• 한국안광학회지
• /
• 제17권4호
• /
• pp.403-410
• /
• 2012

목적: 정시와 안경 및 콘택트렌즈 착용자의 조절반응량을 비교하고, 각 그룹내에서 굴절이상도와 조절래그의 상관성을 확인하고자 하였다. 방법: 안질환이 없고 굴절이상이 완전 교정된 72명(144안)을 대상으로 폐쇄형 자동굴절검사기로 측정한 굴절이상도를 사용하여 정시, 안경착용자 및 콘택트렌즈 착용자로 분류하였다. 이후 우세안, 나안시력 및 교정시력을 측정하고, 개방형 자동굴절검사기를 이용하여 단안 및 양안으로 원/근거리(5 m/33 cm)를 주시할 때의 굴절이상도를 측정하여 조절래그를 산출하였다. 결과: 좌우안 및 우세안/비우세안의 조절래그는 단안/양안주시 모두 통계적으로 유의한 차이가 없었으며, 단안주시의 조절래그가 양안주시보다 더 크게 검출되었다. 또한 남녀간의 조절래그는 단안주시는 남자가 컸지만 양안주시는 유의한 차이가 없었다. 근시도와 조절래그는 단안/양안주시 모두 근시안이 정시안에 비해 더 컸지만, 안경착용자와 콘택트렌즈 착용자의 조절래그는 단안/양안주시 모두 유의한 차이는 없었다. 전체 대상자의 굴절이상도와 조절래그 상관성은 단안/양안주시 모두 굴절이상도가 클수록 조절래그가 컸으며, 정시안과 콘택트렌즈 착용자는 단안/양안주시 모두 유의한 상관성이 있었으나 안경착용자는 단안/양안주시 모두 유의한 상관성이 없었다. 결론: 정시안과 근시안의 조절래그는 유의한 차이가 있고, 근시안 중 안경착용자와 콘택트렌즈 착용자의 조절래그는 유의한 차이가 없었다. 정시안과 콘택트렌즈 착용자의 굴절이상도는 조절반응량과 상관성을 보였다.

• 한국근적외분광분석학회:학술대회논문집
• /
• 한국근적외분광분석학회 2001년도 NIR-2001
• /
• pp.1524-1524
• /
• 2001

A previous paper(Ito et al., 2000) has described the improvement of the standard error(SEC and SEP) of the predicted soluble solids(Brix) in a melon cultivar by non-contact mode with a fiber optic probe. Then we examined the immature and mature fruits. The objective of this study was to determine if non-contact mode could improve the standard error of the predicted Brix of matured melon fruits from cross progeny as well as the contact mode(usual method). The optical absorption spectrum was measured using a NIR Systems model 6500 spectrophotometer. A commercial spectral program(NSAS ver. 3.27) was used for multiple linear regression analysis. Absorbances of 902 and in the vicinity of 877 nm were included as the independent variables in both multiple regression equations. These wavelengths are key wavelengths for non-destructive Brix determination. When the results for the contact mode and non-contact mode are compared, the latter mode improved the former standard error(SEP and RMS).

• 한국생산제조학회지
• /
• 제22권4호
• /
• pp.735-739
• /
• 2013

The error motion of a machine tool spindle directly affects the surface errors of machined parts. Spindle motion errors such as three translational motions and two rotational motions are undesirable. These are usually due to the imperfectness of bearings, stiffness of spindle, assembly errors, and external force or unbalance of rotors. The error motions of the spindle need to be reduced for achieving the desired performance. Therefore, the level of error motion needs to be estimated during the design and assembly process of the spindle. In this study, an estimation method for five degree-of-freedom (5 DOF) error motions for a spindle with an angular contact ball bearing is suggested. To estimate the error motions of the spindle, the waviness of the inner-race of bearings and an external force model were used as input data. The estimation model considers the geometric relationship and force equilibrium of the five DOFs. To calculate the error motions of the spindle, not only the imperfections of the shaft and bearings but also driving elements such as belt pulley and direct driving motor systems are considered.

• 한국정밀공학회지
• /
• 제25권5호
• /
• pp.69-76
• /
• 2008

Inner diameter of bearing race is automatically measured by complete inspection system after grinding process. Contact type three points supporting method is widely applied to automatic inner diameter measurement because of its excellent stability. However, the geometric consideration regarding three points supporting method is not sufficient. In this study, the error equation from geometric error analysis of three points supporting method is found. The effect of factors in the error equation is also investigated. The error equation is linear for difference of diameter in sample and master on range of tolerance. An error becomes more and more larger, when the distance of two supporting balls or the diameter of supporting ball are increased. In the result, some considerations are proposed for measurement of inner diameter by the three points supporting method.

