• International Journal of Computer Science & Network Security
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• 제23권3호
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• pp.193-202
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• 2023

Numerous articles under the study and the examination of heavy metals in human teeth have been published in recent years. The heavy metal poisoning is a widespread issue emerged in toxicology area these days. It has been discovered that long-term exposure to heavy metals typically present in traces, in our everyday meals, drinking water, and in the environment as pollution causes heavy metal poisoning in human beings. Industrial effluents, Coal and Oil, as well as a variety of consumer items, such as cosmetics, can all cause this type of exposure. Teeth, which are often thought of as exoskeleton parts, store heavy metals with a high affinity and represent long-term exposure information. In this study, we have chosen and examined the sections of dentine instead, then examined the entire tooth. We have combined the work done on the examination of heavy metals in human teeth using several instrumental approaches e.g. "Optical Spectroscopic Techniques" to detect elemental profile of human teeth in the current study.

• 대한기계학회논문집A
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• 제21권11호
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• pp.1827-1836
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• 1997

In this paper, the clamping type forging of helical gears has been investigated. Clamping type forging is an operation in which the product is constrained to extrude sideways through an orifice in the container wall. Punch is cylindrical shaped. The punch compresses a cylindrical bilet placed in a die insetr. As a consequence the material flows in a direction perpendicular to that of punch movement. The forging has been analysed by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, an involute curve has been introduce to re4present tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, helix angle, friction factor and initial height of billet on the forging of helical gears. Some firgiing experiments were catrried out with aluminium alloy to show the validity of the analysis. Good agreement was found between the predicted values of the forging load and obtained from the experimental results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.152-155
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• 2002

An industrial robot noise has various noise sources such as gears, motors, bearings, and controller fans. Among these, gears are the most dominant source for noise. The gear noise, caused by tooth profile, elastic deformation, machining error and wear, is directly correlated with the transmission error of mating gear. Due to the fact that has several axis and many gears, it is difficult to understand the characteristics of the vibration and noise of robots. In this study, some advanced analysis techniques based on digital signal processing such as power spectrum, time spectral map, RPM map, and etc., were applied for locating the dominant frequency components of the robot noises and identifying their sources. In addition, sound quality analysis was performed in order to evaluate the operator's annoyance. The noise and vibration measurements were carried out at several points during the operation of each axis considering the effect of load and posture of the robot. Eased on the results, proper countermeasures to reduce excessive noise level have been suggested considering the characteristics of sources.

• International journal of advanced smart convergence
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• 제9권3호
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• pp.199-206
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• 2020

A wheelchair is an essential rehabilitation assistant device for the movement of paraplegia patients and generally paralyzed patients who cannot walk normally. In particular, the applicability of the manual/motorized wheelchair is gradually increasing. Until now, decelerators using belt, chain and worm gears, etc have been widely used. However, a decelerator takes a large space although it is a simple device and thus is not ideal for the driving part of manual/motorized wheelchair. For these reasons, in this study we developed a driving part producing a large driving force through a decelerator using planetary gears rather than conventional worm gear-based decelerator. We designed the tooth profile of the planetary gears for decelerator using Kisssoft program, In addition, we designed the driving part so as to apply it to the wheels of conventional wheelchairs, and then optimized the mechanism for the principles of manual/motorized transposition of the driving part and the operational principles. Based on the results of this study, we finally designed and manufactured a driving part for wheelchair decelerator in the form of planetary gears with 1 sun gear, 2 planetary gears and 1 ring gear.

• 한국생산제조학회지
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• 제24권3호
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• pp.320-326
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• 2015

Despite the wide industrial applications of planetary gear trains, the relationship between the design parameters (tooth profile, carrier mass, etc.) and performance (strength, vibration, noise, etc.) remains poorly understood. A significant amount of research has focused on transmission errors, which are measurable performance indicators directly related to the design parameters. Herein, an experimental test rig for a single-stage planetary gear set built using digital angular encoders and gap sensors is described. To study the static and dynamic characteristics of this planetary gear train, the transmission errors and sun gear orbit are analyzed from the data measured under various levels of torque and speed. The transmission errors of the gear train decrease 40% when the speed increases from 30 to 600 rpm with an output torque of 39.2 Nm, and increase 22% when the output torque increases from 19.6 to 39.2 Nm with an input speed of 30 rpm.

• 소성∙가공
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• 제13권8호
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• pp.723-730
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• 2004

This paper describes the analysis of extrusion process and integrity for a condenser tube which is a component of the heat exchanger in automobile and all conditioning apparatus. Recently, according to the development of analysis method using the computer, the numerical simulation have been applied to the 3-dimensional hot extrusion process with complex section area of the non-steady statement and then results of the analysis have been applied to optimal die design and process design. In this paper, firstly, the die design was performed for a condenser tube with a multi-hole section and the rigid-plasticity FE analysis performed of extrusion process. Secondly, we estimated metal flow of billet, extrusion load, welding pressure in chamber etc. and evaluated the pressure and elastic strain of the die land and mandrel tooth profile through a stress analysis of the die. Finally, the extrusion test was performed to estimate the validity of FE analysis. This paper confirmed that the designed extrusion die of the research is satisfactorily designed fur integrity of condenser tube.

