• The korean journal of orthodontics
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• v.45 no.5
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• pp.226-235
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• 2015

Objective: The purpose of this retrospective study was to investigate short-term and long-term skeletodental outcomes of Class III activator treatment. Methods: A Class III activator treatment group (AG) comprised of 22 patients (9 boys, 13 girls) was compared with a Class III control group (CG) comprised of 17 patients (6 boys, 11 girls). The total treatment period was divided into three stages; the initial stage (T1), the post-activator treatment or post-mandibular growth peak stage (T2), and the long-term follow-up stage (T3). Cephalometric changes were evaluated statistically via the Mann-Whitney U-test and the Friedman test. Results: The AG exhibited significant increases in the SNA angle, ANB angle, Wits appraisal, A point-N perpendicular, Convexity of A point, and proclination of the maxillary incisors, from T1 to T2. In the long-term follow-up (T1-T3), the AG exhibited significantly greater increases in the ANB angle, Wits appraisal, and Convexity of A point than the CG. Conclusions: Favorable skeletal outcomes induced during the Class III activator treatment period were generally maintained until the long-term follow-up period of the post-mandibular growth peak stage.

• Journal of the Korean Solar Energy Society
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• v.33 no.5
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• pp.1-8
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• 2013

Wind resource data of short-term period has to be corrected a long-term period by using MCP method that Is a statistical method to predict the long-term wind resource at target site data with a reference site data. Because the field measurement for wind assessment is limited to a short period by various constraints. In this study, 2 different MCP methods such as Linear regression and Matrix method were chosen to compare the predictive accuracy between the methods. Finally long-term wind speed, wind power density and capacity factor at the target site for 20 years were estimated for the variability of wind and wind energy. As a result, for 20 years annual average wind speed, Yellow sea off shore wind farm was estimated to have 4.29% for coefficient of variation, CV, and -9.57%~9.53% for range of variation, RV. It was predicted that the annual wind speed at Yellow sea offshore wind farm varied within ${\pm}10%$.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.2
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• pp.51-60
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• 1991

The main objective of this study is to examine the adaptability for the large watershed of the storage tank model which can be applied for the analysis of both long and short terms runoff developed on the basis of hydrologic data for a smaH mountaineous watershed. The results obtained in this study are summarized as follows ; 1. Areal rainfalls of the Dae Chong watershed were calculated by Thiessen method composed of 9 Thiessen networks. 2. Optimal parameters for two types, Model A and Model B of tank models were derived through calibration procedure by standardized Powell method. 3. Monthly simulated flows of Model B are seemed to be closer to the monthly observed than those of Model A during calibration period in the long terms runoff. 4. Relative errors for the simulated flood flows of Model B were apperaed as lower percentage to the observed than those of Model A during calibration period in the short terms runoff. 5. Daily simulated hydrographs of Model B are seemed to be closer to the daily observed than those of Model A during verification period in the long terms runoff. Significance of Model B was highly acknowledged in comparison with Model A in the correlation analysis between annual observed and annual simulated runoff. 6. Reproducibility of simulated flows for Model B is generally seemed to be better than that of Model A during calibration period in the short terms runoff. 7. It can be concluded that reproducibility of Model B is superior to that of Model A in the long and short terms runoff even a large watershed like the result of the small one. 8. It was verified that adaptability for the large watershed of Model B is superior to that of Model A between the two models which were developed by a small watershed characteristics for both long and short terms runoff. 9. Further study for getting a suitable tank model is desirable to be established by the decision, calibration method of initial parameters of tank model and by additional application of another watershed with different watersheds and meterological characteristics.

• Journal of Environmental Science International
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• v.10 no.1
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• pp.27-33
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• 2001

In order to study the long-term change of heavy metal concentrations in the Kumho river water, water analysis was conducted at 13sites surrounding the Kumho river system for 18times from September 1993 to August 1999. Analytical items for the study of water quality are Cu, Zn, Cd, Cr, Fe, Mn and Pb. The six year term studied in this work was divided into Part I and Part II, which covers the period from September 1993 to August 1996 and the period from September 1996 to August 1999, respectively. The mean concentrations of Cu, Zn, Cd, Cr, Fe, Mn and Pb in the unit of ppm for the Part I period showed 0.032, 0.025, 0.006, 0.050, 0.053 and 0.019, respectively. The mean concentrations of Cu, Zn, Cd, Cr, Fe, Mn and Pb in the unit of ppm for the Part II period showed 0.001, 0.001, 0.001, 0.004, 0.020, 0.002 and 0.002, respectively. The heavy metal concentrations in the Kumho river water for te second period were found to be decreased by 1/32, 1/25, 1/6, 1/1.5, 1/2.5, 1/26.5 and 1/9.5 for Cu, Zn, Cd, Cr, Fe, Mn and Pb, respectively. The present results clearly indicate that the water quality in the Kumho river is improving in terms of heavy metal contaminations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.8
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• pp.1791-1796
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• 2011

An optical fiber short period grating of 0.7 nm as a 3 dB wavelength linewidth was fabricated using a Gaussian distributed KrF Eximer laser and a phase mask. This grating has temperature dependancy of 0.01 nm/$^{\circ}C$ over the range of -10 $^{\circ}C$ ~ 70 $^{\circ}C$and no difference between temperature directions. An optical fiber long period grating of 14.22 nm as a 3 dB linewidth was also fabricated using a amplitude mask and has dependancy of 0.01 nm/$^{\circ}C$ over the same range.

