• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.450-452
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• 2004

Using factor analysis and bivariate comparisons of major components in ground water, three geochemical processes were identified as controlling factors of ground water chemistry; 1) natural mineralization by water rock interactions, 2) effect of seawater which includes salinization by seawater near seashores and deposition of sea salt, and 3) nitrate contamination by N fertilization. Contribution of rainfall was also estimated from the measured composition of wet deposition. The geochemical processes were separated using total alkalinity as an indicator for natural mineralization, Cl for effect of seawater, and nitrate for N fertilization. Relatively high correlation of major components with nitrate suggests that nitrification of nitrogenous fertilizers significantly affects ground water chemistry. Total cations derived from nitrate sources have good linearity for nitrate in equivalent basis with a slope of 1.8, which is a mean of proton production coefficients in nitrification of two major compounds in nitrogenous fertilizers, ammonium and urea. Contribution of nitrate sources to base cations, Cl, and SO$_4$ in ground water was determined considering maximum contribution of natural mineralization to estimate a threshold of the effect of N fertilization for ground water chemistry, which shows W fertilization has a greatest effect than any other processes in ground water with nitrate concentration greater than 50 mg/L for Ca, Mg, Na and with concentration greater than 30 mg/L for Cl and SO$_4$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.8
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• pp.426-432
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• 2004

This paper presents a systematic approach of measurement, modeling and analysis of grounding system impedance in the field of lightning protection system and intelligent power equipments. The measurement and analysis system of ground impedance is based on a computer aided technique. The magnitude and phase of ground impedance were determined by the novel measurement and analysis using the revised fall-of-potential method. The ground impedances of the ground rod of 50 m long are considerably dependent on the frequency. The ground impedance is mainly resistive in the frequency range of 3-20 kHz. At higher frequencies, the reactive components of the ground impedances are no longer negligible and the inductance of the ground rod was found to be the core factor deciding the ground impedance. Although the steady-state ground resistance of the ground rod of 50 m was less than that of the ground rod of 10 m, the ground impedances of the ground rod of 50 m over the frequency range of more than 60 kHz were much greater than those of the ground rod of 10 m. Furthermore, the equivalent circuit model based on the measured data was proposed. and the calculated results were in approximately agreement with the measured data.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.272-273
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• 2007

This paper presents the characteristic of rectangular and octagonal spiral inductor using PGS(Patterned Ground Shield). We investigated variation of inductance and Q-factor with changing of turn number at fixed width, spacing and inner diameter. We confirmed that characteristic of inductance and Q-factor be appled PGS in rectangular and octagonal types spiral inductor by EM simulation tool. Inductance decreased irrespective of structure but Q-factor increased. When PGS not exist, Q-factor of Inductor is analogous at classification frequency but, rectangular is a few larger then octagonal in small turn number. The other side, When PGS is inserted, we confirmed that octagonal lager then rectangular in many turn number. Q-factor is improved in case of octagonal structure and small turn number by PGS effect.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.1991-1998
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• 2015

This paper presents the antenna factor characteristics of a calculable dipole antenna with a hybrid balun, installed above ground plane vertically and horizontally, using Method of Moments (MoM). An expression for the antenna factor is formulated using the concept of power mismatch loss. The input impedance and effective length of the antenna, which are in the formula of the antenna factor, are calculated using the MoM. The results show that the antenna factors above a ground plane are agreed with the free space antenna factors within ± 0.14 dB. The horizontal antenna factors are varied more by 0.2 dB than the vertical antenna factors.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.591-604
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• 2008

In this study, two design examples of drilled shafts on soft ground in Ho-Chi-Minh City, Vietnam are introduced. One is for a 27-story apartment and the other is for a Arch bridge over Saigon river. Unlikely the normal cases in Korea, all of the bored pile foundations are supposed to be placed on soil layers. Therefore, skin friction between pile and ground is the most crucial design parameter. Three methods using SPT N value of sandy soil -Korean Road Bridge Code(1996), Reese and Wright (1977), and O'Neill and Reese (1988)- were adopted to obtain an ultimate axial bearing capacity. In order to verify the calculated bearing capacity, 3 sets of static load test and a Osterberg Cell test were performed at an apartment site and a bridge site respectively. LRFD (Load Resistance Factored Design) method was compared with ASD (Allowable Stress Design) method. On application of ASD method, safety factor for skin friction was adopted as 2 or 3 while safety factor for end bearing was 3. The design bearing capacities from ASD method matched well with those from LRFD method when safety factor for skin friction was adopted as 2.

