• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4554-4560
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• 2023

Continuous monitoring of radioactive substances over a prolonged duration can yield crucial insights into the levels of radiation exposure through inhalation, both in the vicinity of nuclear facilities and/or general environments. In this study, we evaluated long-term measurements (2012-2022) of gross alpha-beta activities in the air in the vicinity of nuclear facilities and reference site, distribution characteristics of temporal trends and spatial fluctuations, and factors affecting radioactivity levels. The average airborne gross-α (in mBq m^-3) for onsite and off-site were 0.124 and 0.117, respectively, and the average airborne gross-β (in mBq m^-3) measurements were 1.10 and 1.04, respectively. The activity ratio (AR) of gross-α and gross-β were calculated as a ratio of 0.12. The distribution characteristics of gross-α and gross-β activities in this study area are likely influenced by the meteorological factors and variations in airborne PM concentrations rather than the operation of the nuclear facility.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.383-390
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• 2011

In this study, 26 normal subjects were studied to compare the biomechanical Analysis of Lower Limbs on Speed of Nordic Walking. The biomechanical variables were determined by performing three-dimensional gait analysis, and the measurements items were spatial and temporal parameters; vertical ground reaction force; and moments of the hip, knee, and ankle joints. The purpose of this study based on the speed of Nordic Walking to the vertical ground reaction force and joint moments of each were analyzed. Nordic Walking with poles while being whether this weight is reduced to load, not the improvement of muscle activity by identify Nordic walking is to allow efficient. The results of the analysis were follows. The spatial parameters of step length, stride length significantly increased with increase in velocity(p<0.001). The temporal parameters of step time, stride time, the duration of double support use, and the duration of single support use also significantly decreased with increase in velocity(p<0.001), but cadence significantly increased(p<0.01). Analysis of the changes in ground reaction force revealed that vertical ground reaction force significantly increased at the initial contact and the terminal stance and decreased at the mid stance with increase in velocity(p<0.001). Moments of the hip and knee joints significantly in creased with increase in velocity whereas that of the ankle joint did not. Gait analysis revealed that weight-bearing decreased and moments of the hip and knee joints increased with increase in velocity(p<0.01). The results of this study may help people perform Nordic walking efficiently and Nordic walking can be used in the gait training of people with an abnormal gait.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.77-102
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• 1994

Many studies have been made on the masticatory and esthetic effects of prosthodontic treatments, but few on the restoration of pronunciation, especially in complete denture wearers. The purpose of this study is to provide a basis that could be of help to the complete denture wearers' speech adaptation by analyzing the influence of the palatal coverage upon the duration of consonants and vowels with the method of experimental phonetics. For this study, metal plates and resin plates were made for 3 male subjects in their twenties, who have good occlusion, and do not have speech and hearing disorders. Then 8 Korean consonants and 4 Korean vowels were selected, systemically considering phonetic variants such as the place and manner of articulation, lenis/fortis, mutual effect of each phoneme, etc. They were combined into meaningless tested words in the form of /VCV/, and were included in the carrier sentences. Each informant uttered the sentences 1) without the plate, 2) with the metal plate, 3) with the resin plate. The recorded data were analyzed through the waveform of sounds and spectrogram by using the program SoundEdit, Signalize, Statview 512+for the Macintosh computer. The duration of each segment was measured by searching for the boundaries between the preceding vowels and consonants, and between the consonants and the following vowels. The study led to the conclusion that. 1. With the palatal plate, the duration of all the tested words increased and the duration increased more with the resin plate than with the metal plate. 2. With the palatal plate, the duration of all the preceding vowels, consonants, and following vowels increased, but the temporal structure of the tested words was maintained. 3. As for the manner of articulation, fricative /s/(ㅅ) was greatly influenced by both kinds of palatal plates. 4. As for the place of articulation, alveolar sounds /d/(ㄷ), /n/(ㄴ) were greatly influnced by the kinds of palatal plates, and the velar sounds /n/(ㅇ), /g/(ㄱ) were influenced by the platal plates, but the kind of the palatal plates did not show any significance. 5. As for the lenis/fortis, lenis was influenced more by the kind of the palatal plates. 6. As for the influence of vowels upon each segment in the tested words, palatal vowel /i/(ㅣ) had greater influence than pharyngeal vowel /a/(ㅏ), and following vowels than preceding vowels.