• 대한치과보철학회지
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• 제39권3호
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• pp.306-312
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• 2001

Achieving an aesthetic implant-supported restoration in the single tooth missing case can be challenging when the implant site is in e anterior region. The objective of this report is to focus on presurgical evaluation of implant site and systematic development of related prosthetic modalities. An accurate diagnostic evaluation, a systematically developed pesurgical plan, and knowledge and clinical skill of the various related therapeutic modalities are indispensible. Collection of patient's information, appropriate abutment selection, soft tissue contour, implant axis, and occlusion need to be discussed for aesthetic clinical outcome. For aesthetic restoration, such as surgical guide stent for precise implant positioning customized provisional restoration for development of optimal periimplant soft tissue contours, and fabrication customized abutment (mesiostructure) for veriable emergence profile, are recommended.

• 한국정밀공학회지
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• 제32권11호
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• pp.977-982
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• 2015

This study uses finite element analysis to evaluate the forming load of tool entrance angle of the cold forward extrusion molding process of helical gear; this can replace the spur gear applied to the Electronic Parking Brake (EPB) system. A cold forging process is often used in the automobile industry as well as in various industrial machines due to its high efficiency. Finite element analysis is frequently used when interpreting results of the forging process. Formality was evaluated by calculating tooth profile filling rate of helical gear. Change in required forming load was investigated when the entrance angle of forward extrusion tool die was changed from $30^{\circ}$ to $60^{\circ}$, also by finite element analysis. We suggest suitable tool entrance angles.

• 대한안전경영과학회지
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• 제20권4호
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• pp.1-6
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• 2018

Recently, bicycle has means of effective healthy transportation, and riding the bicycles is considered as popular recreational and sporting activities. Also, the saddle, steering system, driving device and braking device are researched briskly because of consumer's need for driving performance and comfort. Especially, the importance of a cassette responsible for transmission function by transmitting power to the drive shaft through the chain is very focused. The writer conducted structural analysis for the sprocket of each level using the ANSYS widely used for the analysis. Speed shifting performance was enhanced by minimization / simplification of shifting point through a sort of tooth profile of the cassette. By partitioning a clear value type and other shifting point, it has been modified to enable smooth speed-shifting. In addition, as titanium precision forming process, this study studied the molding technique by blanking and dies forging for mass production of the cassette. so it could be expected that the entire drive train would utilize that in the future. The stamping process capability for thin materials for the mass production of the sprockets is applicable to producing automobile parts, so lightweight component production is likely to be possible through that, for the safety of driving.

• 치위생과학회지
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• 제9권4호
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• pp.475-483
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• 2009

한국 노인을 대상으로 외국에서 비교적 높은 신뢰도와 타당도가 입증된 Oral Health Impact Profile 14(OHIP 14)를 한국의 문화적 특성이나 사고방식에 맞게 번역하여 강릉시에 거주하는 노인 만 65세 이상 668명을 대상으로 2005년 1월부터 2월까지 2개월간 OHIP 14 지표의 신뢰도와 타당도를 검증(Kappa index, Cronbach's alpha Correlation & Spearman ranked correlation coefficient)하고, OHIP 14와(구강)건강인식도, 구강건강상태, 전신건강 상태와의 차이를 검증(Kruskal Wallis test, Mann-Whitney U-test)함으로써, 향후 우리나라 노인 구강건강문제를 포괄적으로 파악하기 위한 지표로 활용할 수 있는 지를 검토하고자 하였다. 1. (구강)건강인식도와 OHIP 14는 전신건강인식도, 구강건강인식도, 치과치료필요도, 구강건강만족도, 통증에 대한 시각적 정도, 틀니만족도, 구강건강상태와 OHIP 14는 무치악 여부, 현존 자연치아의 개수, 치아치료필요, 전신건강상태와 OHIP 14는 질병의 개수, 치매, 눈, 귀, 호흡기, 심혈관, 소화기, 비뇨생식기, 근골격계, 신경계, 심리상태가 상관관계가 있는 것으로 나타났다. 2. (구강)건강인식도에 따른 OHIP 14는 전신건강인식도, 구강건강인식도, 치과치료필요도, 구강건강만족도, 통증에 대한 시각적 정도, 틀니만족도, 구강건강상태에 따른 OHIP 14는 무치악 여부, 치아치료필요, 현존 자연치아의 개수, 전신건강상태에 따른 OHIP 14는 치매, 귀, 호흡기, 심혈관, 소화기, 근골격계, 신경계, 심리상태에서 현저한 차이를 보였다. 본 연구는 일부 노인에서 임상지표를 이용한 OHIP 14에서 (구강)건강인식도, 구강건강상태, 전신건강상태가 OHIP 14와의 타당도와 연관성이 있다는 사실을 일부에서 확인할 수 있었다. 이상의 결과로 향후 한국노인의 구강건강문제를 포괄적으로 파악하는데 전통적인 구강건강 상태검사, 전신건강상태검사와 더불어 '구강건강 관련 삶의 질' 지표인 OHIP 14를 활용할 수 있을 것으로 사료된다.