• 대한통합의학회지
• /
• 제8권4호
• /
• pp.307-321
• /
• 2020

Purpose : A person infected by SARS-CoV2 may present various symptoms such as fever, pain in lower respiratory tract, and pneumonia. Measuring body temperature is a simple method to screen patients. However, changes in the surrounding environment may cause errors in infrared measurement. Hence, a non-contact thermometer controls this error by setting a correction value, but it is difficult to correct it for all environments. Therefore, we investigate device error values according to changes in the surrounding environment (temperature and humidity) and propose guidelines for reliable patient detection. Methods : For this study, the temperature was measured using three types of non-contact thermometers. For accurate temperature measurement, we used a water bath kept at a constant temperature. During temperature measurement, we ensured that the temperature and humidity were maintained using a thermo-hygrometer. The conditions of the surrounding environment were changed by an air conditioner, humidifier, warmer, and dehumidifier. Results : The temperature of the water bath was measured using a non-contact thermometer kept at various distances ranging from 3~10 cm. The value measured by the non-contact thermometer was then verified using a mercury thermometer, and the difference between the measured temperatures was compared. It was observed that at normal surrounding temperature (24 ℃), there was no difference between the values when the non-contact thermometer was kept at 3 cm. However, as the distance of the non-contact thermometer was increased from the water bath, the recorded temperature was significantly different compared with that of mercury thermometer. Moreover, temperature measurements were conducted at different surrounding temperatures and the results obtained significantly varied from when the thermometer was kept at 3 cm. Additionally, it was observed that the effect on temperature decreases with an increase in humidity Conclusion : In conclusion, non-contact thermometers are lower in lower temperature and dry weather in winter.

• 한국융합학회논문지
• /
• 제9권12호
• /
• pp.273-279
• /
• 2018

본 연구는 굴절이상도와 조도가 써클콘택트렌즈 착용 시 대비감도에 어떠한 영향을 미치는 지 조사하였다. 연구대상자는 총 16명(남5명, 여 11명)을 대상으로 하였다. 대비감도는 나안상태, 써클 콘택트렌즈의 색상별, 검사실의 조도에 따라 측정하였다. 조도에 따른 대비감도는 컬러콘택트렌즈를 착용했을 때 나안상태보다 감소하였고, 암소시보다 명소시일 때 대비감도가 증가하였다. 브라운과 블랙 두 가지 컬러 콘택트렌즈의 대비감도를 비교하였을 때 블랙보다는 브라운 컬러의 콘택트렌즈에서 대비감도가 높았다. 또한 굴절이상유무에 따른 정시안, 근시안, 근시성난시안 대상자의 대비감도 비교에서 정시안대상자에서 조도에 따른 대비감도가 유의한 차이를 보였다. 이는 컬러콘택트렌즈 착용자들의 충분한 이해와 인식이 필요할 것이라고 사료된다.

• 한국정밀공학회지
• /
• 제16권6호
• /
• pp.148-159
• /
• 1999

A numerical method is presented for the dynamic analysis of spur gears rotating with very high angular speeds. For an efficient computation each gear is assumed to consist of a rotating rigid disk and an elastic tooth having mass, and finite element formulations are used for the equations of motion of the tooth. The geometric constraint is imposed between the rigid disk and the elastic tooth to fix them, and contact condition is imposed between the meshing teeth of the gears. At each iteration of each time step the Lagrange multiplier and contact force are revised by using the constraint error vector, and then the whole equations of motion are time integrated with the given Lagrange multiplier and contact force. For the accurate solution the velocity and acceleration constraints as well as the displacement constraint are satisfied by the monotone reductions of the constraint error vectors. Computing procedures associated with the iterative schemes are explained and numerical simulations are conducted with the spur gears.

• 한국기계가공학회지
• /
• 제11권5호
• /
• pp.42-47
• /
• 2012

Construction equipment is heavily loaded during normal operation. In recent years, there is a trend that lower gear noise levels are demanded for drivers to avoid annoyance and fatigue during operation. For articulated hauler's final drive, meshing transmission error(T.E.) is the excitation that leads the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. This paper presents a method for the analysis of the tooth profile modification, and the prediction of transmission error under the loaded torques for the spur gear pair of the articulated hauler's final drive. And the transmission error, transmission error harmonics and contact stress are also calculated and compared before and after tooth modification under one torque. The simulation result shows that the transmission error and contact stress under the loads can be minimized by the appropriate tooth profile modification.

• Journal of Biosystems Engineering
• /
• 제25권3호
• /
• pp.233-240
• /
• 2000

A commercially available Doppler radar was modified and evaluated for on-board monitoring of ground speed. The radar output was corrected for pitch angle of aircraft based on the output of an electrolytic tilt sensor. The effects of aircraft speed, height and mounting angle on error in the ground speed were evaluated. The speed error decreased with an increase of the mounting angle since the radar contact angle with respect to the ground approached to the mounting angle. The error increased with an increase of the nominal aircraft speed. The altitude insignificantly affected the speed error. The Doppler radar provided acceptable percent errors within 5% in most measurements. The error can be reduced within ${\pm}$1.5% by increasing the mounting angle ($43^{\circ}$). The error of -3.8% at the mounting angle of $29^{\circ}$could be reduced by adjusting the mounting angle with respect to the radar contact angle.

• 한국기계가공학회지
• /
• 제10권4호
• /
• pp.70-75
• /
• 2011

Nowadays, modern gearboxes are characterized by high torque load demands, low running noise and compact design. Also durability of gearbox is specially a major issue for the industry. For the gearbox which used in wind turbine, gear transmission error(T.E.) is the excitation that leads the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. In this paper, tooth modification for the high speed stage is used to compensate for the deformation of the teeth due to load and to ensure a proper meshing to achieve an optimized tooth contact pattern. The gearbox is firstly modeled in Romax software, and then the various combination analysis of the tooth modification is presented by using Windows LDP software, and the prediction of transmission error under the loaded torque for the helical gear pair is investigated, the transmission error, contact stress, root stress and load distribution are also calculated and compared before and after tooth modification under one torque condition. The simulation result shows that the transmission error and stress under the loads can be minimized by the appropriate tooth modification.