• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.211-221
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• 2003

At Aspo hard rock laboratory in Sweden, an in-situ heater experiment called "$\"{A}"{s}"{p}"{o}$ Pillar Stability Experiment (APSE)" is prepared to assess capability to predict spatting and stability in a rock mass between deposition holes for radioactive waste. To Predict reasonably fracturing process at rock pillar under a planned configuration before testing, a boundary element code FRACOD has been applied for modelling. The code has been improved to simulate explicitly fracture evolution both at rock boundaries and in intact rocks. A new inverse stress reconstruction technique using boundary element has been also developed to transfer stress field by excavation and thermal loading into the FRACOD model. This article presents the results from predictive modelling far the planned in-situ test condition. Excavation induced stresses might cause slight fracturing in the pillar walls. Typical shear fractures have been initiated and propagated near central pillar walls during 120 days of heating, but overall rock mass remained stable under the considered configuration. The effects of pre-existing joints and properties of fractures are also discussed. It is found from the results that FRACOD can properly model essential rock spatting and propagation at deep tunnels and boreholes.at deep tunnels and boreholes.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.273-283
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• 2003

Fissured rock and soft ground always suggest, problems in the construction of the underground space. The stress release of the weak underground material by opening the underground space with a soft ground, fissures and joints can lead to the failure of the opening. Grouting of the weak rock and the soft ground, which is a process of injecting some bonding agents into the soft ground, is one of the measures to reinforce the soft ground and to prohibit the failure of the underground construction due to the stress release. The proper installation of the grouting is essential to ensuring the safety of the tunneling operation, so that the evaluation of the grouting performance is very significant. The general procedure of evaluating the grouting is coring the grouted section and measuring the compression strength of the core. However, sometimes when the grouted section is at the crown of the tunnel and the grouting is installed at a wide section, the coring is not good enough. This study is oriented to propose a new and a non-destructive procedure of evaluating the grouting performance. The proposed method is based on the wave propagation of elastic waves, and evaluates the shear stiffness of the ground and investigates the anomalies such as voids and cracks. The SASW ( Spectral-Analysis-of-Surface-Waves) method is one of the candidate s to make the inspection of the pouting performance, and is adopted in this study. The practical grouting activity was monitored by SASW method, and the proposed method was applied to the inspection of the grouting performance to check the verification of the proposed method.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.207-216
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• 2003

To evaluate the smear zone caused by the drain installation, 10 piezometers were installed in the typical soft ground in the western coastal area of Korea. The dynamic pore water pressure developed during the drain installation was monitored using piezometers installed at a distance of 10cm, 20cm, 30cm, 40cm and 50cm from the location of the drain. The decay of pore pressure with time after pushing piezometers to depths of 5 meters and 7 meters during the drain installation was monitored to assess flow and consolidation characteristics of the soil after disturbance of the soil due to the drain installation. The drain installation results in shear strain and displacement of the soil and it decreases the permeability of the soil. Hence, the comparison between dissipation of the pore water pressure process in 10 pieszometers before as well as after installation of the drain indicated the diameter of disturbance zone and smear zone, which is related to the cross-sectional dimension of the mandrel. In addition, Cone-pressuremeter(CPM) tests were performed to obtain rigidity index of the soil for an interpretation of the dissipation processes. It has been evaluated by in-situ tests that the smear zone is from 3.0 to 3.6 times of the cross-sectional dimension of the mandrel. The hydraulic conductivity expressed in terms of the coefficient of consolidation after the drain installation was calculated from 3 to 8 times decrease evaluated by Teh & Houlsby equation and CPM test results.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.158-164
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• 2008