• Journal of Oral Medicine and Pain
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• v.16 no.1
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• pp.103-111
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• 1991

This study was performed to observe the effect of micro-wave diathermy and ultrasonic-wave diathermy on the craniomandibular disorder patients. 19 patients were classified into 12 acute and 7 chronic groups according to the duration of 6 months. They were treated with micro-wave diathermy and ultrasonic-wave diathermy for 2 weeks and pain, maximum comfortable opening, active range of motion were checked before and after therapy. Electromyographic activities of temporal and masseter muscles were also measured at physiologic rest position, clenching and mastication before and after therapy. The obtained results were as follows : 1. After treatment, pain were reduced and active range of motion and maximum comfortable opening were increased. 2. Temporoal and masseter muscle activities of post-treatment in rest position, clenching and mastication were lower than those of pre-treatment. 3. In rest position, temporal and masseter muscle activities of pre-treatment on affected sides were higher than those on unaffected sides, but there were no differences in muscle activities between affected ad unaffected sides on clenching and mastication in pre and post-treatment respectively. 4. There were no significant differences in active range of motion, pain and maximum comfortable opening between acute and chronic groups in pre and post-treatment but there were significant differences between pre-treatment and post-treatment in acute and chronic groups respectively. 5. Muscle activities of masseter and temporal muscles in acute and chronic patients were reduced in rest position after treatment.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.1
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• pp.37-45
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• 2015

Recent droughts in South Korea have had large economic and environmental impacts across the country. Changes in rainfall and hydrologic patterns due to climate change can potentially increase the occurrence of extreme droughts and affect the future availability of water resources. Therefore, it is necessary to evaluate drought vulnerability for water resources planning and management, and identify the appropriate mitigation actions to conduct a drought risk analysis in the context of climate change. The objective of this study is changes in the temporal trends of drought characteristics in South Korea to examine drought impacts under climate change. First, the changes of drought occurrence were analyzed by applying the Standardized Precipitation Evapotranspiration Index (SPEI) for meteorological data on 54 meteorological stations, and were analyzed for the past 30 years (1981-2010), and Representative Concentration Pathways (RCP) climate change scenarios (2011-2100). Second, the changes on the temporal trends of drought characteristics were performed using run theory, which was used to compare drought duration, severity, and magnitude to allow for quantitative evaluations under past and future climate conditions. These results show the high influence of climate change on drought phenomenon, and will contribute to water resources management and drought countermeasures to climate change.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6B
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• pp.513-526
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• 2009

The flood control countermeasure establish for reducing of the flood damages. Design frequency usually reflects the current situation of the station, the importance and the design rainfall. Therefore, this study calculated frequency for duration maximum rainfall with the area which happened the flood damages by main heavy rainfall events recently. Also, to analyze for the temporal characteristics of rainfall event exceed by design rainfall, excess rainfall and excess frequency and excess rainfall per event calculated. To grasp the temporal variation, About excess rainfall and excess frequency and excess rainfall per event have analyzed by change and trend test. Also, rainfall observatory did grouping by cluster analysis using position of rainfall observatory and characteristic timely rainfall. For the grouping rainfall observatory by the cluster analysis calculated average of excess rainfall and excess frequency and excess rainfall per event. To compare for the temporal characteristics, the change and trend test had analyzed about excess rainfall, excess frequency by regional groups.

