• Journal of Advanced Marine Engineering and Technology
• /
• 제7권1호
• /
• pp.34-39
• /
• 1983

Development of modern internal combustion engine requires more precise indicator. In the case of strain gage-strain tube type indicator, thermal expansion of the indicator's fixed part makes zero-shift in spite of water cooling. Therefore, the authors analyzed the cause of zero-shift phenomenon on strain gage-strain tube type indicator and proposed a new device to compensate the zero-shift of indicator by electrical method without detoriorating the dynamic charcteristic. As the results, we found that the zero-shift is varied linearlly according to temperature variation of the indicator's fixed part and appling a new device, we can improve the zero-shift of indicator about 0.63% (0.63 kg/$cm^2$) of full scale, though we got 10% of it without the device at the cylinder head operating temperature (c.a. $200^{\circ}C$).

• 한국자동차공학회논문집
• /
• 제21권5호
• /
• pp.34-39
• /
• 2013

The gear shifting timing of a manual transmission vehicle is influencing fuel economy. This paper focuses on an gear shifting indicator of an city bus with manual transmission, which can improve fuel economy. The shift indicator is supposed to collect the vehicle data during driving, calculate and compare fuel economy with and without gear shifting, and indicate the proper gear shifting timing. The H/W and S/W of the shift indicator are developed and tested on city bus in this research. The experiments are carried out on real road by 3 different drivers and the results show the improvement of fuel economy from 6.0% to 21.4%. The average engine torque and speed are reduced due to early gear shifting and the usage of highest gear is increased. The results of chassis test are also performed and show 7.5% improvement of fuel economy.

• 대한기계학회논문집A
• /
• 제27권5호
• /
• pp.758-763
• /
• 2003

A profile shifted gear system was analyzed to select the optimum profile shift coefficient, which minimizes gear teeth deflection. Contact force and deformation overlap were calculated by means of FEM and contact theory. The deformation overlap is suggested for an effective indicator to represent the whole deformation of gear system. The optimum value of profile shift coefficients was presented with respect to the deformation of gear system.

• Annals of Occupational and Environmental Medicine
• /
• 제35권
• /
• pp.4.1-4.11
• /
• 2023

Background: Shift work has been shown to increase the risk of cardiovascular disease (CVD) based on several evidences. The classic risk factors of CVD include age, hypertension, smoking, obesity and diabetes. Recently, the serum homocysteine level has been reported to be a valuable indicator of CVD risk. This study aimed to determine the variation in serum homocysteine level as a cardiovascular risk indicator among female workers according to shift work. Methods: The data of regular health examination of workers at an electronic manufacturing services company in Yeongnam region, South Korea in 2019 were examined in this study. The investigation was based on a cross-sectional study conducted on 697 female workers (199 day workers and 498 shift workers). The sociodemographic and biochemical characteristics were compared between day workers and shift workers. Through a logistic regression analysis, the odds ratio (OR) of the increased serum homocysteine level in relation to shift work was determined. Results: Compared to female day workers, female shift workers showed significantly higher level of serum homocysteine (8.85 ± 2.16 vs. 9.42 ± 2.04 μmol/mL; p = 0.001). The OR of day workers against shift workers was 1.81 (95% confidence interval [CI]: 1.25-2.63). With the adjustment of variables that may influence the level of serum homocysteine, the adjusted OR was 1.68 (95% CI: 1.09-2.60). Conclusions: The serum homocysteine level was significantly higher in shift workers than in day workers. It is thus likely to be a useful predictor of CVD in shift workers.

