• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.604-613
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• 2016

The sea level of the Earth is rising approximately 2.0mm per year (global average value) due to thermal expansion of sea water, melting of glaciers and other causes by global warming. However, when it comes to design a river, the standard of design water level is decided by analyzing four largeness tide value and harmonic constant with observed tidal water level. Therefore, it seems the external water level needs to consider an increasing speed of the seawater level which corresponds to a design frequency. In the present study, the hourly observed tidal water level targeting 47 tidal stations operated by Korea Hydrographic and Oceanographic Administration (KHOA) from beginning of observation to 2015 per hour has been collected. The variation of monthly and yearly and increasing ratio have been performed divided 4 seas such as the Southern, East, Western, and Jeju Sea. Also, the external water level existing design for rivers nearby a coast was been reviewed. The current study could be used to figure out the cause of local seawater rise and reflect the external water level as basic data.

• 한국해양학회지
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• v.15 no.2
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• pp.123-128
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• 1980

Variabilities of tidal range at Inchon were described based on observed values. Relationships between tidal ranges and harmonic costants of tide were also examined. Fortnightly variation is predominant and its range is 571.3cm. Mean of maximum spring range(ΔH/sun max/) is 887.2cm and that of minimum neap range(ΔH/sun min/) is 315.9cm. Mean tidal range(ΔH) is 634.3cm. Diurnal inequality is shown about 141cm on an average and monthly inequality is also shown about 100cm. Yearly inquality appears with a range of about 35cm, maxima in March and September, and minima in June and December. There may exist 18 1 years periodicity with a range of about 45cm. There are some relationships between ridal ranges and amplitudes of M$\_$2/ and S$\_$2/, such as ΔH=2.172 H$\_$m/, ΔH$\_$max/=3.043 H$\_$m/, ΔH$\_$min/=1.071 H$\_$m/, ΔH$\_$max/=2.198 (H$\_$m/ + H$\_$s/), and ΔH$\_$min/=1.740 (H$\_$m/ - H$\_$s/).

• KDI Journal of Economic Policy
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• v.35 no.2
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• pp.107-131
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• 2013

In this paper, we test and estimate the stochastic non-fundamental trend in Korean stock market. For this, following Kim (2011), we exploit that the long-run equilibrium stock price may be decomposed into fundamental and stochastic non-fundamental trends (i.e., the sum of dividend innovations and a part that are orthogonal with the dividend innovations) by using the Beveridge-Nelson decomposition and projections. In this VAR construction, there is an error correction mechanism through which stock prices converge to their long-run equilibrium, which also contain the stated stochastic non-fundamental trend as well as fundamental trend. The estimation and test results using yearly data from the Korea (1976-2012) indicated that fluctuations in stock prices during that period can be explained mainly not by the stochastic non-fundamental trend but by the dividend trend. However, during some periods like after Seoul Olympic Games, we may observe the non-fundamental trend affected to the stock price variation.

• Journal of the Korean Solar Energy Society
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• v.35 no.4
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• pp.25-34
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• 2015

This research is carried out to provide fundamental data for the design of solar photovoltaic systems. Methodologically, the solar radiation installations from 10 different pyreheliometers are measured, which are set up at 6 and 4 different levels of tilts and azimuth, respectively. Maximum of a yearly accumulated solar radiation is $1,569.8kWh/m^2{\cdot}year$ with a tilt angle of $30^{\circ}$ and an azimuth angle of $0^{\circ}$(south), $1,558.5kWh/m^2{\cdot}year$ with an azimuth angle of $0^{\circ}$(south) in combination of a tilt angle of $35^{\circ}$. This paper estimates that in designing fixed solar photovoltaic systems with a tilt angle of $12.5^{\circ}{\sim}50^{\circ}$(south) and a tilt angle of $35^{\circ}$ in combination of an azimuth angle of $S45^{\circ}W{\sim}S45^{\circ}E$, a tilt angle and an azimuth angle will cause a maximum 6.8% and 9.9% of efficiency variation respectively, depending on a installed solar module's angle and direction.

