• 한국인터넷방송통신학회논문지
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• 제17권2호
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• pp.257-262
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• 2017

본 논문에서는 이중 슬리브를 갖는 직사각형 평면 모노폴 안테나에 하프 커팅과 불연속 급전 구조를 적용하여 안테나 특성을 확인하였다. 이중 슬리브를 갖는 직사각형 평면 모노폴 안테나를 자기 대칭 라인을 중심으로 하프커팅을 하고, 급전부에 불연속 구조를 적용과 이중 슬리브 간격을 조정하여 임피던스 매칭을 하였다. 안테나 파라미터 특성을 확인하기 위하여 ANSYS사의 HFSS 시뮬레이터를 이용하였고, 안테나 크기는 $21{\times}40mm^2$이다. 제안한 안테나에서 VSWR이 2 이하인 시뮬레이션 주파수 대역은 2.6GHz~10.25GHz이다. 주파수 대역폭은 7.65GHz이다. 실제로 제작한 안테나의 주파수 대역은 3.3GHz~9.75GHz이며, 주파수 대역폭은 6.45GHz이다. 측정된 복사패턴 주파수는 3.5GHz, 5.5GHz, 7.5GHz, 9.5GHz이다. 모든 주파수에서 다이폴안테나 패턴과 유사한 복사패턴 결과를 얻을 수 있었다.

• KSBB Journal
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• 제31권1호
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• pp.20-26
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• 2016

This study aims to examine the optimum blanching conditions as a pretreatment condition to improve the storage stability of Dolsan leaf mustard pickle. The effects of the blan- ching temperature and time were investigated at a temperature range of $80-100^{\circ}C$. Sampling was done for 1 month after a 5 days interval. The L value of the Dolsan leaf mustard was found to be the highest at $80^{\circ}C$. The cutting force increased as the blanching temperature increased. The tensile strength decreased at $95^{\circ}C$ and $100^{\circ}C$. In addition, the sensory evaluation scores were the best at $80^{\circ}C$. The storage stability was assessed at various blanching temperatures to increase the sinigrin content during storage. Liquid chromatography with photodiode array and tandem mass spectrometry (LC-PDA/MS/MS) analysis was conducted to identify and quantify the sinigrin content in the Dolsan leaf mustard. Sinigrin as an internal standard was co-injected into each sample solution. The sample was monitored by recording the ultraviolet absorbance at 228 nm and by electrospray ionization (ESI) positive ion mode in the m/z 50-1,500 range. Blanching the sample at $80^{\circ}C$ showed the highest sinigrin concentration during storage among various temperatures and the maximum concentration was 350 ppm at 15 days storage. Study on utilization of vegetable from food processing of leaf mustard and preservation conservation results suggest that blanching at $80^{\circ}C$ is expected to improve the palatability of the pickle.

• 한국운동역학회지
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• 제26권4호
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• pp.433-441
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• 2016

Objective: The purpose of this study was to understand the injury mechanism and to provide quantitative data to use in prevention or posture correction training by conducting kinematic and kinetic analyses of risk factors of lower extremity joint injury depending on the change of direction at different angles after a landing motion. Method: This study included 11 men in their twenties (age: $24.6{\pm}1.7years$, height: $176.6{\pm}4.4cm$, weight: $71.3{\pm}8.0kg$) who were right-leg dominant. By using seven infrared cameras (Oqus 300, Qualisys, Sweden), one force platform (AMTI, USA), and an accelerometer (Noraxon, USA), single-leg drop landing was performed at a height of 30 cm. The joint range of motion (ROM) of the lower extremity, peak joint moment, peak joint power, peak vertical ground reaction force (GRF), and peak vertical acceleration were measured. For statistical analysis, one-way repeated-measures analysis of variance was conducted at a significance level of ${\alpha}$ <.05. Results: Ankle and knee joint ROM in the sagittal plane significantly differed, respectively (F = 3.145, p = .024; F = 14.183, p = .000), depending on the change of direction. However, no significant differences were observed in the ROM of ankle and knee joint in the transverse plane. Significant differences in peak joint moment were also observed but no statistically significant differences were found in negative joint power between the conditions. Peak vertical GRF was high in landing (LAD) and after landing, left $45^{\circ}$ cutting (LLC), with a significant difference (F = 9.363, p = .000). The peak vertical acceleration was relatively high in LAD and LLC compared with other conditions, but the difference was not significant. Conclusion: We conclude that moving in the left direction may expose athletes to greater injury risk in terms of joint kinetics than moving in the right direction. However, further investigation of joint injury mechanisms in sports would be required to confirm these findings.

