• Journal of the Korean Society of Safety
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• v.22 no.6
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• pp.46-54
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• 2007

The purpose of this study was to examines the burning rate of fire retardant treated wood in the cone heater with a one-dimensional integral model. The wood samples used in this study were four species. The species of woods are Redwood, White oak, Douglas fir and Maple. Each sample was nominally 50mm thick and 100mm square. Samples were exposed to a range of incident heat fluxes 10 to $35kW/m^2$ using the cone heater. A one-dimension integral model has been used to predict burning rate, heat of gasification, flame heat fluxes, charring rate and char depth of samples. As a result measurement of mass loss rate, softwoods(Redwood and Douglas fir) has relatively low value than those for hardwoods(White oak and Maple). Average charring rate of woods in case of fire retardant treatment showed reduction effect of 41.29%, 50.00%, 48.18% and 60.82% for Redwood, Douglas fir, White fir and Maple, respectively. Almost all the predictions from integral model showed faster charring than those measured. Average difference between predictions and experimental data was 16%, 9.5% and 11.8% for N, F1 and F2 respectively. Water-soluble fire retardant used in this study find out more effect in hardwood than softwood from the result of measurement of mass loss rate and average charring rate.

• Journal of the Semiconductor & Display Technology
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• v.23 no.2
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• pp.33-37
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• 2024

Recently, wearable virtual reality devices are widely used. These instruments include a 3-axis accelerometer. User's heart rate information in virtual reality contents can be useful for measuring user experience. In this paper, we propose a method to measure the heart rate through a 3-axis accelerometer based on the principle of ballistocardiography without additional sensors. The angular velocity was successively measured in a time series by the 3-axis accelerometer mounted to the head. The frequency of the maximum magnitude is determined as the heart rate through frequency transform and band pass filtering of the time series signal. For verification, the heart rate calculated from photoplethysmography sensors acquired at the same time was compared as ground-truth. In the virtual reality, the user's heart rate information can be extracted without additional heart rate sensor, and the emotional state and fatigue can be measured.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.37-43
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• 2000

In this experimental study we proposed the double dielectric barrier discharge (DDBD) reactor to produce as high an electric field as possible. The experiment are conducted for applied voltage from 15 to 20[kV], $1~4[\ell/min]$ of gas flow rate and 120[Hz] and 240[Hz] of pulse rate. Superposition discharge(SPD) generated in DDBD which combined the surface discharge with the silence discharge was the most effective to reduce the $NO_x$. In the decomposition efficiency per watt, the low pulse rate gave better efficiency than the high pulse rate. However in DeNOx rate, the high pulse rate gave better performance than the low pulse rate. $NO_x$ removal rate and efficiency increased with increasing the applied voltage in all reactors.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.579-585
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• 2008

Numerous experimental investigations on metallic materials and solid polymers have shown that relaxation behavior is nonlinearly dependent on prior strain rate. The stress drops in a constant time interval nonlinearly increase with an increase of prior strain rate. And the relaxed stress associated with the fastest prior strain rate has the smallest stress magnitude at the end of relaxation periods. This paper deals with the performance of three classes of unified constitutive models in predicting the characteristic behaviors of relaxation. The three classes of models are categorized by a rate sensitivity of kinematic hardening rule. The first class uses rate-independent kinematic hardening rule that includes the competing effect of strain hardening and dynamic recovery. In the second class, a stress rate term is incorporated into the rate-independent kinematic hardening rule. The final one uses a rate-dependent format of kinematic hardening rule.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.3
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• pp.79-86
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• 1997

The characteristics of wastewater treatment according to operating condition of indirectly aerated fluidized bed filled with sand media were studied experimentally, and the obtained results were as follows; 1. During be operated under the BOD loading rate, $4.5kg-BOD/m^3{\cdot}day$, effluent SS according to the increase of recirulation velocities was gradually decreased. 2. According to the increase of media concentration, sludge convertion rate was gradually increased. 3. Under the same BOD loading rate, according to the increase of recirulation velocities, F/M ratio was gradually increased, however, sludge convertion rate was greatly decreased. On the other hand, inffluent BOD concentration has not an important effect. 4. Under the constant recirulation velocities, according to the increase of BOD loading rate, sludge convertion rate was gradually increased. 5. Under the same BOD loading rate, according to the increase of recirulation velocities, oxygen consumpion rate of microorgnism was gradually increased.

• Journal of Korean Society of Rural Planning
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• v.25 no.3
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• pp.11-18
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• 2019

It is widely known that agricultural plastic waste incineration by farmers may cause big forest fire or fine dust in rural areas. Hence, how to increase the rate of collection and recycling of the agricultural plastic waste is of concern to policy makers especially for rural environment. The purpose of this study is to find the determinants of the collection rate of agricultural plastic waste. This study used the data from 'Research on Agricultural Waste' by the Korea Environment Corporation from year 2012 to 2015 for 163 regions. This study found that the compensation rate for collection, the frequency of collecting services, and the quality of waste are important to increase the collection rate. And the regions with more elderly and low income people are more likely to have higher collection rate. Finally, the chief producing regions that are specialized in a certain crop shows higher collection rate.

• Journal of Korea Technology Innovation Society
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• v.5 no.1
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• pp.59-71
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• 2002

Risk, or exposure to uncertainty, is an inherent of risk-adjusted discount rate. It is therefore important part factor in the determination of risk-adjusted discount rate. This paper suggests the method to quantify risk and explains the process how to transfer quantified risk into incremental discount rate. The estimates of underlying risks will help determine the size of appropriate risk-adjusted discount rate with logical and scientific way when the technology valuation is made.

• Journal of the Korean Data and Information Science Society
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• v.20 no.4
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• pp.655-660
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• 2009

As the global economic crisis, the Korean foreign exchange market appears unstable with large fluctuations in exchange rate. Inevitably, there is growing attention on price variables such as exchange rate and interest rates and also on corelation between the factors. This is an empirical study on the causality of fluctuation between exchange rate and interest rate in the Korean market under global economic crisis. The fluctuations in won/dollar exchange rate and call rate are described and followed by analysis of lead-lag relationship between the two variables using Cross-correlation function and Granger causality test.

• MALSORI
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• no.64
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• pp.15-37
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• 2007

The purpose of this paper is to examine the change of the times on the transmission rate of broadcast message. In order to find out the research results, I collected past recorded news tapes and selected 22 radio news out from era of Japanese Imperialism, 1950's, 1960's and contemporary age. Next I measured each announcer's reading rate, and compared change on news-reading rate between present and past approximately 50 years ago. The results of study with such procedures and methods are as follows : the average reporting rate of newscasters in each era is different. From these results, we can easily grasp diachronic change in the transmission rate of broadcast message. Namely, the results show us that present announcers read news faster than the group of past era of Japanese Imperialism by 68%.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.668-672
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• 2009

In wireless ad-hoc network, knowing the available bandwidth of the time varying channel is imperative for live video streaming applications. This is because the available bandwidth is varying all the time and strictly limited against the large data size of video streaming. Additionally, adapting the encoding rate to the suitable bit-rate for the network, where an overlarge encoding rate induces congestion loss and playback delay, decreases the loss and delay. While some effective rate controlling methods have been proposed and simulated well like VTP (Video Transport Protocol) [1], implementing to cooperate with the encoder and tuning the parameters are still challenging works. In this paper, we show our result of the implementation experiment of VTP based encoding rate controlling method and then introduce some techniques of our parameter tuning for a video streaming application over wireless environment.