• Journal of International Academy of Physical Therapy Research
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• v.10 no.1
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• pp.1706-1710
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• 2019

Background: Despite frequent shoulder injuries of rotator cuff muscle of golfers by the result of overuse and poor swing mechanics, there is little research on shoulder specific rehabilitation exercises for injured rotator cuff muscle and golf swing Objective: To examined the effect of rehabilitation exercise for golfers on the X factor and ground reaction force (GRF) according to phase of the golf swing. Design: Crossover study Methods: The participants were 13 amateur golfers selected for a 4 week rehabilitation exercise for golfers. A rehabilitation exercise for golfers consisting of 5 steps and 4 items (sleeper stretch, full side plank, push up to plank, high plank knee unders) were applied to all participants. A three dimensional motion analyzer and force platform (SMART-E, BTS, Italy) were used to measure the X factor (angle between shoulder and pelvis at top of back swing) and GRF according to phase of the golf swing. All dependent variables were measured before and after exercise. The collected data was analyzed using the paired t test and SPSS 21.0. Results: The GRF had a statistically significant increase in the impact phase and ratio impact/weight after rehabilitation exercise for golfers (p<.05). The X-factor, GRF in top of back swing and finish were no significant differences between before and after exercise (p>.05). Conclusions: These results suggested that rehabilitation exercise for golfers was effective for increasing GRF in the impact phase and ratio impact/weight for amateur golfer.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.89-100
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• 2008

Applying graph and correlation developed in other countries to the domestic field has limits. Therefore, it is necessary that Piezocone factor should be determined by including ground characteristics obtained from various test results in the domestic site for better application. In this study, laboratory tests and field tests were performed to find the characteristics of soft ground which was widely distributed around Siwha lake. A comparative analysis of these tests with Piezocone penetration test was performed and the Piezocone factor was estimated by correlationship analysis of undrained shear strength and cone resistance. Also, an appropriate Piezocone factor in the study site was reestimated by utilizing statistical analysis method for deriving reliable result.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1876-1878
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• 2004

A systematic approach of measurement, modeling and analysis of grounding system impedance is presented. The measurement and analysis system of ground impedance is based on a computer aided technique. The ground impedances of the ground rod are considerably dependent on the frequency. The ground impedance is mainly resistive in the frequency range of 3-20 kHz. At higher frequencies, the reactive components of the ground impedances are no longer negligible and the inductance of the ground rod was found to be the core factor deciding the ground impedance. As a consequence, the equivalent circuit model based on the measured data was proposed, and the calculated results were in approximately agreement with the measured data.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.211-214
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• 2004

The measurement system of ground impedance is based on a computer aided technique. The magnitude and phase of ground impedance were determined by the novel measurement and analysis using the revised fall-of-potential method. The ground impedances of the ground rod of 30 m long are considerably dependent on the frequency. The ground impedance is mainly resistive in the frequency range of 3-20 kHz. At higher frequencies, the reactive components of the ground impedances are no longer negligible and the inductance of the ground rod was found to be the core factor deciding the ground impedance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.116-117
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• 2017

The most important factor when designing coastal and offshore concrete structures is durability. However, concrete in marine environment is exposed to physical and chemical deterioration of seawater, which might easily lead to low quality. The purpose of the present study is to understand advantages of adding ground solidificaton materials by comparatively analyze the seawater resistance of general concrete and environmental-friendly ground solidification materials.