• 자원환경지질
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• 제13권2호
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• pp.104-116
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• 1980

The Ulsan mine is one of the largest contact metasomatic magnetite and scheelite deposits in the southeastern part of Korea. Mineralization at the Ulsan mine is localized along the contact between upper Cretaceous volcanic rocks and age unknown limestone which were intruded by 58 m.y. -old biotite-horndlende granite. General zonal sequence of skarn toward crystalline limestone from limestone-volcanics contact is grandite, grandite-salite and salite zones. On the otherhand volcanics origin skarns exhibits zonal sequences toward hornfels from boundary with limestone is garnet, garnet-epidote, and epidote zone. Compositions of garnets and clinopyro xenes are determined by the X-ray diffraction and reflective indecies. Local brecciation of these early skarns were followed by formation of the later skarn as zoned patches, breccia fillings and cross-cutting veins. Paragenetic sequence of late skarn minerals which is exhibited in the zoned patches and veins is an overlapping progression with time from andradite through hedenbergite or actinolite, quartz to calcite deposition. Magnetite metallization followed early formed skarns and pyrite pyrrhoite, sphalerite, galena, tennantite, scheelite and arsenopyrite deposition were simultaneously with hedenbergite, quartz and calcite of late skarn. Filling temperatures of fluid inclusions in calcites range from $160^{\circ}$ to $280^{\circ}C$.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 국제학술대회
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• pp.373-377
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• 2005

The work of hairdressers includes washing, coloring, bleaching, permanent waving, conditioning, and cutting hair. Hairdressers are subjected to a number of physical and toxicological hazards. The toxicological hazards are those resulting from exposure to a wide range of chemicals and from chemicals are usually classified active processes. In this study, twenty beauty shops were selected to assess the exposure to indoor air pollutants such as VOCS and particulate matter($PM_{10}$) during one month from September 1 to September 30, 2003. Indoor air quality of beauty shops might be worse by vehicle emissions because the beauty shops were generally located near roadways. Personal exposures to VOCs and PM lo were related to indoor concentrations of beauty shops. According to the questionnaire, hairdressers complained of sore throat, eye irritation, and nervousness as physical symptoms. Conclusively, customers as well as workers in the beauty shops might be highly exposed to air pollutants from indoor sources and outdoor sources. Therefore, proper management methods should be taken to improve the indoor air quality in beauty shops.

• 대한기계학회논문집
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• 제19권1호
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• pp.22-37
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• 1995

Industrial robot has played a central role in the production automation such as welding, assembling, and painting. There has been, however, little effort to the application of robots in machining work(grinding, cutting, milling, etc.) which is typical 3D work. The machining automation requires a high stiffness robot arm to reduce deformation and vibration. Conventional articulated robots have serially connecting links from the base to the gripper. So, they have very weak structure for he machining work. Stewart Platform is a typical parallel robotic mechanism with a very high stiffness but it has a small work space and a large installation space. This research proposes a new machining robot arm with a double parallel mechanism. It is composed of two platforms and a central axis. The central axis will connect the motions between the first and the second platforms. Therefore, the robot has a large range of work space as well as a high stiffness. This paper will introduce the machining work using the robot and design the proposed robot arm.

