• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.49-59
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• 2008

The effects of design parameters on the pellet transport rate in the ejector system which is widely used in the production processes of automotive parts were investigated experimentally. The primary nozzle geometry, the area ratio (R) of nozzle exit cross-sectional area to mixing chamber cross-sectional area and the distance (S) from primary nozzle exit to mixing chamber entrance were considered as the design parameters. The area ratios of the primary nozzle were varied from R=0.10 to R=0.25, 0.30, 0.40 and 0.55. The primary nozzle was positioned at the non-dimensional distance (S/D) of 1.30, 1.87, 2.44, 3.00 and 3.75, normalized using the mixing chamber diameter (D). The design parameters were determined to run with high efficiency by measuring the pellets transport rate. The geometry and the area ratio (R) of the primary nozzle had an effect on the pellet transport rate of the ejector system, and the area ratio of R=0.3 was carefully selected after taking the minimum fluidization velocity and transport rate of applied pellets into account. The higher pellet transport rate with the variation of the distance (S/D) was observed at S/D of 2.44.

• Journal of Broadcast Engineering
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• v.27 no.1
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• pp.91-103
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• 2022

Determination of sound source characteristics such as: sound volume, direction and distance to the source is one of the important techniques for unmanned systems like autonomous vehicles, robot systems and AI speakers. There are multiple methods of determining the direction and distance to the sound source, e.g., using a radar, a rider, an ultrasonic wave and a RF signal with a sound. These methods require the transmission of signals and cannot accurately identify sound sources generated in the obstructed region due to obstacles. In this paper, we have implemented and evaluated a method of detecting and identifying the sound in the audible frequency band by a method of recognizing the volume, direction, and distance to the sound source that is generated in the periphery including the invisible region. A cross-shaped based sound source recognition algorithm, which is mainly used for identifying a sound source, can measure the volume and locate the direction of the sound source, but the method has a problem with "blind spots". In addition, a serious limitation for this type of algorithm is lack of capability to determine the distance to the sound source. In order to overcome the limitations of this existing method, we propose a QRAS-based algorithm that uses rectangular-shaped technology. This method can determine the volume, direction, and distance to the sound source, which is an improvement over the cross-shaped based algorithm. The QRAS-based algorithm for the OSSD uses 6 AITDs derived from four microphones which are deployed in a rectangular-shaped configuration. The QRAS-based algorithm can solve existing problems of the cross-shaped based algorithms like blind spots, and it can determine the distance to the sound source. Experiments have demonstrated that the proposed QRAS-based algorithm for OSSD can reliably determine sound volume along with direction and distance to the sound source, which avoiding blind spots.

• Journal of Environmental Impact Assessment
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• v.21 no.2
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• pp.289-296
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• 2012

The shock vibration such as machine vibration, blasting vibration etc. has effect on nearby structure as well as human body. The purpose of this study is to predict allowable limit distance of vibration about human body. First of all, vibration velocity such as PPV, PVS was measured by shock vibration experiment, and vibration level was calculated by conversion formula of vibration velocity. And then, allowable limit distance was analyzed by converted vibration level. The results are as follows : Firstly, the correlation coefficient of converted vibration level was over R=0.94, and vibration level caused by PVS was usually represented to high curve line. Secondly, the cross point of vibration level between ground and concrete condition was represented to 66.68dB(V), and allowable limit distance was represented to difference over three times when vibration regulation was raised from 65dB(V) to 80dB(V).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.4
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• pp.280-293
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• 2005

In this study, a model to calculate the expected total construction cost has been developed by combining a model to calculate the sliding distance of a caisson of a vertical breakwater and a model to calculate the rehabilitation cost of a caisson. The optimal cross-section of a caisson of a vertical breakwater is defined as the cross-section that requires a minimum expected total construction cost within the allowable limit of caisson sliding. Two allowable limits are considered: 0.1 m of the expected sliding distance during the lifetime of the breakwater and 0.1 of the probability that the cumulative sliding distance during the lifetime of the breakwater is greater than 0.3 m. A discount rate has also been introduced to convert the future rehabilitation cost to the present value. The introduction of the discount rate reduces the expected total construction cost for the caissons designed for shorter return periods due to frequent rehabilitations. The present design method requires a smaller cross-section than the conventional deterministic method in shallow water depths, enabling us to design a caisson more economically. On the other hand, the above-mentioned allowable limits of caisson sliding show similar results for smaller water depths, while, for larger depths, the former requires a larger cross-section than the latter.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.6
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• pp.495-507
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• 2009

