• Journal of the Ergonomics Society of Korea
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• v.27 no.4
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• pp.95-101
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• 2008

This research is to develop PPG filtering method for respiration measurement in U-Health Care system. Respiration rate was determined by filtering PPG and analyzing its spectrum. Optimal filter of PPG has been selected to get respiration by testing 120 sets of experiment data using 700 filtering cases. As a result, 2nd order Bessel-filter that used band-pass cutoff frequency at 0.175~0.4Hz with second order was good at developing respiration signal. Respiration signal in time domain could be continuously analyzed by converting frequency domain using spectrum analysis. 24 seconds has been found to be optimal time duration of collecting PPG data for determining respiration. Therefore, this study was successful of getting not only heart activity but also respiration by only PPG. Minimal invasive measurement obtaining multi-bio information by one sensor can be expected to apply to U-Health Care and human computer interaction.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.4
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• pp.271-282
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• 2003

Automotive occupant packaging has been a part of main ergonomics interests, especially, in terms of driver's posture. Previous research on driver's posture has mainly focused on the initial optimal posture for driving sedans. However, customer preferences on cars are shifting from sedans to RV and automobile manufacturing companies seek to understand temporal changes in drivers' posture according to driving environment. So the main aim of this study was to develop a driver's posture measurement system during driving and investigate casual changes due to duration, car type, traffic flow. Four male drivers participated in the experiments during one week. It was shown that considerable changes in their postures were caused with respect to driving environment, which implies that not only static optimal postures but their dynamic changes should be taken into consideration for proper design and evaluation of interior packaging. The research is expected to help packaging designers understand human drivers so as to improve their comfort.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.343-348
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• 2010

Recently, unmanned electric vehicles are increasingly interested among all of the world since they can provide low exhaust gas, high efficiency and high mobility. To exploit their silent maneuver and high mobility, unmanned electric vehicles have been developed since early 1980's for military. However, it is not easy to design and control a power system satisfying operating duration and mobility performance requirements based on various mission profiles for military use under the conditions of limited space and weight. Moreover it is also necessary to prevent over-charge, over-discharge and voltage unbalance between cells of battery to secure high voltage battery which is serially connected with muti-cells. In this paper, we presents power control and optimal management method for the dog-horse robot which adopts a electric power system and suggests a guide-line to manage and control to secure high voltage battery.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.739-744
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• 2008

The method of yeast propagation has an influence on yeast physiology, fermentation ability, flocculation rate, and taste stability of beer. In order to find optimal conditions for propagation, several parameters were investigated in combinations. The bottom brewing yeast grown at $10^{\circ}C$ indicated that a higher flocculation capacity during the $1^{st}$ fermentation. However, the taste stability and the aroma profile were not affected by parameters of propagation investigated. The beer quality was rather affected by storage duration. In addition, a correlation between tasting and chemiluminescence was found at the beer, which was produced using bottom brewing yeast. The propagation at $10-25^{\circ}C$ with addition of zinc ion indicated the best condition to improve fermentation ability, flocculation rate, and filterability for bottom brewing yeast, whereas the propagation at $30^{\circ}C$ with addition of zinc ion showed the best condition to increase fermentation ability for top brewing yeasts.

• Phonetics and Speech Sciences
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• v.13 no.1
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• pp.45-51
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• 2021

End-to-end (E2E) automatic speech recognition (ASR) has achieved promising performance gains with the introduced self-attention network, Transformer. However, due to training time and the number of hyperparameters, finding the optimal hyperparameter set is computationally expensive. This paper investigates the impact of hyperparameters in the Transformer network to answer two questions: which hyperparameter plays a critical role in the task performance and training speed. The Transformer network for training has two encoder and decoder networks combined with Connectionist Temporal Classification (CTC). We have trained the model with Wall Street Journal (WSJ) SI-284 and tested on devl93 and eval92. Seventeen hyperparameters were selected from the ESPnet training configuration, and varying ranges of values were used for experiments. The result shows that "num blocks" and "linear units" hyperparameters in the encoder and decoder networks reduce Word Error Rate (WER) significantly. However, performance gain is more prominent when they are altered in the encoder network. Training duration also linearly increased as "num blocks" and "linear units" hyperparameters' values grow. Based on the experimental results, we collected the optimal values from each hyperparameter and reduced the WER up to 2.9/1.9 from dev93 and eval93 respectively.

• Journal of Marine Bioscience and Biotechnology
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• v.12 no.2
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• pp.115-122
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• 2020

Eisenia bicyclis, a perennial macroalga is a primary producer of in the ocean, It has been identified as a key species that plays a vital role in maintaining the ecosystem stability. Also, it is an important target in marine afforestation projects and useful marine organisms. In addition, E. bicyclis is used as a health food for humans. This study investigated the effect of water temperature, light (photon irradiance), and duration of light (photoperiod) on the growth of gametophytes and young sporophytes of E. bicyclis. The germination and growth of the zoospores of E. bicyclis were examined at five temperatures (5℃, 10℃, 15℃, 20℃ and 25℃), four intensities of photon irradiance (10, 20, 40, and 80 μmol m-2s-1), and photoperiods (14:10 and 10:14 light/dark cycles). The zoospores released from mature plant germinated into the gametophytes under all experimental conditions. The gametophytes were able to grow at water temperature 5℃-25℃ and mature at 10℃-20℃. The optimal range of water temperature for the maturation of the gametophyte was 15℃-20℃. At 25℃, E. bicyclis gametophytes grew rapidly but did not mature. The optimal culture conditions for the growth of young sporophytes grew slowly in low temperature and photon irradiances.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.11
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• pp.4372-4394
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• 2020