• Speech Sciences
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• v.14 no.1
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• pp.137-147
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• 2007

The purpose of this study was to examine the syllable structures of ten Korean numeric sounds produced by ten students. Each sound was normalized by its maximum intensity value and divided into onset, vowel, and coda sections after finding abrupt or visible changes in energy values or cumulative values of lower spectral energy at each pulse point using four Praat scripts. Then, segmental durations and cumulative intensity values of each syllable were obtained to find a statistical summary of the syllable structure. Intensity values at 100 proportional time points were also collected to compare the ten sounds. Results showed as follows: Firstly, there was not much deviation from the grand average duration and intensity for the majority of the sounds except the two diphthongal sounds on which their boundary points varied among the speakers. Secondly, the onset point for the CV or CVC category sounds and the boundary between the vowel and the nasal or lateral sound were easy to identify, which may be automatically traced later. Thirdly, there seems some tradeoff among the sections maintaining the same total duration per each syllable. Further studies on syllables with various onsets or codas would be desirable to make a general statement on the Korean syllable structure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1427-1435
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• 2002

The main aim of the present article is numerically to investigate the micro-scale heat transfer phenomena in a silicon microstructure irradiated by picosecond-to-femtosecond ultra-short laser pulses. Carrier-lattice non-equilibrium phenomena are simulated with a self-consistent numerical model based on Boltzmann transport theory to obtain the spatial and temporal evolutions of the lattice temperature, the carrier number density and its temperature. Especially, an equilibration time, after which carrier and lattice are in equilibrium, is newly introduced to quantify the time duration of non-equilibrium state. Significant increase in carrier temperature is observed for a few picosecond pulse laser, while the lattice temperature rise is relatively small with decreasing laser pulse width. It is also found that the laser fluence significantly affects the N 3 decaying rate of Auger recombination, the carrier temperature exhibits two peaks as a function of time due to Auger heating as well as direct laser heating of the carriers, and finally both laser fluence and pulse width play an important role in controlling the duration time of non-equilibrium between carrier and lattice.

• Speech Sciences
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• v.15 no.4
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• pp.19-27
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• 2008

Several studies on the pronunciation of English vowels point out that Korean learners have difficulty distinguishing English tense and lax vowel pairs. The acoustic comparisons of those studies are mostly based on the formant measurement at one time point of a given vowel section. However, the English lax vowels usually show dynamic changes across their syllable peaks and subjects' English levels account for various conflicting results. The purposes of this paper are to compare the temporal duration and dynamic formant tracks of English tense and lax vowel pairs produced by five Korean and five American males. The subjects were graduate students of an American state university. Results showed that both the Korean and American males produced the vowels with comparable durations. The duration of the front tense-lax vowel pair was longer than that of the back vowel pair. From the formant track comparisons, the American males produced the tense and lax pairs much more distinctly than the Korean male speakers. The results suggest that the Korean males should pay attention to the F1 and F2 movements, i.e., the jaw and tongue movements, in order to match those of the American males. Further studies are recommended on the auditorily acceptable ranges of F2 variation for the lax vowels.

• Clinical and Experimental Pediatrics
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• v.63 no.5
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• pp.171-177
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• 2020

Low-grade epilepsy-associated neuroepithelial tumors (LEATs) are responsible for drug-resistant chronic focal epilepsy, and are the second-most common reason for epilepsy surgery in children. LEATs are extremely responsive to surgical treatment, and therefore epilepsy surgery should be considered as a treatment option for LEATs. However, the optimal time for surgery remains controversial, and surgeries are often delayed. In this review, we reviewed published article on the factors associated with seizure and cognitive outcomes after epilepsy surgery for LEATs in children to help clinicians in their decision whether to pursue epilepsy surgery for LEATs. The achievement of gross total resection may be the most important prognostic factor for seizure freedom. A shorter duration of epilepsy, a younger age at surgery, and extended resection of temporal lobe tumors have also been suggested as favorable prognostic factors in terms of seizure control. Poor cognitive function in children with LEATs is associated with a longer duration of epilepsy and a younger age at seizure onset.