• 한국식품저장유통학회지
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• 제8권2호
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• pp.217-223
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• 2001

The antimicrobial and glucosyltransferase(GTase) inhibition activity were searched for 30 species of various folk drugs and by products of food industry. Among them, two species, gallnut and red grape husk water extracts, were selected for the powerful antimicrobial and GTase inhibition activity. The polyphenol fractions of gallnut and red grape husk were showed very greater antimicrobial activity on both Gram(+) and (-), B. subtilis and E. coli. The minimum antimicrobial activity of gallnut polyphenol fraction were 1.0mg for B. subtilis and 3,0mg for E. coli. Red grape husk was 2.0mg for B. subtilis and 3.0mg for E coli. The polyphenol fractions of gall nut and red grape husk were showed powerful GTase inhibition activity. The concentrations of these fractions for 80% inhibition of GTase activity were 1.08$\times$10$\^$-3/mg/㎖ and 1.08$\times$10$\^$-2/mg/㎖, respectively. The most abundant compound in these fraction seems to be polyphenol derivatives. From these results, we think that the gallnut and the red grape husk polyphenol fraction had more antimicrobial and anti-plaque activities than artificial synthetic preservatives as an economic point of view.

• 한국식생활문화학회지
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• 제18권3호
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• pp.292-301
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• 2003

The purpose of this study was to know the perception on acne for the college students to provide basic data for the suitable care of acne. Self-administrated questionnaires were completed by 641 college students. Dietary attitude, food habit, general perceptions on acne, knowledge level on acne, and relationship perception between special food and acne were analyzed. The results were as follows. 1. Self reported health status, smoking, obesity index were significantly different by experience of acne. 2. Dietary attitude and food habits were not significantly different by experience of acne. 3. Acne experienced subjects had acne on their face mostly and responded positively to specialized treatment. Proportions of getting the knowledge on acne were 40.6% from friends, 35.4% from magazine and 21.7% from TV or radio. 4. Proportions of correctly answered for the questions about pregnancy, hair cosmetics, oily food, male hormone, family history, constipation related with acne were less than 50% for acne experienced subjects. 92.5% of acne experienced subjects were answered eating chocolate, nut, and fat were related with breaking out and aggravating of acne. Perceptions on breaking out factors and aggravating factors of acne were not significantly different by gender. 5. More than 70% acne experienced subjects stated that instant foods, oily foods, meats, cookies, nuts were related with developing and aggravating acne. Soybean, Seaweed, fermented fish were recognized as less related with developing and aggravating acne.

• 한국식품과학회지
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• 제20권6호
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• pp.868-872
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• 1988

잣을 저장조건을 달리하여 산화양상을 살펴보고 이어 정제단계별로 산화양상에 따른 변화를 살펴보았다. 잣을 $35^{\circ}C$에서 10주간 저장하면서 함유지방질의 산화양상을 살펴본 결과 잣 알갱이 상태는 조직을 마쇄하더라도 지방질로 추출한 상태보다 대단히 높은 산화안정성을 나타내었다. 또한 조지방질은 정제단계를 거칠수록 그 산화안정성이 감소되었으며 정제지방질, 탈검 및 탈산된 지방질, 탈검 탈산 및 탈색된 지방질, 탈검된 지방질, 조지방질 순으로 산화 안정성이 높아졌다. 이것은 정제단계에서 제거된 물질들이 산화 안정성을 증가시키는 요인으로 작용하는 것으로 여겨진다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1363-1366
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• 2005

The tiebar is used by joint for keeping from deformation by conserving tensile load between two structure. The tiebar, bolt joining type, is combined by tiebar and clevis like bolt and nut. By coupled, it maintains tensile load. While it goes through repeated load, it occurs to loose because joining force between clevis and nuts is reduced. So, continuos maintenance is needed such as making tighter periodically, repairing the broken part and so on. For that reason, this paper calculates necessary torque unfastening joint for conventional tiebar and presenting tiebar theoretically and then consider the reason that conventional bolt-typed tiebar unties. Also, through vibration untied test for two types of tiebar we confirm that presenting tiebar have a improvement of unfastening when we compare with the conventional one.

• 한국정밀공학회지
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• 제18권6호
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• pp.133-140
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• 2001

This paper suggests another system for a cutting force measuring tool in a milling process. Generally, tool dynamometer is taken into account for the most appropriate cutting force measuring tool in the analysis of cutting mechanism. However, high price and limited space make it difficult to be in-situ system for controllable milling process. Although an alternative method using AC current of servo-motor has been suggested, it is unsuitable for cutting force control because of small upper frequency limit and noise. The cutting force measuring system is composed of two load cells placed between the moving table bracket and the nut flange part of ballscrew. It has many advantages such as low cost and wide range measurement than tool dynamometer because of the built-in moving table and the low cost load cell. The static and dynamic model of the measuring system using imbeded load cell is introduced. Various Experiments are carried out to validate both models. By comparing the cutting forces from a series of end milling experiments on the tool dynamometer and the system developed in this paper, the accuracy of the cutting force measuring system is verified. Upper frequency limit is measured by the experiment of dynamic characteristics.