The distribution of popular videos incurs a large amount of traffic at the base stations (BS) of networks. Device-to-multi-device (D2MD) communication has emerged an efficient radio access technology for offloading BS traffic in recent years. However, traditional studies have focused on synchronous user requests whereas asynchronous user requests are more common. Hence, offloading BS traffic in case of asynchronous user requests while considering their time-varying characteristics and the quality of experience (QoE) of video request users (VRUs) is a pressing problem. This paper uses social stability (SS) and video loading duration (VLD)-tolerant property to group VRUs and seed users (SUs) to offload BS traffic. We define the average amount of data transmission (AADT) to measure the network's capacity for offloading BS traffic. Based on this, we formulate a time-varying bipartite graph matching optimization problem. We decouple the problem into two subproblems which can be solved separately in terms of time and space. Then, we propose the socially aware D2MD user selection (SA-D2MD-S) algorithm based on finite horizon optimal stopping theory, and propose the SA-D2MD user matching (SA-D2MD-M) algorithm to solve the two subproblems. The results of simulations show that our algorithms outperform prevalent algorithms.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.390-399
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• 2014

The objective of this study was to establish a processing technology for preserved leaves based on the results from the examination of the optimal period and condition for dye-absorbing treatment for Eucalyptus cinerea F. Mull. ex Benth. (silver dollar eucalyptus) being used frequently as plant material for flower design. Cut foliages of E. cinerea with uniformly matured leaves were cut into 20 cm lengths and their lower stem parts were placed in dye solution in growth chambers with different temperatures (10, 20, 30, and $40^{\circ}C$), vapor pressure deficits (VPD; 0.23, 0.70, 1.17, and 1.61 kPa), and photoperiods (0, 6, 12, 24 hours) for 3, 6, 9, and 12 days, and then dried in a room of $20^{\circ}C$ for three days. Lower temperature during preserving dye treatment reduced the changes in leaf color compared with fresh leaves and decreased ${\Delta}E$ value. Especially, high temperature increased red degree (a) and decreased yellow degree (b) due to browning. Lower VPD reduced the change in leaf color compared with fresh leaves and decreased ${\Delta}E$ value. Shorter photoperiod reduced the change in leaf color compared with fresh leaves and decreased ${\Delta}E$ value. The ${\Delta}E$ value increased with increasing absorbing duration under three environmental conditions. The flexibility of stem and leaves after dipped into preserving dye solution and dried for 3 days increased with decreasing temperature, VPD and dipping duration. Therefore, the optimal environment condition for dye treatment was 0.23-0.70 kPa VPD at $10-20^{\circ}C$ in the darkness, and the optimal and economical duration was 3 days. These conditions reduced the speed of water loss by decreasing transpiration, so yellowing or browning by rapid water loss deteriorated the quality of preserved leaves out of these ranges.

• KSBB Journal
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• v.13 no.5
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• pp.502-510
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• 1998

Stabilization of antibody, which is specific to Salmonella typhimurium antigens, present in dry states on membranes was accomplished, and its shelf-life, i.e., duration for maintaining minimum 90% of the initial activity, under optimal conditions was determined. To prepare two major components of an immuno-strip, the antibody was not only immobilized on nitrocellulose membrane surfaces but also placed within the pores of glass fiber membrane after conjugating it with old colloids as signal generator. Among potential stabilizers of the immuno-components, a disaccharide, trehalose, showed a significant protection effect of immunoglobulin structure from thermal energy. Optimal concentrations of trehalose for the respective component were significantly different (8-fold higher for the antibody-gold conjugate than for the immobilized antibody), which probably resulted from distinct densities and configurations of antibody present on the membranes. An additional requirement for the gold conjugate was freeze-drying of this substance such that the conjugate can be readily resolubilized upon contact with aqueous medium. By using the components prepared under optimal conditions, immuno-strips were constructed and exposed to thermal energy. Signals with less than 10% decrease in the intensity were maintained for approximately 21 days at 60$^{\circ}C$. Compared to previous reports, this result represented a 2-year shelf-life at room temperature. it was, however, two times longer if determined from thermal acceleration tests based on the theory of inactivation rate of protein. Such discrepancy between the two estimates could be mainly attributed to errors in accurately controlling temperatures and also to changes in the physical properties of membranes due to a high thermal energy.

• Journal of Mushroom
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• v.12 no.3
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• pp.216-219
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• 2014

Studies were made to optimize the media composition in bag culture and conducted to determine the possibility of artificial cultivation of Auricularia auricula. Sawdust spawn of media composition for optimal growth were found to be oak-sawdust 80%combination of 20% popla-sawdust were the best of the optimal combination. And optimal substrate combination were found to be cotton-seed meal combination of 10% wheat bran 5% mixed were the best of combination. The duration of spawn run period and primordial formation period on bag(1.2 kg) were 50 days and 7 days, respectively. The weight of fruiting body and the yield(100ea, 1.2 kg) of fresh fruit-body were 24 g and 45,000 g, respectively.