This study was conducted for raising the considering the dynamical context of mobile phone use environment in the mobile-phone research. For this I identified the characteristic of the mobile phone use. The first characteristic is that the mobile phone is the context sensitive device. Also, it reflects the user's life pattern because it is the very personal device. I defined the context of mobile phone use with the basis on this identification of those characteristics. I referenced the definition, 'situational context', defining the mobile phone use context. Also, I set up the research scope within the user task that is influential from the situational context, I named this kind of task as the 'contextual task'. I developed the Contextual Task Model in this study. I named the model as the 'ESR Model'. The reason that I developed this contextual task model is that this model can help novice designers and designers unfamiliar with an application domain understand the user behavior and user centered design. And also this model can be effective to communicate each other, I identified the user's contextual tasks three kinds of model. First, the Extend Model includes user tasks that related to extending from user physical working space to the virtual level. Second model is Synchronize Model, which includes issues that lesson the blocking when use several functions at a time or sequentially. Third model is Replace Model, which is come from the characteristic of user life pattern to use the mobile phone. Finally, I proposed an application of this model, CIQ. Through the process to make CIQ I proved the effectiveness of this ESR Model.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.30-35
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• 2008

The purpose of this study is to analyze and define user's emotional satisfaction factors to the PC OS GUI image. The study is to investigate the relationship between PC OS GUI Image and Sensitive Vocabula교 based on user's emotional preference. 47 user preferred sensitive words are collected by the initial survey. Through the similarity test, 47 words are narrowed down to 20 comprehend words. The semantic differential methods is used in the final survey with 5 step questionnaire. From this process, user preferred the GUI design that is vocabularized as Clear, Easy, Safety, Stability. Additionally, the result shows that the image of Clear is related to Safety and the image of Easy is related to Stability. The result of the study could be used in design PC OS GUI as base data.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.430-435
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• 2008

Thanks to the development of IT technology, there have been developed a variety of types of portable music players. IT technology didn't stop there, however. It has gone to developing GUIs (Graphic User Interfaces) to deliver more information to the user. As the function of GUIs has become important, the music players are being required to show characteristics of the sounds they output visually beyond just delivering the sounds through analyzing the information that the sounds contain. To visualize the information of sounds, that is to say, has become substantial. In this process, sound graphic equalizers have been developed in order. The object of this study is to produce a new sound graphic equalizer with new forms of expressing visual images of sounds besides the bar graphs, in which user feedback is possible. This study has devised a new sound visualization form in visually expressing the information of sounds by analyzing their characteristics. This new sound visualization provides a sound graphic equalizer with which the user can select images for the information of the sounds s/he listens. This study suggests a new alternative GUI with which the user can change the form of the outputted images in realtime as communicating with the player.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.453-460
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• 2004

To prevent penetration of rainwater into the landfill site is the main purpose of the final cover in landfill sites. Conventional designs of landfill covers uses geotextiles such as geomembrane and GCL, and clay liners to lower the permeability of final covers of landfill sites. However, differential settlement and the variation of temperature in landfill sites cause the development of cracks or structural damage inside the final cover and it is also difficult to obtain clay - the main material of the compacted clay liner in Korea. Thus the former final cover system that suggests geomembrane and GCL or compacted clay liner has several limitations. Therefore, an alternative method is necessary and one of them is the application of SRSL(self-Recovering Sustainable Liner) material. SRSL is two different layers consist of individual materials that react with each other and form precipitates, and with this process lowers the permeability of the landfill final cover. SRSL generally is made up of two layers, so that when a internal crack occurs the reactants of the two layers migrate towards the crack and heal it by forming another liner. In this study the applicability of SRSL material for landfill final cover was examined by performing; (1) jar test to verify the formation of precipitate in the mixture of each reactants, (2) falling head test considering the field stress in order to confirm the decrease of permeability or prove that the hydraulic condctivity is lower than the regulations, (3) compression tests to judge weather if the strength satisfies the restricts for landfills, (4) freeze/thaw test to check the applicability of SRSL for domestic climate. In addition, the application of waste materials in the environmental and economical aspect was inspected, and finally the possibility of secondary contamination due to the waste materials was examined by performing elution tests.