• Nuclear Engineering and Technology
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• v.49 no.4
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• pp.825-837
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• 2017

Due to the severe impacts of recent earthquakes, the use of seismic isolation is paramount for the safety of nuclear structures. The diversity observed in seismic events demands ongoing research to analyze the devastating attributes involved, and hence to enhance the sustainability of base-isolated nuclear power plants. This study reports the seismic performance of a seismically-isolated nuclear reactor containment building (NRCB) under strong short-period ground motions (SPGMs) and long-period ground motions (LPGMs). The United States Nuclear Regulatory Commission-based design response spectrum for the seismic design of nuclear power plants is stipulated as the reference spectrum for ground motion selection. Within the period range(s) of interest, the spectral matching of selected records with the target spectrum is ensured using the spectral-compatibility approach. NRC-compliant SPGMs and LPGMs from the mega-thrust Tohoku earthquake are used to obtain the structural response of the base-isolated NRCB. To account for the lack of earthquakes in low-to-moderate seismicity zones and the gap in the artificial synthesis of long-period records, wavelet-decomposition based autoregressive moving average modeling for artificial generation of real ground motions is performed. Based on analysis results from real and simulated SPGMs versus LPGMs, the performance of NRCBs is discussed with suggestions for future research and seismic provisions.

• The Korean Journal of Food And Nutrition
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• v.32 no.5
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• pp.530-535
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• 2019

In this study, the quality characteristics of 30 kinds of long-term matured soy sauce collected from all over Korea classified according to ripening period were analyzed. The longer the soy sauce had to matured, the closer the pH was to neutrality. Acidity decreased as the ripening period increased. Total nitrogen and amino nitrogen content increased as the soy sauce matured. Moisture content decreased with the increasing soy sauce ripening period, and the content of pure extracts increased in proportion to the ripening period. The numbers of bacteria, fungi, and yeast increased in proportion to the maturation period. The content of P was highest in all soy sauce analyzed, followed by K, Ca, Mg, Fe and Zn. Mg and Ca contents decreased with maturing, whereas K increased with maturing.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1231-1238
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• 2022

In this study, the reinforcement effect of the compression-only bridge seismic reinforcement method, which is mainly applied to old bridges, was studied through SSI analysis. As the analysis conditions, acceleration magnitudes of 0.1g, 0.15g, and 0.2 g were applied, and long-period and short-period seismic waves were applied. As a result of the analysis according to the assumed ground characteristics and structure size, the horizontal displacement at the reinforced section was reduced by about 9%, and the long-period seismic wave had a 95% larger displacement than the short-period seismic wave. In addition, an increase in acceleration of 0.1g resulted in a displacement of about 50%, and a large increase in displacement was observed in long-period seismic waves. As a result of the analysis, in the case of the compression-only bridge seismic reinforcement method, there was a reinforcing effect, so the field applicability was excellent.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.51-64
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• 2002

To investigate long-period wave responses in Sokcho Harbor and Cheongcho lagoon, field measurements were made for long-and short-period waves and current velocities using a Directional Waverider, a ultrasonic-type wave gauge, four pressure-type wave gauges, and a current meter. From the data analysis, it was found that the Helmholtz resonant periods of Sokcho Harbor and Cheongcho lagoon are about 13.6 and 54.5 minutes, respectively, and the dominant period of wave induced current in the passage between Sokcho Harbor and Cheongcho lagoon is about 55.2 minutes which depends on Helmholtz resonant condition of the Cheongcho lagoon. It was also found that the energy level of the far-infra-gravity waves during storm conditions is very high compared with that during calm sea conditions. To investigate relationships between far-infra-gravity waves and short-period waves at offshore station, regression analyses were carried out especially for 1) heights, 2) periods, 3) direction and height, 4) height and period between short-and far-infra-gravity waves, respectively. The results showed that the long-period wave height is highly correlated with the short-period wave height. However, no special trend was found for the other relations. In the future far-infra-gravity wave heights on return period around Sokcho Harbor region can be suggested by using extreme value analyses of long term measured data.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.381-388
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• 1999

The existing methods for installation of long steel pipe pile have some uneconomical problems such as increase of installation cost and period due to the welding of two piles and removal of soil plug, and decrease of driving efficiency due to the increase of driving resistance by time effect during the welding of piles and removal of soil plug, etc. Thus, in this study, new installation method for long steel pipe pile is suggested to work out the existing problems, and calibration chamber tests are peformed to investigate both driving and economical efficiency for the suggested method. The test results showed that the new installation method has increase bearing capacity as well as reduce installation cost and period for long steel pipe piles as compared with existing methods.