• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.170-172
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• 2005

Internal battery ohmic measurements have been a hot topic amongst battery users and battery manufacturers. As a battery deteriorates and loses its capacity, the internal resistance of the battery increases. Everyone seems to agree that measuring the internal parameters of a cell can be very useful in determining a battery's state of health. In this paper experiences show that if a cell's resistance increases by more than25% above its baseline value(known good resistance of new 100% capacity cell), the cell will no loger be able to deliver 80% or more of the rated capacity.

• Geomechanics and Engineering
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• v.29 no.4
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• pp.407-420
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• 2022

Embedded piles, which are typically used in Korea, are precast piles inserted into prebored ground with cement paste. Dynamic pile tests tend to underestimate the bearing capacity of embedded piles because of the undeveloped shaft resistance prior to the curing of the cement paste and the insufficient energy transferred after the curing. In this study, a resistance combination method using the base resistance before the cement paste is cured and the shaft resistance after the cement paste is cured is proposed to obtain a combined load-settlement curve from dynamic pile tests. Two pairs of embedded piles with diameters of 600 and 500 mm are installed. Each pair comprises one pile for the dynamic pile test and another pile for the static load test. The shape of the load-settlement curve obtained using the proposed method is similar to that obtained from the static load test. Thus, the resistances evaluated using the proposed method at selected settlements are similar to those obtained from the static load test. This study shows that the resistance combination method may be used effectively in dynamic pile tests to accurately evaluate the bearing capacity of embedded piles.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1287-1294
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• 2006

A pile is compressed with settlements when loading and bearing capacity is altered along relative displacement of pile/soil on settlement and compression. Settlements of pile displaying limit skin friction is different from displaying tip resistance. Therefore, it is an error in traditional method that bearing capacity of pile is estimated from the sum of limit skin fraction and tip resistance. Accordingly, development of design method considering behavior of load-settlement is needed. In this study, we would like to establish the base for development of design method considering bearing capacity altering along displacement on settlement and compression. For this, we established system and substance of design method. And in order to establish relationship of load-settlement of pile on the type of soil, we analyzed and arranged existing database and pile loading test. On design method, settlement is assumed gradually on each capacity level being assumed gradually. Bearing capacity developing on the pile is obtained on each settlement level. Until the obtained bearing capacity will be equal to assumed capacity, this process is continued with increasing settlement. Load-settlement curve for soil classification is sketched in the process computing settlement on assumed capacity. This design method will be materialized by computation program.

• Journal of the Korean Geotechnical Society
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• v.25 no.2
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• pp.37-44
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• 2009

In this study, estimation methodology for the pile of ultimation lateral resistance, pu, and ultimate lateral capacity, Pu, is based on the CPT cone resistance $q_c$. Preexistent methodologies for ultimate lateral resistance and ultimate lateral capacity have been generally represented with relative density, vertical effective stresses, and various $K_0$ values which are important for analyzing sandy soil. These methodologies, however, did not consider the horizontal effective stress and the effects of construction site conditions. Therefore, CPT-based methodology for the estimation of the ultimate lateral pile load capacity Hu was proposed. Calibration chamber test results were analyzed and compared with calculated results. The proposed estimation methodology for the pile of $p_u$ can be effectively utilized as alternative to preexistent methods.

• Land and Housing Review
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• v.8 no.4
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• pp.233-247
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• 2017

In Europe and the USA, the use of limit state design method has been established, and the Korea Ministry of Land, Transport and Maritime Affairs has implemented the bridge substructure design standard based on the critical state. But Korean piling methods and ground conditions are different from Europe and USA, the limit state design method can not be used immediately. In this study, the resistance coefficient was proposed by comparing and analyzing the results of the static load test(9 times) and dynamic load tests(9 times of EOID and 9 times of Restrike) with the bearing capacity calculated by Meyerhof(LH design standard, Road bridge design standard) method and surcharge load method(using Terzaghi's bearing capacity coefficient and Hansen & Vesic's bearing capacity coefficient). The previous LHI study showed the resistance coefficient of the LH design standard was 0.36 ~ 0.44, and this research result showed the resistance coefficient was 0.39 ~ 0.48 which is about 8% higher than the previous study. In this study, we tried to obtain the resistance coefficient mainly from the static load test and the resistance coefficient was 0.57 ~ 0.69(Meyhof method : LH design standard) based on the ultimate bearing capacity and the resistance coefficient was 0.49 ~ 0.60(Meyhof method : LH design standard) based on the Davissons bearing capacity. The difference of the resistance coefficient between the static and dynamic load test was greater than that we expected, we proposed the resistance coefficient(0.52 ~ 0.62 : Meyerhof method: LH design standard) using the modified bearing capacity of the dynamic load test. Summarizing the result, the coefficient of resistance obtained from the static and dynamic load tests was 0.35 ~ 0.76, which is greater than 0.3 suggested by the Road bridge design standard, so the economical design might be possible using the coefficient of resistance proposed by this study.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.3
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• pp.11-18
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• 2019

