• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.11a
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• pp.111-114
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• 1999

Off-vertical axis rotator was developed to differentiate each function of the canal and otolith in the vestibular system and evaluate subjective symptoms during postural change. Eye movement induced by various types of rotation was measured in normal subjects. Nystagmus with fast component corresponding to direction of rotation was occurred by sinusoidal earth vertical axis rotation, and the gain of eye movement in vestibuloocular reflex (VOR) was lower than in visual vestibuloocular reflex (VVOR) and higher than in visual fixed vestibuloocular reflex (VFX). Degree of dizziness was proportioned to degree of gain. off-vertical axis rotation was produced severe dizziness than earth vertical axis rotation. These results suggest stimulation of the otolith should be minimized to make a stable and pleasant condition in work and travel.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.41-53
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• 2022

In the excavation work like blasting/excavator work bordering on the urban railway, the dynamic safety of railway structures like tunnel, open-cut box structure and elevated bridge was investigated by numerical analysis in this study. The practically presented criteria on influential zones at the blasting work in the construction industry was numerically checked in cases of the precise vibration-controlled blasting (type II) and the small scale vibration-controlled blasting (type III) and it was shown that the criteria on blasting work methods needed to be supplemented through continuous field tests and numerical analyses. The influence of excavation vibration by mechanical excavators was especially investigated in case of earth auger and breaker. The numerical analysis of tunnel shows that the criteria on vibration velocities from the regression analysis of field test values was conservative. The amplification phenomenon of excavating vibration velocity was shown passing through the backfilling soil between the earth auger and the open-cut box structure. It was shown that the added-vibration on the superstructure of elevated bridge was occurred at the bottom of pile like earthquake when the excavator vibration was arriving at the pile toe. The systematic and continuous research on the vibration effect from excavating works was needed for the safety of urban railway structures and nearby facilities.

• Journal of the Korean earth science society
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• v.34 no.3
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• pp.257-273
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• 2013

The purpose of this study was to describe how one woman became a science docent's exper and how she developed expertise in her field of work as a docent in science museum. A life history approach, one of the qualitative research methods was employed in this study. A docent Ms. Park, had her career as a docent for eight years and she was selected through the procedures as follows. The $1^{st}$ phase of selection, the researcher contacted 56 docents who were working using a convenience sampling method. In the $2^{nd}$ phase of selection, 11 of them were then selected on purpose for further study. Finally docent Paek was selected as a case for this study on the basis of her responses to survey questions and interviews as well as her willingness to participate. Research data were collected through mainly interviews, participant observations, and docents' artifacts. We analyzed data to reveal Ms-Park's life history of how she became a docent, how her work was as a docent, and what efforts she made to become an expert as a docent of science museum. Findings are as follows. First, docent Park demonstrated strong educational beliefs that influenced her field work, as the beliefs have continuously been formed throughout her life experiences. Second, she acquired and organized her practical knowledge of exhibit interpretation through real activities and experiences interacting whith visitors and demonstrating exhibits in science museums. Third, docent Park showed her ability to make full use of surroundings and resources available for developing her expertise on exhibit interpretation more effectively. With these findings in mind, we suggest that a well established docent system as well as its operation, and physical support be needed for increased docents' expertise and meaningful education in science museum.

• Economic and Environmental Geology
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• v.48 no.6
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• pp.451-465
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• 2015

The free-air anomalies are computed using a data set from various types of gravity measurements in the Korean Peninsula area. The gravity values extracted from the Earth Gravitational Model 2008 are used in the surrounding region. The upward continuation technique suggested by Dragomir is used in the computation of the external free-air anomalies at various altitudes. The integration radius 10 times the altitude is used in order to keep the accuracy of results and computational resources. The direct geodesic formula developed by Bowring is employed in integration. At the 1-km altitude, the free-air anomalies vary from -41.315 to 189.327 mgal with the standard deviation of 22.612 mgal. At the 3-km altitude, they vary from -36.478 to 156.209 mgal with the standard deviation of 20.641 mgal. At the 1,000-km altitude, they vary from 3.170 to 5.864 mgal with the standard deviation of 0.670 mgal. The predicted free-air anomalies at 3-km altitude are compared to the published free-air anomalies reduced from the airborne gravity measurements at the same altitude. The rms difference is 3.88 mgal. Considering the reported 2.21-mgal airborne gravity cross-over accuracy, this rms difference is not serious. Possible causes in the difference appear to be external free-air anomaly simulation errors in this work and/or the gravity reduction errors of the other. The external gravity field is predicted by adding the external free-air anomaly to the normal gravity computed using the closed form formula for the gravity above and below the surface of the ellipsoid. The predicted external gravity field in this work is expected to reasonably present the real external gravity field. This work seems to be the first structured research on the external free-air anomaly in the Korean Peninsula area, and the external gravity field can be used to improve the accuracy of the inertial navigation system.

