• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.6
• /
• pp.78-89
• /
• 1996

Every mechanical component is fabricated with the variations in its size and shape, and the allowable range of the variation is specified by the tolerance in the design stage. Geometric tolerances specify the size or the thickness of each shape entity itself or its relative position and orientation with respect to datums. Since the range of shape variation can be represented by the variation of the coordinate system attached to the shape, the transformation matrix of the coordinate system would mathematically express the range of shape variation if the interval numbers are inserted for the elements of the transformation matrix. For the shape entity specified by the geometric tolerance with reference to datums, its range of variation can be also derived by propagating the transformation matrices composed of interval numbers. The propagation depends upon the order of precedence of datums.

• Journal of Korean Society for Atmospheric Environment
• /
• v.7 no.3
• /
• pp.219-226
• /
• 1991

Results from study on physiological responses to $SO_2$ of Quercus spp. selected for restoration of vegetation damaged by air pollution in the field study were as follows. Tolerance of Quercus aliena, Q. acutissima and Q. mongolica used in this study to $SO_2$ was higher in that order and tolerance of these plants to $SO_2$ was high comparatively among trees composing of major forest vegetation of Korea including natural forests and plantations. Stomatal resistance of these plants was increased after exposure to $SO_2$ and range of increase was different among species. From discrepancy between order of tolerance to $SO_2$ and range of increase in stomatal resistance, we were estimated that resistance mechanisms of Quercus spp. were different among species as mechanism originated in avoidance and resistance, respectively. Water potential of plant leaves reduced after exposure to $SO_2$, degree of reduction accorded with order of tolerance to $SO_2$. Reduction of water potential of plants after exposure to $SO_2$ was initiated before appearance of visible damage in plant leaves and water potential of plants exposed to $SO_2$ of low concentration, in which plants were not showed viaible damage was also reduced.

• Korean Journal of Ecology and Environment
• /
• v.43 no.4
• /
• pp.459-470
• /
• 2010

In this study, we analyzed fish tolerance guilds in mainstems and tributaries of 65 streams and rivers arid their relations to water quality using dataset sampled from April to November, 2009. For the study, water quality parameters including biochemical oxygen demand (BOD), electric conductivity (EC), total nitrogen (TN), total phosphorus (TP), ammonia nitrogen ($NH_3$-N), nitrate nitrogen ($NO_3$-N) and phosphate phosphorus ($PO_4$-P) were analyzed in the laboratory and also tolerance ranges in 3 category fishes of sensitive, intermediate, and tolerant species with high abundance were analyzed. According to fish guild analysis, tolerant species was 58% of the total community and the proportion of omnivore species was 63% of the total, indicating a degradation of habitats and water quality. Water quality was shown typical longitudinal gradients from the headwater to the down-river; TN and TP increased toward the down-rivers except for the big point-source area and ionic contents, based on, electric conductivity showed same pattern. Tolerance guild analysis of 9 major species with high abundance indicated that sensitive groups had narrower tolerance range in the water quality than the groups of intermediate and tolerant species. In contrast, tolerant groups including Zacco platypus, Carassius auratus, and Opsarichthys uncirostris amurensis had wider tolerance ranges than the groups of sensitive and intermediate species. Thus, each group was evidently segregated from the tolerance levels. Principal Component Analysis (PCA) employed for the relations of water quality to fish species in each groups suggests that water quality had highest eigenvalues with fish species in the 1st axis of the PCA and nitrogen (TN, $NH_3$-N, $NO_3$-N) and phosphorus (TP) were key components differentiating three groups of sensitive, intermediate and tolerance guilds.

• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.197-200
• /
• 2002

UVR-induced immunosuppression contributes to skin cancer. The aim was to construct accurate dose response curves for primary and secondary contact sensitivity for solar-simulated UVR (ssUVR; 290-400nm), UVA and UVB as the role of UVA in immunosuppression is controversial. We used a xenon arc source. The mice were immobilised, enabling accurate dosing. C57BL/6 mice were immunosuppressed at half the dose of ssUVR required to cause sunburn but not by higher doses (up to the sunburn dose). Thus, ssUVR causes systemic immunosuppression only over a narrow, low dose range. UVA caused suppression at low but not high doses whereas UVB induced immunosuppression at all doses tested. 8 weeks later the mice were resensitised to assess tolerance. Mice exposed to the minimum immunosuppressive dose of ssUVR prior to primary sensitisation were tolerant to re-sensitisation. However, at higher doses of ssUVR, these mice were protected from tolerance. Interestingly, while low doses of UV A caused immunosuppression, even lower doses enhanced the response to the second sensitisation. Higher doses of UVA had no affect. UVB induced tolerance in a dose related manner. Thus, ssUVR only induces immunosuppression and tolerance over a narrow dose range. Both UVA and UVB are immunosuppressive at this dose, while higher doses of UVA protect from the suppressive effects of UVB. Surprisingly very low doses of UVA enhanced memory development. Thus UVR has complex effects on the immune system depending on dose and spectrum.

