• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.5
• /
• pp.451-457
• /
• 2011

The main objective of this study is to investigate the variation in the ignition characteristics of coals as a function of moisture content in a laminar flow reactor (LFR) equipped with a fuel moisture micro-supplier designed by the Pusan Clean Coal Center. The volatile ignition position and time were observed experimentally when a pulverized coal with moisture was fed into the LFR under burning conditions similar to those at the exit of the pulverizer and real boiler. The reaction-zone temperature along the centerline of the reactor was measured with a $70-{\mu}m$, R-type thermocouple. For different moisture contents, the volatile ignition position was determined based on an average of 15 to 20 images captured by a CCD camera using a proprietary image-processing technique. The reaction zone decreased proportionally as a function of the moisture content. As the moisture content increased, the volatile ignition positions were 2.92, 3.36, 3.96, and 4.65 mm corresponding to ignition times of 1.46, 1.68, 2.00, and 2.33 ms, respectively. These results indicate that the ignition position and time increased exponentially. We also calculated the ignition-delay time derived from the adiabatic thermal explosion. It showed a trend that was similar to that of the experimental data.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.3
• /
• pp.209-215
• /
• 2003

This experiment was conducted to study the varietal and ecological difference of rice in heading date by night illumination. The degree of delay in heading date and days from heading initiation to full heading (DHIF) of rice were in the order of mid-late maturing cultivars (MLC)＞ medium maturing cultivars (MEC) ＞early maturing cultivars (EAC) ＞very early maturing cultivars (VEC). However, the MEC showed significant variation in days to heading; Kwanganbyeo delayed significantly, but Ansanbyeo did not. The comparative sensitivity of different rice ecotypes per lux in delayed heading was 0.09-0.10, 0.14-0.26, 0.16-0.58, and 0.35-0.54 day in VEC, EAC, MEC, and MLC, respectively; the shortest ion Odaebyeo (0.09 day), moderate in Daeanbyeo (0.35 day), and the longest in Kwanganbyeo (0.58 day). Difference of DHFI was 0.-1 day in VEC, -l-2 days in EAC, 0-l6 days in MEC and 6-18 days in MLC under 50-70 lux compared to 2 lux; Daejinbyeo (-1 day), Hwaseongbyeo (6 days), Chucheongbyeo (9 days), Kwanganbyeo (16 days), and Ilpumbyeo (18 days).

• Journal of the Korean Society for information Management
• /
• v.37 no.2
• /
• pp.47-69
• /
• 2020

This research provides a quantitative analysis on research articles published in PLoS ONE, a multidisciplinary open access journal, by authors affiliated with Korean institutions. Korean authors published more than 6,500 research ariticles in the mega journal between 2006 and 2019. Korea is ranked the top 11th place in terms of article publishing in the journal. Most articles by Korean authors are concentrated in the biomedical fields. In recent years, the overall production of PLoS ONE has decreased as authors migrated to competing mega journals such as Scientific Reports and BMJ Open. The change might have been affected in part by the delay in the review period and the dropping impact factor score. The open access share of the Korean PLoS ONE authors of more than 10 articles hovers around 30%. However, there is a significant variation among researchers reaching up to 50% discrepancies. Among altmetrics provided by PLoS ONE, the saves are highly correlated with the views and the citations. On the contrary, the shares show low correlation with other use metrics. A follow up, survey questionnarie based research involving researchers who have published in PLoS ONE is planned in order to investigate author motivation and experience in the review process.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.2
• /
• pp.121-128
• /
• 2003

Acoustic Echo Cancellation(m) is very active research topic having many applications like teleconference and hands-free communication and it employs Double Talk Detector(DTD) to indicate whether the near-end speaker is active or not. However. the DTD is very sensitive to the variation of acoustical environment and it sometimes provides wrong information about the near-end speaker. In this paper, we are focusing on the development of robust DTD algorithm which is a basic building block for reliable AEC system. The proposed AEC system consists of delayless subband AEC and narrow-band DTD. Delayless subband AEC has proven to have excellent performance of echo cancellation with a low complexity and high convergence speed. In addition, it solves the signal delay problem in the existing subband AEC. On the other hand, the proposed narrowband DTD is operating on low frequency subband. It can take most advantages from the narrow subband such as a low computational complexity due to the down-sampling and the reliable DTD decision making procedure because of the low-frequency nature of the subband signal. From the simulation results of the proposed narrowband DTD and wideband DTD, we confirm that the proposed DTD outperforms the wideband DTD in a sense of removing possible false decision making about the near-end speaker activity.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.8
• /
• pp.34-41
• /
• 2017

Vehicle to Infrastructure(V2I) communication means the technology between the vehicle and the roadside unit to provide the Intelligent Transportation Systems(ITS) and Telematic services. The vehicle collects information about the probe data through the evolved Node B(eNodeB) and after that eNodeB provides road conditions or traffic information to the vehicle. To provide these V2I communication services, we need a link adaptation technology that enables reliable and higher transmission rate. The receiver transmits the estimated Channel State Information(CSI) to transmitter, which uses this information to enable the link adaptation. However, due to the rapid channel variation caused by vehicle speed and the processing delay between the layers, the estimated CSI quickly becomes outdated. For this reason, channel interpolation and prediction scheme are needed to achieve link adaptation in V2I communication system. We propose the Advanced Discrete Prolate Spheroidal Sequence(ADPSS) channel interpolation and prediction scheme. The proposed scheme creates an orthonomal basis, and uses a correlation matrix to interpolate and predict channel. Also, smoothing is applied to frequency domain for noise removal. Simulation results show that the proposed scheme outperforms conventional schemes with the high speed and low speed vehicle in the freeway and urban environment.