• Magazine of the Korean Society of Agricultural Engineers
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• v.29 no.2
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• pp.53-63
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• 1987

Due to their wide range of application, deterministic comprehensive hydrologic models using digital computers have been developed in all countries of the world and researches are being undertaken for their appropriate applications. The aim of this study has been to demonstrate the practical implementation of a physically based distributed hydrologic model, the USDAHL-74 model and to investigate its ability to simulate the long term estimate of water balance quantities in a Korean mountainous watershed. Application of the model to Dochuk watershed indicates the following results. 1.Since the USDAHL-74 model includes all the major components of the hydrologic cycle in agricultural watersheds, thus is comprehnsive, the model seems to have a wide range of application from the fact that simulation results obtained are not only runoff volumes m various time units but their spatial variation as well as even soil moisture within the watershed. 2.An approximate calibration to determine the parameter values in the model using various data obtained from D0chuk shed shows that the simulation error of yearly runoff volume is only 0.6 % and a correlation coefficient between observed daily runoff volume and simulated one is 0.91 in all calibrated period.3.As a verification test of the model, runoff volumes are simulated using 1986 year data without changing the parameter values determined by 1985 year data. The tests show that the USDAHL-74 model is a flexible tool and that realistic production to simulate the long term estimate of runoff in Korean mountainous watershed could be obtained using only a short period of calibration.4. Despite of the encouraging results, there still remain minor problems concerning the practical application of the model to improve the result of simulations. Some of these are the small descrepancies between observed and simulated daily runoff volume appeared in the vicinity of peaks and the recession of1 the daily hydrographs and the model performance for the frozen ground and melting process in the model. 5. Alough the use of parameter with physical significance and the ability to improve calibrations on the basis of physical reasoning represents advantages in the simulation for ungaged watersheds, further researches are needed to use the USDAHL-74 mode to simulate runoff in ungaged watersheds.

• Journal of Hydrogen and New Energy
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• v.27 no.2
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• pp.182-191
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• 2016

In the present work, a solar assisted heat pump (SAHP) system with a hybrid collector was analyzed. For this, a simplified thermodynamic model was developed. Based on the proposed model, the heat transfer rate, COP, and the annual operating hour of the SAHP system were estimated. The effect of the variation of system design parameters on the performance of the system was also examined. From the results, the performance was improved with increasing the effectiveness of heat exchangers and decreasing the difference between the evaporation temperature and the outlet brine temperature of the hybrid collector loop. Finally, the performance of SAHP system with a hybrid collector was compared with that of conventional serial and parallel SAHP systems. The SAHP system with a hybrid collector was substantially better than a series system and slightly worse than a parallel system for both the yearly averaged heat transfer rate and COP. However, the annual operating hour of the SAHP system with a hybrid collector was much better than that of a parallel system.

• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.287-293
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• 2016

The equatorial region of the Earth's ionosphere exhibits large temporal variations in electron density that have significant implications on satellite signal transmissions. In this paper, the first observation results of the variations in the trough of the equatorial ionospheric anomaly at the permanent Global Navigation Satellite System (GNSS) site in Chuuk (Geographic: $7.5^{\circ}N$, $151.9^{\circ}E$; Geomagnetic: $0.4^{\circ}N$) are presented. It was found that the daytime Global Positioning System (GPS) total electron content (TEC) values vary according to the 27 day period of solar rotation, and that these trends show sharp contrast with those of summer. The amplitudes of the semi-annual anomaly were 12.4 TECU (33 %) on $19^{th}$ of March and 8.8 TECU (23 %) on $25^{th}$ of October respectively, with a yearly averaged value of 38.0 TECU. The equinoctial asymmetry at the March equinox was higher than that at the October equinox rather than the November equinox. Daily mean TEC values were higher in December than in June, which could be interpreted as annual or winter anomalies. The nighttime GPS TEC enhancements during 20:00-24:00 LT also exhibited the semi-annual variation. The pre-midnight TEC enhancement could be explained with the slow loss process of electron density that is largely produced during the daytime of equinox. However, the significant peaks around 22:00-23:00 LT at the spring equinox require other mechanisms other than the slow loss process of the electron density.