• Journal of the Korean housing association
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• v.21 no.1
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• pp.67-77
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• 2010

Citizen participation in local redevelopment has recently been regarded as essential, since progress in democracy and diversified public interests have contributed to more importance being placed on citizen participation in the implementation of public policies. While the importance of resident participation has been increasingly emphasized in principle, in reality more effort is still required in its application. We need to develop practical strategies of collecting community opinion in order to reflect it in public policy, if we are to achieve a resident and citizen-centered society. The purpose of this study is to develop an image map construction tool that can be applied to the "Maul-Mandulgi" projects as a visualized method to facilitate the exchange of opinions and work toward agreements. The tool is intended to assist public discussion by visualizing policies and plans and reducing the possibility of misunderstanding, so that residents can properly respond to the plans. Second, this study will verify the effectiveness of the tool in the application to local community workshops. The main research method is participant observation method and field study. Major findings are as follows, First, every resident who had participated in previous workshops gathered together, used the tool and represented their opinions unusually more than once. Each resident tried to make sure that other participants appropriately understood his or her opinion. The workshop finished when all participants agreed and produced a consensus. The workshop took much less time, which is in stark contrast to previous workshops in which it took significantly more time to collect opinions. Second, it proved that residents in the redevelopment area can strike a broad agreement by themselves on a method and direction for residential improvement. In previous workshops, conflicts between residents developed over the choice between the two methods, of local improvement and total demolition prior to multi-housing construction. In this study, opinions of residents were not limited to the two methods by finding a winwin solution. Third, the use of the tool kit for image map became efficient for inactive residents to develop their own opinions in regard to the direction and orientations of the residential improvement process. In addition, for those who have either no or a slight understanding of the residential improvement projects, the tool can provide access to information and knowledge. This study concludes that the developed tool for imaging of the redevelopment projection like a design game, rather than using forms of text and speech, can be a useful tool in collecting opinions and forming an agreed opinion for forthcoming residential improvement plans.

• Journal of the Korean Geotechnical Society
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• v.31 no.8
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• pp.51-62
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• 2015

It is not possible to provide resonable evidence for embankment (or dam) overtopping in geotechnical engineering, and conventional analysis by hydrologic design has not provided the evidence for the overflow. However, hydrologic design analysis using Copula function demonstrates the possibility that dam overflow occurs when estimating rainfall probability with rainfall data for 40 years based on fluctuating water level of a dam. Hydrologic dam risk analysis depends on complex hydrologic analyses in that probabilistic relationship needs to be established to quantify various uncertainties associated with modeling process and inputs. The systematic approaches to uncertainty analysis for hydrologic risk analysis have not been addressed yet. In this paper, the initial level of a dam for stability of a dam is generally determined by normal pool level or limiting the level of the flood, but overflow of probability and instability of a dam depend on the sensitivity analysis of the initial level of a dam. In order to estimate the initial level, Copula function and HEC-5 rainfall-runoff model are used to estimate posterior distributions of the model parameters. For geotechnical engineering, slope stability analysis was performed to investigate the difference between rapid drawdown and overtopping of a dam. As a result, the slope instability in overtopping of a dam was more dangerous than that of rapid drawdown condition.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.175-180
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• 2011

In this study, the $TiO_{2}/V_{2}O_{5}$ hybrid semiconductors were prepared by mixing $TiO_{2}$ and $V_{2}O_{5}$, and a subsequent smash process to reduce the recombination of electron and improve the efficiency of solar cells. Dye-sensitized solar cells were constructed using the resultant hybrid semiconductor, and their electrochemical properties were also investigated. The photocurrent-voltage curve obtained with the cells indicated a significant increase in the efficiency from 2.9 to 5.7% by the factor of 2 compared to the result obtained only with $TiO_{2}$. It is believed that the introduction of $V_{2}O_{5}$ effectively transport electrons in the $TiO_{2}$ conduction band to FTO glass and suppress recombination with the dye and/or the electrolyte, thus yielding an efficient performance of the dye sensitized solar cell. The impedance values also indicated a decrease of resistance in the interface of $TiO_{2}$/dye/electrolyte supporting the constructive contributions of the smashed $TiO_{2}/V_{2}O_{5}$ hybrid semiconductors for the efficiency.