• 제어로봇시스템학회논문지
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• 제15권11호
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• pp.1108-1114
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• 2009

Mobility is one of the most important features for a guard robot since it should be operated in rough places. A wheel-based mobile robot capable of jumping is an appropriate structure for a guard robot because it can easily satisfy the requirements for small guard robots. The jumping robot can reach a higher place more rapidly than other locomotion methods. This research proposes a small robot equipped with the jumping mechanism based on the conical spring with the variable length endtip. The variable length endtip enables the independent control of the jump force and jump angle which are related to the jump height and jump distance, respectively. Various experiments demonstrated that the proposed jumping mechanism can provide the independent control of jump force and jump angle, and improve the mobility of a small robot to overcome an obstacle. Furthermore, a combination of the jumping mechanism and the PSD sensor to measure the distance to the step enable the jumping robot to autonomously climb stairs.

• 동력기계공학회지
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• 제15권4호
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• pp.37-41
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• 2011

This paper introduces the special eddy current sensor and its characteristic for bolt hole defect evaluation in gas turbine rotor. In the past, Fluorescent penetration inspection method was used for qualitative defect evaluation in gas turbine rotor bolt hole. This method can defect the bolt hole defect but can not evaluate the defect size. Nowadays, eddy current method is used quantitative defect evaluation due to advanced sensor design technology. And eddy current method is more time and cost saving than the old method. We developed bolt shape eddy current sensor for the rotor bolt hole defect detection and evaluation. The eddy current sensor moves to the bolt hole guided by screw nut and detects the defect on the bolt hole. The bolt hole mock-up and artificial defects were made and used for the signal detection & resolution analysis of eddy current sensor. The results show that signal detection capability is enough to detect 0.2 mm depth defect. And the resolution capability is enough to differentiate 02, 0.5, 1.0 and 2.0 mm depth defect.

• 동력기계공학회지
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• 제15권4호
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• pp.19-24
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• 2011

The operational efficiency of domestic gas turbine is about 25% and it is now in the trend of the gradual growth in spite of the severe temperature, frequent starting and shutdown according to the environmental management and the energy-efficient use. Rotor bolts of gas turbine in power plants have been the cause of defects because these gas turbines have been operated for a long time under the high pressure and temperature environment experiencing the aging change and stress concentration of the bonded part. The connection parts of the bolt revealed various failure shape and these parts were elongated under very low pressure when operated in the relaxed condition. The cause is in the lack of the metal distribution in the bottle lack area and the cap screw of the bolt is broken totally in case that the nut is fastened in most cases. Gas turbine rotor bolts are connected to the rotor wheel and these bolts caused the vibration, the bulk accident of the rotor in the event that the coupling power among these bolts was relaxed. Therefore, we would like to evaluate the soundness of the main part of the gas turbine rotor bolt through the measurement of the inner condition change along with the mechanic deterioration and temperature, stress in the gas turbine rotor material.

• 대한기계학회논문집A
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• 제27권1호
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• pp.18-25
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• 2003

A haptic hand controller (HHC) operated by the user’s hand can receive information on position and orientation of the hand and display force and moment generated in the virtual environment to the hand. In this paper, a 3-DOF hand controller is first presented, in which all the actuators are mounted on the fixed base by combining a 5-bar linkage and a gimbal mechanism. The 6-DOF HHC is then designed by connecting these two 3-DOF devices through a handle which consists of a screw and nut. Analysis using performance index is carried out to determine the dimensions of the device. The HHC control system consists of the high-level controller for kinematic and static analysis and the low-level controller for position sensing and motor control. The HHC used as a user interface to control the mobile robot in the virtual environment is given as a simple application.

• 한국정밀공학회지
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• 제16권2호통권95호
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• pp.218-224
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• 1999

In the feed drive systems of machine tools that consist of many mechanical components such as motor, coupling, ballscrew, nut or table, a torsional vibration is often generated because of its elastic elements in torque transmission. Generally, the accuracy of motion control system is strongly influenced by the dynamic behavior of coupled transmission components. Especially, a torsional vibration caused by the elasticity of mechanical elements might deteriorate the quick movement of system and lead to shorten the life time of the mechanical transmission elements. So, it is necessary to analyze the electromechanical system mathematically to optimize the dynamic characteristics of the feed system. In this paper, the mathematical model of a feed drive system was developed and its mechanical characteristics were analyzed on the basis of the proposed model. The design concepts of speed control loop to stabilize a feed drive system were also proposed.