
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• pp.11-23
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• 1995

The CAD/CAM system for the manufacturing automation is the newest technology in mechanical engineering area and becomes the important research subject nowadays. Most of all hardwares and softwares for the CAD/CAM system used in the our manufacturing companies such as automobile company are developed by the foreign country and the purchasing price of them is very expensive but their applicability to a certain area is very limited. This study was conducted to develope a CAD/CAM system for the design and the automatic manufacturing of the iron pattern shaped with 3 - dimensional free curved surface, and to test its applicability to the design and the manufacturing of the rotary blade. The results obtained from the study are as follow; 1. The CAD system which can process graphic procedures from the free curved surface shaped data was developed with personal computer. 2. The CAM main program was developed. This main program could produce CL data from CAD data file by checking the tool interference according to the cutting mode. 3. The sub. program which can simulate the tool trace from the CL data was developed. 4. The post processor for the Deckel FP2NC NC milling machine from CL data file was developed and the sub program could transmit NC program through modem to NC milling machine was developed. 5. The developed CAM system seemed to be applicable to any other system. Because the measuring results of the cross sectional thickness of the plastic model from the manufacturing iron pattern by the system showed that this system could properly check the tool interference. 6. In took 75~90 hours to manufacture two iron patterns of rotary blade. For the sake of convenience in applying to the other systems, this system was developed in BASIC and FORTRAN computer language and minimum portion of machine language as possible.