• International Journal of Safety
• /
• v.6 no.1
• /
• pp.1-6
• /
• 2007

Operation of human-centered robot, in general, facilitates the creation of new process that may potentially harm the human operators. Design of safety-guaranteed operation of human-centered robots is, therefore, important since it determines the ultimate outcomes of operations involving safety of human operators. This study discusses the application of geometric tolerance and head injury criteria to safety assessment of human-centered robotic operations. Examples show that extending "Work Area" has more significant effect on the uncertainty in safety than extending the system range in the presence of velocity control.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.12
• /
• pp.75-83
• /
• 2010

Every mechanical part for mass production has dimensions with tolerances in engineering drawing. Tolerance is given to guarantee assemble parts together satisfying functional requirements and dimensional constraints. Tolerance is essential factor for standardization of parts or assembly and has huge influence on manufacturing cost. It will be desirable to have tolerances as broad as possible for minimizing manufacturing cost. This paper describes tolerance analysis of u-joint assembly that is a part of automobile steering system. Within the range of tolerances of parts, accumulated effect is estimated by arithmetic calculation, probability theory and Monte carlo simulation. Each result is compared to investigate the method for increasing productivity.

• The Korean Journal of Community Living Science
• /
• v.17 no.2
• /
• pp.49-60
• /
• 2006

It was measured the energy expenditure in each season, the cold tolerance in winter and the heat tolerance in summer. Farmers' adaptability to the change of environment was compared with those of city-dwellers such as indoor workers and street cleaners to determine the effect of living environment, especially living temperature, on the health of human body. It turned out that farmers had experienced wide range of temperature that was higher in summer and lower in winter than indoor workers. Farmers and street cleaners showed seasonal adaptation in energy expenditure, which was high in winter and low in summer. However, indoor workers did not show seasonal changes. Energy expenditure had an inverse correlation with the temperature in work place where subjects spend the longer time in a day except in female indoor workers in Seoul. And It was proved that farmers and street cleaners had stronger cold tolerance and heat tolerance than indoor workers.

• Journal of KIISE
• /
• v.42 no.2
• /
• pp.242-254
• /
• 2015

In this paper, we address the problem of improving the performance of multi-step k-NN search using multi-dimensional indexes. Due to information loss by lower-dimensional transformations, existing multi-step k-NN search solutions produce a large tolerance (i.e., a large search range), and thus, incur a large number of candidates, which are retrieved by a range query. Those many candidates lead to overwhelming I/O and CPU overheads in the postprocessing step. To overcome this problem, we propose two efficient solutions that improve the search performance by reducing the tolerance of a range query, and accordingly, reducing the number of candidates. First, we propose a tolerance reduction-based (approximate) solution that forcibly decreases the tolerance, which is determined by a k-NN query on the index, by the average ratio of high- and low-dimensional distances. Second, we propose a coefficient control-based (exact) solution that uses c k instead of k in a k-NN query to obtain a tigher tolerance and performs a range query using this tigher tolerance. Experimental results show that the proposed solutions significantly reduce the number of candidates, and accordingly, improve the search performance in comparison with the existing multi-step k-NN solution.

• Applied Chemistry for Engineering
• /
• v.21 no.4
• /
• pp.411-416
• /
• 2010

In this research, we intended to improve the tolerance of thick film resistor using photosensitive polymer resistor paste which was fabricated with alkali-solution developable photosensitive resin and conductive carbon black. At first, we investigated the effect of the selection of carbon black and photosensitive resin on the resistance range and tolerance level of polymer thick film resistor (PTFR). And then, a difference in resistance tolerance was evaluated according to the coating methods of photosensitive resistor paste on test board. In case that the photosensitive resistor paste was coated on whole surface of test board using screen printing, large positional tolerance was obtained because the formation of the thick film with uniform thickness was difficult. On the other hand, when the paste was coated with roller, the resistive thick film with uniform thickness was formed on the whole board area and the result of resistance evaluation showed low tolerance in ${\pm}10%$ range. The tolerance of PTFR could be improved by combination of the precise patterning using photo-process and the coating process for the resistive thick film with uniform thickness.

• Journal of Power Electronics
• /
• v.18 no.6
• /
• pp.1619-1626
• /
• 2018

The output power of most facilities for renewable energy generation is unstable due to external environmental conditions. In distributed power systems with two or more sources, a stable output can be achieved with the complementary power supply among the different input sources. In this paper, a double-input DC-DC converter with a wide-input-voltage-range is proposed for renewable energy generation. This converter has the following advantages: the circuit is simple, and the input voltage range is wide and the fault tolerance is excellent. The operation modes and the steady-state analysis are examined. Finally, experimental results are illustrated to verify the correctness of the analysis and the feasibility of the proposed converter.