• Safety and Health at Work
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• v.8 no.2
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• pp.151-155
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• 2017

Background: At the entrance of a tunnel, reflection of sunlight from the surrounding environment and a lack of adequate lighting usually cause some vision problems. The purpose of this study was to perform a safety evaluation of lighting on a very long road in Ilam, Iran. Methods: The average luminance was measured using a luminance meter (model S3; Hagner, Solna, Sweden). A camera (model 108, 35-mm single-lens reflex; Yashica, Nagano, Japan) was used to take photographs of the safe stopping distance from the tunnel entrance. Equivalent luminance was determined according to the Holliday polar diagram. Results: Considering the average luminance at the tunnel entrance ($116.7cd/m^2$) and using Adrian's equation, the safe level of lighting at the entrance of the tunnel was determined to be 0.7. Conclusion: A comparison between the results of the safe levels of lighting at the entrance of the tunnel and the De Boer scale showed that the phenomenon of black holes is created at the tunnel entrance. This may lead to a misadaptation of the drivers' eyes to the change in luminance level at the entrance of the tunnel, thereby increasing the risk of road accidents in this zone.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.133-137
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• 2019

This study was conducted to clarify the morphological characteristics of Siberian flying squirrel (Pteromys volans). We investigated 6 morphological characteristics from April, 2014 to March 2016 at Mt. Baekwoon, Wonju, Gangwon province. We found that Siberian flying squirrel showed female-biased sexual dimorphism. This result would be related to reproductive strategy of the species which female nurse offspring alone. As results of comparison of morphological characteristics from Korea, Finland and Japan, both body weight and head-body length appeared heavier and longer from high-latitude to low-latitude. This result suggest that morphological difference between different latitudes would be related with climate and habitat environment. The more researches would be needed with other morphological characteristics of Siberian flying squirrel.

• Journal of The Korean Association For Science Education
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• v.27 no.3
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• pp.201-211
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• 2007

The purposes of this study were to examine trends in Korean middle school students' attitudes toward science and the differences in boys' and girls' attitudes toward science as well as to analyze Korean middle school students' attitudes toward science compared to those in Singapore, Chinese-Taipei, Hong Kong, and Japan. In order to achieve these purposes, we analyzed students' survey data on self-confidence in science, interests in science, external motivation for science, and career preference for science collected from TIMSS 1995, TIMSS 1999, and TIMSS 2003. Korean students' interests in science and external motivation for science reduced in TIMSS 1999 and increased again in TIMSS 2003. The amount of change was greater in interests in science. On the other hand, self-confidence in science and career preference for science consistently declined from TIMSS 1995 to TIMSS 2003. Self-confidence in science among boys and girls was similar in TIMSS 1995 and 1999. But self-confidence of girls in science declined rapidly from TIMSS 1999 to 2003, while self-confidence of boys in science remained almost the same. Trends of interests in science were similar between boys and girls; they declined in TIMSS 1999 and increased again in TIMSS 2003. External motivation for science of both boys and girls increased, and the increase among girls was greater. The percentage of boys who wanted to have a job using science consistently declined from TIMSS 1999 to TIMSS 2003, while the percentage of girls declined in TIMSS 1999 and increased in TIMSS 2003 again. The results from an international comparison with other Asian countries having similar cultures showed that Korean students' self-confidence in science, career preference for science of middle school students was the lowest.

• Journal of the Korean Society of Food Culture
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• v.3 no.1
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• pp.67-76
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• 1988

With a view to making comparative study and promoting the interchange of food culture between Korea and Japan, a sensory test was given to 60 female college students (30 Koreans and as many Japanese) in order to find out differences in preference of various teas between the two nations. The findings are as follows: 1. The correlation between each specific tea and total evaluation: Significant level of high positive correlation was indicated in case of color, taste, and aftertaste by both Koreans and Japanese. In case of odor, and flavor the Koreans indicated insignificant level of nought, and the Japanese significant level of high negative correlation one. In sweetness and total evaluation the Koreans indicated positive correlation and the Japanese insignificant level of nought. 2. Comparison of preference of various teas by the Koreans and the Japanese 1) Ginseng tea A and Ginseng tea B As to Ginseng tea A and Ginseng tea B the Koreans liked odor best while the Japanese liked flavor best. In general preference the Koreans liked them better than the Japanese, and both groups indicated significant level (p <.001). 2) Black tea A: As to Black tea A the Koreans liked odor best while the Japanese taste, and in general preference the Japanese liked them better than the Koreans and both groups indicated significant level (p <.001). 3) Black tea B. As to Black tea B the Koreans liked odor best while the Japanese color, and in general preference the Japanese liked them better than the Korean and both groups indicated significant level (p <.01). 4) Coffee A. The Koreans liked odor best while the Japanese flavor, and neither of the groups indicated significant level (p <.05). 5) Coffee B. The Koreans liked color best while the Japanese flavor, and neither of the groups indicated significant level (p <.05). 6) Green tea A and Green tea B. As to Green tea A and Green tea B, the Koreans liked odor best while the Japanese taste. In general preference the Japanese liked them better than the Koreans, both indicated significant level (p <.001). 7) Malcha (a kind of traditional Green tea) Both groups liked flavor best, in general preference the Japanese liked it better than the Koreans, and both groups indicated significant level (p <.001).