• 한국생산제조학회지
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• 제19권5호
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• pp.672-677
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• 2010

The goal of this study is to simplify the measurement process of the flat zone length produced by a flexible disk grinding system for the process automation. The image of workpiece in the grinding process is obtained, and the cutting speed and the feeding speed are controlled carefully to maximize the flat zone length. The gradient, the inflection point and the length of the line in the image are calculated, and the length is also measured by using a projector. Processing conditions and inversely proportional to flat zone length was changing. The flat zone length is estimated by Neural network algorithm considering the process conditions with the estimated error range as 0.06~3.61%, the Neural network algorithm for the grinding process estimation is found to be useful for building the process automation database.

• Tribology and Lubricants
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• 제34권4호
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• pp.132-137
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• 2018

Ultrasonic waves are used in various applications in multiple devices, sensors, and high-power machinery, such as processing machines, welders, and cleaners, because the acoustic vibration frequencies are above the human audible frequency range. In ultrasonic machining, electrical energy at a high frequency of 20 kHz or more is converted into mechanical vibration by a vibrator and an amplifier. This technique allows instantaneous separation between a tool and a workpiece during machining, machining by pulse impulse force at the time of re-contact and minimizes the minute elastic deformations of the workpiece and machine tools due to the cutting effect. The Al7075 alloy used in this study is a typical aluminum alloy with superior strength that is mainly used in aircrafts, automobiles, and sporting goods. To investigate the optimal conditions for machining aluminum alloy using ultrasonic vibration, the present experiment utilized the Taguchi orthogonal array method, and the coefficient of friction was analyzed using the characteristics of the Taguchi technique. In ultrasonic friction and abrasion tests, the changes in the friction coefficient were measured in the absence of ultrasonic vibrations and at 28 kHz and 40 kHz. As a result, the most considerable influence on the friction coefficient was found to be the normal load, and the frequency of ultrasonic vibrations increases, the coefficient of friction increases. It was thus confirmed that the amount of wear increases when ultrasonic vibration is applied.

• Journal of Nutrition and Health
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• 제37권6호
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• pp.493-501
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• 2004

The purpose of this study was to evaluate weight control program provided by university health care center for female college students. The program was 8-week long and composed of diet, exercise, and behavioral modification. Evaluation was made on the completion of 8-week program and a follow-up survey was done at 3-24 months after the end of program by telephone or bye-mail. Total of 76 women completed the 8-week program and 51 for follow-up survey. On the completion of 8-week program, significant decreases in body weight, BMI, body fat (kg), ％ body fat, and WHR were resulted, however, no change in muscle mass was found. Even the subjects without weight change showed significant reduction in body fat (kg) and ％ body fat. Total food intake was decreased resulting in reduced intakes of most nutrients. Meal distribution of energy was changed; ％energy from snack decreased from 22％ to 14％, and proportion for breakfast increased. Blood values of hemoglobin, hematocrit, total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglyceride were within normal range, and no changes were observed by this program. The follow-up survey revealed that 88.3％ of the subjects continued to lose weight after completion of the program, while only 7.8％ gained weight. And 78.4％ of the subjects considered the program effective. In conclusion, the weight reducing regime with education is effective for long lasting weight control and health conscious behavior for female college student. Since the subjects reduced the size of meal, instead of cutting only calories down, food selection to meet all the nutrient requirements except energy should be emphasized.

• Interaction and multiscale mechanics
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• 제5권4호
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• pp.399-405
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• 2012

A dissipative particle dynamics (DPD) simulation was presented to analyze surface wettability and contact angles of a droplet on a solid platform. The many-body DPD, capable of modeling vapor-liquid coexistence, was used to resolve the vapor-liquid interface of a droplet. We found a constant density inside a droplet with a transition along the droplet boundary where the density decreased rapidly. The contact angle of a droplet was extracted from the isosurfaces of the density generated by the marching cube and a spline interpolation of 2D cutting planes of the isosurfaces. A wide range of contact angles from $55^{\circ}$ to $165^{\circ}$ predicted by the normalized parameter ($|A_{SL}|/B_{SL}$) were reported. Droplet with the parameters $|A_{SL}|&gt;5.84B{_{SL}}^{0.297}$ was found to be hydrophilic. If $|A_{SL}|$ was much smaller than $5.84B{_{SL}}^{0.297}$, the droplet was found to be superhydrophobic.