The purpose of this study was to estimate the resistance capacity of a traditional wooden house with shear walls made of wood panel. In order to achieve the purpose of the study, the load - displacement test was carried out and the resistance moment values of the shear walls were proposed. The shear walls were made by placing studs with a nominal dimension of $38mm{\times}89mm$ at intervals of 600 mm, and attaching 12 mm thick plywood with 8-d size pegs at intervals of 150 mm. The type of traditional building wall was classified and showed the moment resistance ability of each wall type. This value is expressed as a proportional value divided by the moment resisting capacity of the standard size shear walls not divided into the divided small frames. Although some frames have proportional values larger than 1.0 even though they have openings, most of them show values smaller than 1.0. Also, even without the openings, it showed a smaller value than 1, such as 0.84 and 0.67.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.574-584
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• 2006

Bi-directional loading test data are available to evaluate the design parameters which reflect the characteristics of a construction method and the variations of ground at the site where drilled shafts are installed. The method to obtain the design parameters of a real bridge by hi-directional loading test was introduced. The plans of multi-level testing and installation of measuring instruments should be made according to the rough estimation of axial bearing capacity, the length of pile, and the construction method. While the relationship between end bearing resistance and displacement was obtained directly from the hi-directional loading test, the relationship between unit side resistance and displacement was calculated through the measuring values. 1% displacement of pile diameter was adopted as the criteria of failure for ultimate resistance. As the settlement of pile head at the total ultimate bearing capacity obtained from these method was less than 1.5 % of pile diameter, this method was conservative to use in the field.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.842-847
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• 2008

Despite of the increasing number of the application of the drilled shaft pile in construction site, most of the study of pile capacity has been centered side shear resistance. But it is common that the drilled shaft is socketed on the rock so as to use the bearing resistance, so prediction of the toe's movement and characteristic of the bearing capacity is important as the side shear resistance. Therefore the model tests were performed in order to study the characteristic of bearing capacity on rock mass. The material of the test blocks were the mortar which was mixed with sand, cement and water, and test block size was $240{\times}240{\times}240mm$. Load was pressed by the 45mm of diameter of miniaturized pile and plate jack and steal plate were used to the confined stress for representing the underground condition. The relation of load-displacement was measured in many different conditions of rock mass such as direction of discontinuities, spacing and strength, and q-w curves of the toe of the pile were verified in each condition.

• Journal of IKEEE
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• v.23 no.2
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• pp.580-585
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• 2019

Batteries are being used in ESS, electric vehicles and uninterruptible power backup systems. Lead-acid batteries are the most used batteries for high capacity power back up equipment due to their high reliability and low price advantages. It is very important to estimate the chargeable capacity(SoH), and many algorithms were proposed to estimate the internal resistance of the battery. In this paper, the Battery Monitoring System(BMS) for high capacity uninterruptible power supply for IDC is proposed. A simple algorithm for estimating internal resistance was proposed. An computational block diagram of the proposed signal processing algorithm and BMS system configuration of CPU and analog circuit were shown. The proposed method was proved useful by presenting data examples of application to actual IDC sites.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1079-1083
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• 2009

In this study, the pullout resistance characteristic of a wedge-shaped soil nail, made by attaching small steel sticks to the tip of a nail in a wedge shape, was investigated. It was developed to improve the overall pullout resistance capacity of the existing soil nail system, composed of nail and grout, by making the wedge provide additional pullout resistance. In order to evaluate the pullout resistance of the wedge shape-soil nail, field pullout tests were conducted, and the results were compared with those for the existing soil nail without the wedge. The field test results showed that the pullout resistance capacity of the wedge-shaped soil nail was 50% larger than that of the existing soil nail without the wedge.