• International Area Studies Review
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• v.14 no.1
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• pp.55-76
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• 2010

This paper analyses interaction between yen/dollar exchange rates and NIKKEI index using bivariate GJR-GARCH(1,1) model. The data employed for the study is daily data series for the period of Jan. 4, 1995 through Aug. 30, 2009. One of main findings is that market inefficiency appears in the periods of financial crisis. Second, the volatility of exchange rates and stock returns has more increased in the wake of the volatility shock of the previous period during financial crisis than during non-financial crisis. Third, interestingly, the asymmetric volatility shock by bad news in those markets is bigger in financial crisis period than in non financial crisis. Fourth, in the period of current global financial crisis triggered by subprime mortgage crisis in U.S, volatility shock at the previous period is bigger than that of Asian financial crisis that happened in 1997. Lastly, the correlation between both returns of exchange rates and stock prices turns up positive according to the empirical estimation. This result may come from the fact that Japanese stock market does not have much attraction for international financial investment compared to stock markets of neighbouring countries like China, Korea and so on, while real sector's contribution to the economy is considered more importantly.

• Journal of Life Science
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• v.24 no.6
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• pp.655-663
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• 2014

Woosul (Achyranthis radix), a widely used material in food and oriental medicinal industry, has different origins of plant species in Korea, Japan and China. In Korea, woosul is designated as the radix of Achyranthes japonica Nakai (AJN) and Achyranthes bidentata Blume (ABB) in the regulation of The Korean Pharmacopoeia. However, the comparative study of hot water (HW) extracts between AJN and ABB is still rudimentary. In this study, HW extracts and its subsequent organic solvent fractions of AJB and ABB were prepared, and their in-vitro antimicrobial, antioxidant and anti-diabetes activities were evaluated. The HW extract of ABB has higher sugars and polyphenol compounds, and higher lightness and lower yellowness compared than those of AJN. Analysis of biological activities showed that the ethylacetate (EA) fraction of AJN and n-hexane fraction of ABB have antibacterial activities, and the EA fractions of AJN and ABB has strong antioxidation activities determined by radical scavenging activity and reducing power. In anti-diabetes activity assay, the EA fractions of AJN and ABB showed ${\alpha}$-amylase inhibitory activities, while the butanol fractions of AJN and ABB showed ${\alpha}$-glucosidase inhibitory activities. Our results suggest that the HW extracts of AJB and ABB have different components and extraction yields, and their subsequent fractions have different biological activity. Therefore it was concluded that the EA fraction of AJN is appropriate to develop as natural medicine, and the HW extract of AJN is suitable to woosul-tea or woosul-sikhye production.

• Journal of the Optical Society of Korea
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• v.14 no.3
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• pp.215-220
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• 2010

Aerosol observation with Raman LIDAR in NIES (National Institute for Environmental Studies, Japan) LIDAR network was conducted from 17 April to 12 June 2008 over Beijing, China. The aerosol optical properties derived from Raman LIDAR were compared with the retrieved data from sun photometer and sky radiometer observations in the Aerosol Robotic Network (AERONET). The comparison provided the complete knowledge of aerosol optical and physical properties in Beijing, especially in pollution and Asian dust events. The averaged aerosol optical depth (AOD) at 675 nm was 0.81 and the Angstrom exponent between 440 nm and 675 nm was 0.99 during experiment. The LIDAR derived AOD at 532 nm in the planetary boundary layer (PBL) was 0.48, which implied that half of the total AOD was contributed by the aerosol in PBL. The corresponding averaged LIDAR ratio and total depolarization ratio (TDR) were 48.5sr and 8.1%. The negative correlation between LIDAR ratio and TDR indicated the LIDAR ratio decreased with aerosol size because of the high TDR associated with nonspherical and large aerosols. The typical volume size distribution of the aerosol clearly demonstrated that the coarse mode radius located near 3 ${\mu}m$ in dust case, a bi-mode with fine particle centered at 0.2 ${\mu}m$ and coarse particle at 2 ${\mu}m$ was the characteristic size distribution in the pollution and clean cases. The different size distributions of aerosol resulted in its different optical properties. The retrieved LIDAR ratio and TDR were 41.1sr and 19.5% for a dust event, 53.8sr and 6.6% for a pollution event as well as 57.3sr and 7.2% for a clean event. In conjunction with the observed surface wind field near the LIDAR site, most of the pollution aerosols were produced locally or transported from the southeast of Beijing, whereas the dust aerosols associated with the clean air mass were transported by the northwesterly or southwesterly winds.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.81.2-81.2
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• 2012