The expected sliding distance for the lifetime of a caisson breakwater has a limitation to be used as the stability criterion of the breakwater. Since the expected sliding distance is calculated as the mean of simulated sliding distances for the lifetime, there is possibility for the actual sliding distance to exceed the expected sliding distance. To overcome this problem, the exceedance probability of the allowable sliding distance is used to assess the stability of sliding. Latin Hypercube sampling and Crude Monte Carlo simulation were used to calculate the exceedance probability. The doubly-truncated normal distribution was considered to complement the physical disadvantage of the normal distribution as the random variable distribution. In the case of using the normal distribution, the cross-sections of Okgye, Hwasun, and Donghae NI before reinforcement were found to be unstable in all the limit states. On the other hand, when applying the doubly-truncated normal distribution, the cross-sections of Hwasun and Donghae NI before reinforcement were evaluated to be unstable in the repairable limit state and all the limit states, respectively. Finally, the shortcoming of the expected sliding distance as the stability criterion was investigated, and we reasonably assessed the stability of sliding of caissons by using the exceedance probability of allowable sliding distance for the caisson breakwaters in Korea.

• Restorative Dentistry and Endodontics
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• v.31 no.2
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• pp.96-102
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• 2006

There are various factors affecting the fracture of NiTi rotary files. This study was performed to evaluate the effect of cross sectional area, pecking motion and pecking distance on the cyclic fatigue fracture of different NiTi files. Five different NiTi $files-Profile^{(R)}$ (Maillefer, Ballaigue, Switzerland), $ProTaper^{TM}$(Maillefer, Ballaigue, Switzerland), $K3^{(R)}$ (SybronEndo. Orange, CA) , Hero $642^{(R)}$ (Micro-mega, Besancon, France), Hero $Shaper^{(R)}$ (Micro-mega, Besancon, France)-were used. Each file was embedded in temporary resin, sectioned horizontally and observed with scanning electron microscope. The ratio of cross-sectional area to the circumscribed circle was calculated. Special device was fabricated to simulate the cyclic fatigue fracture of NiTi file in the curved canal,. On this device, NiTi files were rotated (300rpm) with different pecking distances (3 mm or 6 mm) and with different motions (static motion or dynamic pecking motion) . Time until fracture occurs was measured. The results demonstrated that cross-sectional area didn't have any effect on the time of file fracture. Among the files, $Profile^{(R)}$ took the longest time to be fractured. Between the pecking motions, dynamic motion took the longer time to be fractured than static motion. There was no significant difference between the pecking distances with dynamic motion, however with static motion, the longer time was taken at 3mm distance. In this study, we could suggest that dynamic pecking motion would lengthen the time for NiTi file to be fractured from cyclic fatigue.

• 한국경영정보학회:학술대회논문집
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• 2007.11a
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• pp.565-570
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• 2007

With e-commerce becoming international, understanding the effects of national culture in consumer acceptance of e-commerce is required. This study examines consumer e-commerce acceptance in Korea and China. The research model consisting of perceived usefulness, perceived ease of use, trust and perceived risk was proposed, and the hypotheses based on Hofstede's cultural dimensions of power distance, individualism/collectivism, masculinity/femininity, uncertainty avoidance and long-term orientation, were established. The results show that perceived usefulness contributes less to consumer acceptance of e-commerce in China than it does in Korea. In addition, perceived ease of use contributes more to consumer acceptance of e-commerce in China. Trust contributes significantly to consumer acceptance of e-commerce in both countries, but perceived risk didn't influence consumer acceptance of e-commerce in either country. The contribution of this study is to provide strategic insights for successfully managing cross-cultural e-commerce.