• Journal of the Korean earth science society
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• v.34 no.3
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• pp.235-248
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• 2013

The purpose of this study is to investigate a feasibility of a small mountain as a field work site on geological features in Earth sciences classes at all levels. Mt. Geumdang with the height of 305 meters from the sea level is located in the metropolitan city of Gwangju, southern part of Korea. The study reviews the human and natural geography, geological features, geomorphic resources, landscapes, and conveniences of the mountain for a possibility of meaningful field work. The population within the distance of 5 km from the mountain stands at about 620,000 and 170,000 of them are students and teachers. Mt. Geumdang has a warm temperature climate with low rainfall throughout the year, so it seems suitable for a field survey. Road network and public transportation system around the area are well-developed and easily accessible. Mt. Geumdang shows various rock type and geological structures. The basement rock is Gwangju granite, which is plutonic body of the Jurassic period. Also, granophyre (micrographic granite) and various volcanic rocks distributed as bedded tuff, lapilli tuff, and rhyolite of the Cretaceous period. Many andesitic and felsic dykes were intruded into the rock by joint system. In Mt. Geumdang, many geomorphic resources are found such as U shaped mountain, joint, fault, lamination, gnamma, tor, cliff, groove, block stream and block field, regolith, and saprolite. It has a beautiful mountain scenery including the view of whole shape of Mt. Mudeung, panoramic view of the town, Pungam lake, World Cup stadium and sunrise and sunset. Furthermore, the area has ecologic study facilities related to geology, emergency medical and convenience facilities for field works. In conclusion, Mt. Geumdang is highly feasible for geological field studies at all levels.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.248-259
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• 2010

In the case of relatively good ground and construction condition in the deep excavation for the construction of subway, railway, building etc., flexible earth retaining systems are often used in an economical point of view. It is generally known that the mechanism of behavior in the flexible earth retaining system is relatively more complicated than the rigid earth retaining system. Moreover in the case of long span strut supporting system the analysis of strut axial force change becomes more difficult when the differences of ground condition and excavation work progress on both sides of excavation section are added. When deeper excavation than the specification or installation delay of supporting system is done or change of ground condition is faced due to the construction conditions during construction process, lots of axial force can be induced in some struts and that can threaten the safety of construction. This paper introduces one example of long span deep excavation where struts and rock bolts were used as a supporting system with flexible wall structure. The characteristics of ground deformation and strut axial force change, the measured data obtained during construction process, were analysed, the effects of relatively deeper excavation than the specification on one excavation side and rapid drawdown of ground water level on the other excavation side were deeply investigated from the viewpoint of mutual influences between ground deformations of both excavation sides and strut axial force changes. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.4
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• pp.913-919
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• 2014

This study regards to a method how to select the optimized earth retaining technology among four target technologies which are applied to underground construction work by analyzing relative weight values of major influence factors. In this study, major affected zone and influence factors are analyzed through questionnaire survey to select a suitable earth retaining technology for downtown area, and an optimized earth retaining technology is proposed by using the matrix analysis based on them. Also, by systematically analyzing the weight values and methods of alternatives selection through consideration the importance of alternatives evaluation criteria, the importance of affected zones is evaluated to determine the optimized alternative. It is concluded that when performing the analysis to select the earth retaining technology which should consider a variety of constraints, the convergence with information processing technology in the field of IT is effective to analyze and optimize many constraints.

• Journal of Powder Materials
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• v.17 no.2
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• pp.148-153
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• 2010

Thermal barrier systems have been widely investigated over the past decades, in order to enhance reliability and efficiency of gas turbines at higher temperatures. Yttria-stabilized zirconia (YSZ) is one of the most leading materials as the thermal barriers due to its low thermal conductivity, thermodynamic stability, and thermal compatibility with metal substrates. In this work, rare-earth oxides with pyrochlore phases for thermal barrier systems were investigated. Pyrochlore phases were successfully formed via solid-state reactions started from rare-earth oxide powders. For the heat-treated samples, thermo-physical properties were examined. These rare-oxide oxides showed thermal expansion of $9{\sim}12{\times}10^{-6}/K$ and thermal conductivity of 1.2~2.4 W/mK, which is comparable with the thermal properties of YSZ.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.308-319
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• 2009

In the case of relatively good ground and construction condition in the deep excavation for the construction of subway, railway, building etc., flexible earth retaining systems are often used in an economical point of view. It is generally known that the mechanism of behavior in the flexible earth retaining system is relatively more complicated than the rigid earth retaining system. Moreover in the case of long span strut supporting system the analysis of strut axial force change becomes more difficult when the differences of ground condition and excavation work progress on both sides of excavation section are added. When deeper excavation than the specification or installation delay of supporting system is done or change of ground condition is faced due to the construction conditions during construction process, lots of axial force can be induced in some struts and that can threaten the safety of construction. This paper introduces two examples of long span deep excavation where struts and rock bolts were used as a supporting system with flexible wall structure. And the sections of two examples are 50 meters apart in one construction site, they have almost similar design and construction conditions. The characteristics of ground deformation and strut axial force change were analysed, the similarity and difference between measurement results of tow examples were compared and investigated. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• Korean Journal of Remote Sensing
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• v.36 no.4
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• pp.573-586
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• 2020

PM (particulate matter) is of interest to everyone because it can have adverse effects on human health by the infiltration from respiratory to internal organs. To date, many studies have made efforts for the prediction of PM10 and PM2.5 concentrations. Unlike previous studies, we conducted the prediction of tomorrow's PM10 concentration for the Air Korea stations using Chinese PM10 data in addition to the satellite AOD and weather variables. We constructed 230,639 matchups from the raw data over 3 million and built an RF (random forest) model from the matchups to cope with the complexity and nonlinearity. The validation statistics from the blind test showed excellent accuracy with the RMSE (root mean square error) of 9.905 ㎍/㎥ and the CC (correlation coefficient) of 0.918. Moreover, our prediction model showed a stable performance without the dependency on seasons or the degree of PM10 concentration. However, part of coastal areas had a relatively low accuracy, which implies that a dedicated model for coastal areas will be necessary. Additional input variables such as wind direction, precipitation, and air stability should also be incorporated into the prediction model as future work.