To fabricate a metal mold for injection molding, hot-embossing and imprinting process, mechanical machining, electro discharge machining (EDM), electrochemical machining (ECM), laser process and wet etching ($FeCl_3$ process) have been widely used. However it is hard to get precise structure with these processes. Electrochemical etching has been also employed to fabricate a micro structure in metal mold. A through mask electrochemical micro machining (TMEMM) is one of the electrochemical etching processes which can obtain finely precise structure. In this process, many parameters such as current density, process time, temperature of electrolyte and distance between electrodes should be controlled. Therefore, it is difficult to predict the result because it has low reliability and reproducibility. To improve it, we investigated this process numerically and experimentally. To search the relation between processing parameters and the results, we used finite element simulation and the commercial finite element method (FEM) software ANSYS was used to analyze the electric field. In this study, it was supposed that the anodic dissolution process is predicted depending on the current density which is one of major parameters with finite element method. In experiment, we used stainless steel (SS304) substrate with various sized square and circular array patterns as an anode and copper (Cu) plate as a cathode. A mixture of $H_2SO_4$, $H_3PO_4$ and DIW was used as an electrolyte. After electrochemical etching process, we compared the results of experiment and simulation. As a result, we got the current distribution in the electrolyte and line profile of current density of the patterns from simulation. And etching profile and surface morphologies were characterized by 3D-profiler(${\mu}$-surf, Nanofocus, Germany) and FE-SEM(S-4800, Hitachi, Japan) measurement. From comparison of these data, it was confirmed that current distribution and line profile of the patterns from simulation are similar to surface morphology and etching profile of the sample from the process, respectively. Then we concluded that current density is more concentrated at the edge of pattern and the depth of etched area is proportional to current density.

• The Korean Journal of Applied Statistics
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• v.31 no.4
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• pp.427-446
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• 2018

Korea will have a super-aged society within only 30 years according to the United Nations' definition of an aging society and the statistics on Korea's Population projections (2016), indicates that Korea has the fastest ageing speed in the world. There is a lack of data on long-term time-series data on death as related to pension and welfare policies compared to the rapid rate of aging. This paper estimates life expectancy over 245 years (from 1955 to 2200) through past and future forecasts as well as compares the expected life expectancy of the synthetic cohort and the real cohort. In addition, an international comparisons were made to understand the level of aging in Korea. Estimates of the back-projection period were compared with previous studies and the LC model to improve accuracy and objectivity. In addition, the predictions after 2016 reflected the declined mortality rate effect of Korea using the LC-ER model. The results showed an increase in life expectancy of about 30 years over 60 years (1955-2015) with an expected life expectancy of the real cohort over the second century (1955-2155) higher than the synthetic cohort. The comparative advantage of life expectancy of real cohorts was confirmed to be a common trend among comparative countries. In addition, Japan and Korea have a higher life expectancy and starting from 85 to 90 years old, all comparative countries show that the growth rate for the life expectancy of synthetic and real cohorts is less than previous years.

• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.11-20
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• 2016

Objective: This study aimed to compare biomechanical data between elite and beginner cyclists during cycle pedaling by performing a comparative analysis and to provide quantitative data for both pedaling performance enhancement and injury prevention. Methods: The subjects of this study included 5 elite cyclists (age: $18{\pm}0years$, body mass: $64.8{\pm}9.52kg$, height: $173.0{\pm}4.80cm$) and 5 amateur cyclists (age: $20{\pm}0years$, mass: $66.6{\pm}2.36kg$, height: $175.6{\pm}1.95cm$). The subjects pedaled on a stationary bicycle mounted on rollers of the same gear (front: 50 T and rear: 17 T = 2.94) and cadence of 90. The saddle height was adjusted to fit the body of each subject, and all the subjects wore shoes with cleats. In order to obtain kinematic data, 4 cameras (GR-HD1KR, JVC, Japan) were installed and set at 60 frames/sec. An electromyography (EMG) system (Telemyo 2400T, Noraxon, USA) was used to measure muscle activation. Eight sets of data from both the left and right lower extremities were obtained from 4 muscles (vastus medialis oblique [VMO], vastus lateralis oblique [VLO], and semitendinosus [Semitend], and lateral gastrocnemius [Gastro]) bilaterally by using a sampling frequency of 1,500 Hz. Five sets of events ($0^{\circ}$, $90^{\circ}$, $180^{\circ}$, $270^{\circ}$, and $360^{\circ}$) and 4 phases (P1, P2, P3, and P4) were set up for the data analysis. Imaging data were analyzed for kinematic factors by using the Kwon3D XP computer software (Visol, Korea). MyoResearch XP Master Edition (Noraxon) was used for filtering and processing EMG signals. Results: The angular velocity at $360^{\circ}$ from the feet was higher in the amateur cyclists, but accelerations at $90^{\circ}$ and $180^{\circ}$ were higher in the elite cyclists. The amateur cyclists had greater joint angles at $270^{\circ}$ from the ankle and wider knee joint distance at $0^{\circ}$, $180^{\circ}$, and $360^{\circ}$ than the elite cyclists. The EMG measurements showed significant differences between P2 and P4 from both the right VLO and Semitend. Conclusion: This study showed that lower body movements appeared to be different according to the level of cycle pedaling experience. This finding may be used to improve pedaling performance and prevent injuries among cyclists.