• Annals of Occupational and Environmental Medicine
• /
• 제34권
• /
• pp.35.1-35.12
• /
• 2022

Background: Shift work is known to be associated with cardiovascular disease (CVD). It has been found that inflammatory reactions are involved in the onset and progression of CVD. Therefore, the purpose of this study was to investigate the association between shift work and inflammatory markers. Methods: Among workers at an electronics manufacturing company, 2,329 workers who had a health checkup from January 2019 to December 2019 were targeted. The general and biochemical characteristics of daytime workers and shift workers were compared through the Independent-test and the χ² test. Through multiple linear regression analysis, the association with shift work and inflammatory markers was investigated. Through multiple logistic regression analysis, the association with shift work and high inflammatory markers Results: The mean total leukocytes, neutrophils, monocytes, lymphocytes of shift workers were significantly higher than those of daytime worker. The mean high-sensitivity C-reactive protein (hs-CRP) of shift workers was also higher than that of daytime workers but not significantly. In multiple linear regression, shift work was associated with increase of total leukocyte count (β = 0.367, p < 0.001) and hs-CRP (β = 0.140, p = 0.005) after adjusting for all variables. In multiple logistic regression analysis, shift work showed 2.27 times risk of high leukocyte count and 1.8 times risk of high hs-CRP level compared to daytime work after adjusting for all variables. Conclusions: This study confirmed that shift work is associated with high inflammatory markers. Considering that high inflammatory markers is independent indicator of CVD, the association between shift work and high inflammatory markers may help to understand the CVD risk of shift workers.

• 조명전기설비학회논문지
• /
• 제27권3호
• /
• pp.1-6
• /
• 2013

In this study, we propose a fiber-optic hydrogen sensor using a polarization-diversity loop configuration composed of a polarization beam splitter, two quarter-wave plates, and a polarization-maintaining fiber coated with palladium whose thickness is ~400nm. One transmission dip of the output interference spectrum of the proposed sensor, chosen as a sensor indicator, was observed to spectrally shift with the increase of the hydrogen concentration, and the sensing indicator showed a wavelength shift of ~2.48nm at a hydrogen concentration of 4%. Except for a hydrogen concentration of 4%, the response time of the proposed sensor was measured as less than 12.5s and did not show significant dependence on the hydrogen concentration. In particular, the proposed fiber hydrogen sensor is more durable and highly resistant to external stress applied on a transverse axis of an optical fiber, compared with other hydrogen sensors based on side-polished fibers or fiber gratings.

• 환경위생공학
• /
• 제11권3호
• /
• pp.1-7
• /
• 1996

Mandelic acid is the major metabolite and phenylglyoxylic acid is the minor metabolite of styrene in human. This study was conducted to investigate the correlation between exposure concentrations of styrene and concentration of the metabolites in urine The concentrations of metabolites in urine and exposure concentrations were measured in 60 workers who were occupationally exposed to styrene in FRP industry as well as paint industry and musical instrument manufacturing industry and the concentrations of metabolites in urine ware measured in 90 workers not occupationally exposed to styrene for review the background level in the unexposed population. The results obtained were as follows; 1. The mean exposure concentration is 16.6 $\pm $12.2 ppm (range 0.4-49.9ppm) in the styrene exposed workers. 2. The concentration of mandelic acid in urine collected at the end of shift from worker exposed 8 hours to 50ppm of styrene, based on extrapolation from correlation equations was 578.5 mg/g creatinine and 176.8 mg/g creatinine for next morning urine, the concentration of phenylglyoxylic acid in urine collected at the end of shift was 291.1 mg/g creatinine, 177.9 mg/g creatinine in next morning urine. In the sum of mandelic acid and phenylglyoxylic acid in the urine 870.2 mg/g creatinine in urine sampled at the end of shift corresponds to an exposure of 50ppm of styrene and 366.0 mg/g creatinine for next morning sample corresponds to 50ppm. 3. The correlation of the degree of exposed with sum concentration of mandeliacid and phenylglyoxylic acid in the urine was better(r=0.079 for end of shift, r=0.78 for next morning) than the correlation with single determinant measurement in urine(r=0.75 for mandelic acid at end of shift, r=0.73 for mandelic acid at next morning, r=0.69 for phenylglyoxylic acid at end of shift, r=0.62 for phenylglyoxylic acid at next morning). The monitoring of sum concentration of mandelic acid and phenylglyoxylic acid in urine is a valuable indicator of time weighted average daily exposure ti styrene. And the exposure standard of urinary metabolites produced by styrene should be set, in distinction urine at the end of shift from urine at next morning.