• The Journal of the Korean Society for Microbiology
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• v.22 no.3
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• pp.295-300
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• 1987

Salmonella strains isolated from blood in the Dong-san hospital, Taegu during the period from 1971 to 1986 were studied for species distribution, drug resistance, and R plasmids. The number of strains was 2,527 and all of them were classified into S. typhi and S. paratyphi A. Approximately 300 strains were isolated in the period from 1974 to 1976 and 1978, 268 in 1982, and 204 in 1983, but the numbers isolated in the 1980's have a tendency to decrease as compared with those of the 1970's. S. typhi occupied 85% or more of strains isolated until 1976, but the isolation frequency decreased yearly with some variation, and S. paratyphi A increased gradually from 1974. Only 4 strains of S. paratyphi A were resistant to some drugs, and the resistance was not transferred to E. coli by conjugation. S. typhi resistant to drugs were 15 in 1971 through 1973, 24 in 1974, and 13 in 1975, but afterwards only few resistant strains were isolated. These strains were resistant to two or more drugs; chloramphenicol(Cm), tetracycline(Tc), streptomycin(Sm), sulfisomidine(Su), ampicillin(Ap), and kanamycin(Km) and no strain resistant to other drugs tested was found. Strains resistant to 3 or less drugs didn't transfer the resistance to E. coli by conjugation. There were 15 strains resistant to four or more drugs, and were isolated in years from 1972 to 1976. These strains transferred the resistance to E. coli, and the resistance was considered to be mediated by R plasmids. Transfer frequency was higher at $25^{\circ}C$ than at $37^{\circ}C$ and patterns of transferred resistance were Cm, Tc, Sm, Su; Ap, Km; Cm. R plasmids having markers of Cm, Tc, Sm and Su were classified into Inc H1.

• Wind and Structures
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• v.23 no.3
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• pp.211-229
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• 2016

In recent years, the frequency and duration of supply interruption in electric power transmission system due to flashover increase yearly in China. Flashover is usually associated with inadequate electric clearance and often takes place in extreme weathers, such as downbursts, typhoons and hurricanes. The present study focuses on the wind-induced oscillation of conductor during the process when a downburst is passing by or across a specified transmission line. Based on a revised analytical model recently developed for stationary downburst, transient three-dimensional wind fields of moving downbursts are successfully simulated. In the simulations, the downbursts travel along various motion paths according to the certain initial locations and directions of motion assumed in advance. Then, an eight-span section, extracted from a practical 500 kV ultra-high-voltage transmission line, is chosen. After performing a non-linear transient analysis, the transient displacements of the conductors could be obtained. Also, an extensive study on suspension insulator strings' rotation angles is conducted, and the electric clearances at different strings could be compared directly. The results show that both the variation trends of the transient responses and the corresponding peak values vary seriously with the motion paths of downburst. Accordingly, the location of the specified string, which is in the most disadvantageous situation along the studied line section, is picked out. And a representative motion path is concluded for reference in the calculation of each string's oscillation for the precaution of wind-induced flashover under downburst.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.2
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• pp.157-160
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• 1988

This studies were conducted to obtain the basic information for the influencial plant age and cultural altitude in change of hop cone yield in Hoeongseong, Korea. The fresh cone yields per 10a were increased by the increase of plant age showing 181.0 kg in 1-year-old, 516.0 kg in 2-year-old, 670.0 kg in 3-year-old, 726.4 kg in 4-year-old and 761.0 kg in 5-year-old. The productivity of fresh cone at each plant age was significantly different from 1 age to 3 age but the productivity over 4-year-old hop plant was not significantly different. In the average hop cone yields, yearly variation was significant, but the yields among the altitudes studied were not significantly different.