• Geophysics and Geophysical Exploration
• /
• v.14 no.4
• /
• pp.305-315
• /
• 2011

A total of 864 measurements for P- and S- wave velocity of acrylic and stainless steel core samples have been performed with respect to their lengths and axial load applied. S-wave velocity measurement was much harder than P-wave velocity, so that it showed higher deviation in measured S-wave velocity with respect to repeated measurement, length of the cores, and the axial load applied. Velocity measurements for acrylic cores showed more stable and less than half of the variation between the measurements than the stainless steel cores. This seems to be come from better coupling between the transducers and acrylic cores than stainless cores, and from larger value of the first arrival time in a similar system noise environments. From the analysis of the 864 measurements, it is recommended that the length of the core be 60 ~ 90 mm, axial load between 20 kg (27.7 $N/cm^2$) and 30 kg (41.6 $N/cm^2$) for measurement of wave velocity of the acrylic and stainless steel cores. Especially for measuring S-wave velocity of stainless steel core, core length should be less than 50 mm, otherwise it will be affected by mode conversion or others. These results can be used in measurement and correction for system delay in wave velocity measurement for rock cores.

• Korean Journal of Construction Engineering and Management
• /
• v.16 no.5
• /
• pp.114-122
• /
• 2015

Real estate development requires significant amount of capital investment. The project duration has been increased according to its enlarged size. For this reason, cost overrun and time delay are important risk factors that should be managed properly. As a method to hedge the risk, varoius real option methods have been presented. However, conventional project value assesment methods such as NPV(Net Present Value) have weakness to support decision making by reflecting dynamic situations in terms of variation of cost and time. Furthermore, the decision making process is serious of actions rather than discrete event. The purpose of this paper is to present a multiple real option valuation method to overcome the deterministic aspect of real option presented in previous research and practice. The method is developed as following: firstly, to select the model that can be applied in the real estate development project through a survey from previous literature on real options analysis; secondly, to apply data from office development case in order to verify the model by applying conventional real option and multiple real option valuation. According to analysis result, multiple real option provides enhanced values comparing to NPV and single real option.

• Korean Journal of Environment and Ecology
• /
• v.27 no.6
• /
• pp.666-675
• /
• 2013

This research was carried out from March 2009 to July 2012 to explicate the height change based breeding-ecological characteristics of Titmice that were breeding in the artificial nests installed in the Halla Mountain. The first egg-laying day was delayed as the height of the area under investigation increased, and it turned out that the decrease in temperature due to the elevated height had influence on that delay (p<0.05). Generalizing the annual results of the analyses, we see that there was no significant correlation occurring between the average temperatures and egg-laying days in the breeding season (April~June) (p>0.05). The rate of artificial nest use was not different among areas and among year, but between the species, Parus major and Parus varius. There were differences in clutch sizes among species (p>0.05), but no differences in heights and years (p<0.05). The hatching-, fledging-, and breeding-success rates were 67.3%, 99.5%, and 67.0% respectively in 2011, and 71.3%, 96.8%, 69.0% respectively in 2012, from which we can tell that the fledging-success rate was high but the hatching- and breeding-success rates were similar. Though we confirm that temperature changes due to height differences had influence on breeding periods, but we cannot identify a significant correlation with other breeding-ecological characteristics. Thus, in order to more precisely explicate the influence of temperature changes due to heights on Titmice's breeding, long-term research is needed in terms of the investigation of microclimatic factors and food resource.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.2
• /
• pp.151-160
• /
• 1997

In this paper, we have carried out the DS/CDMA with a suppressed pilot channel, which is used in receiving coherently with Rake diversity and in synchronizing the chip timing, in the mobile satellite communication. Also, we have investigated the envelope variation of a shadowed Rician fading simulator, and analyzed the error performences of DS/CDMA in the mobile satellite communication. The results showed that the error performance in the Heavy shadowing environment might be degraded more than in the Rayleigh fading environment since the fading envelopes in the former environment are varied randomly compared with those in the latter environment. And the performence of DS/CDMA system could be improved about 10 dB compared with that of narrowband QPSK system. In conclusion, DS/CDMA with a suppressed pilot channel had the best performance in the case of the suppressed pilot channel to transmission power ratio $\beta$=-8 dB, the number of complex delay profiles $N_{profile}$=32, and using these values, the error performance of DS/CDMA in Light shadowing environment was identical to the ideal QPSK error performance.

• Progress in Medical Physics
• /
• v.12 no.1
• /
• pp.9-17
• /
• 2001

The prior purpose of this study is to introduce a optical biopsy and evaluate whether the optical biopsy, real-time, non-invasive technique, is a reliable tool to assess response to radiotherapy Four healthy volunteers, and four patients with inflammatory conditions of the oral cavity participated on the study. was obtained from each person enrolled in the study. Using FastEEM(Ercited Emission Matrix) as a optical biopsy tool, normal and tumor spectra are taken from the normal and the tumor regions. And then second optical biopsy are taken from the tumor regions in 4 patients with time delay at 7days.. Using a diagnostic algorithm, made by Gillenwater based on spectra excited at 337nm The Optical Biopsy turned out to be more suited for tumor diagnostic resulting in significant difference fluorescence spectra. The fluorescence intensity of cancerous tissue showed a higher position. The second fluorescence intensity of optical biopsy of cancerous oral tissue has more smaller than the first result. I conclude that optical biopsy, which technique don't need to remove tissue sample from body, and is a real time , and non-invasive measurement is a reliable tool to access to radiotherapy because FastEEM can do measure the variation of the tissue composition chemical, biological, and morphological after radiotherapy. Based on the fluorescence spectrum are taken from the optical biopsy in normal and tumor spectra as well as tumor spectra after 7days.