• 국제학술발표논문집
• /
• The 6th International Conference on Construction Engineering and Project Management
• /
• pp.44-48
• /
• 2015

Housing price is a key indicator of housing demand. Actual Transaction Price Index of Apartment (ATPIA) released by Korea Appraisal Board is useful to understand the current level of housing price, but it does not forecast future prices. Big data such as the frequency of internet search queries is more accessible and faster than ever. Forecasting future housing demand through big data will be very helpful in housing market. The objective of this study is to develop a forecasting model of ATPIA as a part of forecasting housing demand. For forecasting, a concept of time shift was applied in the model. As a result, the forecasting model with the time shift of 5 months shows the highest coefficient of determination, thus selected as the optimal model. The mean error rate is 2.95% which is a quite promising result.

• Journal of Ecology and Environment
• /
• 제46권4호
• /
• pp.292-303
• /
• 2022

Background: Climate change significantly influences the geographical distribution of plant species worldwide. Selecting indicator species allows for better-informed and more effective ecosystem management in response to climate change. The Korean Peninsula is the northernmost distribution zone of warm temperate evergreen broad-leaved (WTEB) species in Northeast Asia. Considering the ecological value of these species, we evaluated the current distribution range and future suitable habitat for 13 WTEB tree species designated as climate-sensitive biological indicator species. Results: Up-to-date and accurate WTEB species distribution maps were constructed using herbarium specimens and citizen science data from the Korea Biodiversity Observation Network. Current northern limits for several species have shifted to higher latitudes compared to previous records. For example, the northern latitude limit for Stauntonia hexaphylla is higher (37° 02' N, Deokjeokdo archipelago) than that reported previously (36° 13' N). The minimum temperature of the coldest month (Bio6) is the major factor influencing species distribution. Under future climate change scenarios, suitable habitats are predicted to expand toward higher latitudes inland and along the western coastal areas. Conclusions: Our results support the suitability of WTEB trees as significant biological indicators of species' responses to warming. The findings also suggest the need for consistent monitoring of species distribution shifts. This study provides an important baseline dataset for future monitoring and management of indicator species' responses to changing climate conditions in South Korea.

• 한국농촌건축학회논문집
• /
• 제18권1호
• /
• pp.47-56
• /
• 2016

Urban planning is the task to explore measures for bringing order to the change in urban space of future predicted in relation to the size and purpose of the land and a variety of facilities in cities in order to present the environment that can promote the qualitative improvement of activities of residents, ensure orderly urban space of future, and create appropriate urban environment which meets the desire of citizens by anticipating the urban development on the basis of overall activities such as politics, economics, culture, etc, so that the improvement in urban life can be accomplished ultimately. Therefore, this study attempted to examine current conditions information necessary for establishing policies pursuant to the national land development plan and regional development, as well as respond to the needs of urban residents who need the improvement of settlement environment including various amenities for the convenience of life, by shifting away form the macroscopic and one-size-fits top-down approach of development so far and aiming a balanced development of national land in quest for welfare society and by utilizing the urban index as the basic prior task necessary for seeking the shift ind the direction of policies and setting the direction for policies on the basis of the top-down development approach which suits the anticipation and hope of local residents as the subject of development, considering the growing interest in the shift in the policies for regional development in this era of localization. Techniques for urban planning need to be applied, such as the prior planning and the following development, along with the support at the policy level for achieving the improvement in the related sector, in order to induce continuos urban deelopment based on the establishment of healthy and sound settlement environment, and furthermore, the efforts must be drven forward to improve the urban settlement environment while the urban planning and policies are established.