• Journal of the Korean Wood Science and Technology
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• v.13 no.2
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• pp.35-44
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• 1985

The purposes of this study were, first, to investigate retention levels of toxic elements and oxide individual plies for each panel and, second, to examine disproportioning of individual toxic elements Thirty five water gum plywood panels were treated with a copper-chromium-arsenic preservative (CCA) by the soaking process as the treament time were applied. Such individual plies at a distance of 2.5cm, 7.5cm from the edge were assayed for CuO, $CrO_3$, and $As_2O_5$ on the basis of copper, chromium and arsenic content by Atomic Absorption Spectrophotometry. In these experiments, 12mm thickness plywood panels made of water gum, which were selling, were selected for the preservative treatment. Treating solutions were prepared for 10%, dilute solution of copper-chromium-arsenic preservative and then 1, 3, 6, 12 and 24 hours soaking trements in CCA preservative were applied. The results obtained are as follows: 1. The retention of total oxide in the face and back plies (1+7) retained more than the retention of total oxide in the other plies. The total oxide retention for the individual plies except the face and back plies (1+7) was showed in the following orders; cross plies (3+5), cross plies (2+6), core ply (4). 2. The retentions of total oxide increased as the increase of treatment time. The CCA treated plywood retained high levels of total oxide retention in the face and back plies (1+7). 3. All the retentions in the face and back plies (1+7) is over 5Kg/$m^3$, New Zealand Timber Preservation Standards Specification, and after 6 hours, the retentions in the cross plies (3+5) is over 4. The relative penetration of copper, chromium, and arsenic were not affected by the treatment time. The proportion of arsenic decreased in relation to both copper and chromium and the proportion of copper increased in relation to both chromium and arsenic. 5. A disproportioning of copper, chromium occurred with longer distance from edge, and with longer distance from edge the leachability resistance of CCA treated specimens decreased. After 6 hours (soaking time), the proportion of active elements at a distance of 2.5cm from the edge was consistent. And after 24 hours-soaking, the proportion of active elements at a distance of 7.5cm from the edge was consistent.

• Journal of Korean Academy of Nursing Administration
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• v.20 no.5
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• pp.505-513
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• 2014

Purpose: The purpose of this study was to identify factors affecting the social distance between minority groups and nursing cadets. Methods: A cross-sectional survey design was used. A questionnaire was distributed to the entire Armed Forces Nursing Academy cadets. Data from 273 nursing cadets were analyzed using t-test, ANOVA, Pearson correlation coefficients and Stepwise multiple regression. Results: Social distance had positive correlations with collective identity (r=.28) and multiculturalism (r=.37). A negative correlation was found between social distance and perceived threat (r=-.38). Perceived threat, multiculturalism, collective identity, and frequency of contact with minorities were identified as factors affecting the social distance. The model explained 24% of the variables. Conclusion: To effectively respond to the minority groups' nursing needs in the army, educational programs which help to reduce the perceived threat, to strengthen multiculturalism, and to establish a healthy collective identity of nursing cadets need to be developed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.4
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• pp.464-469
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• 2015

This study was carried out to find relationships of genetic distance and heterosis expression degree in the developed CNU waxy corn lines. The used material were developed in Corn Breeding Laboratory, Coll. of Agri. & Life Sci., CNU. Total 10 primers used for SSR maker analysis. In genetic distance, the used lines divided into four groups; A group has two lines, B group has one line, C group has ten lines and D group has eleven lines, respectively. Among used lines, CNU427 and CNU588 were very closed as a 74, while CNU451 and CNU429 were remote as a 40 inbred coefficient, respectively. While heterosis degree were very variable not only hybrids but also cross parents. Average heterosis of most cross-parent was high in plant height, ear height, flowering day and ear length. Especially, CNU H09-23 hybrid was high as 79.4% than other hybrids. Here, we gained the fact has closely relationship between genetic distance and heterosis.