• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.109-120
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• 2017

Groundwater seepage into a tunnel is one of the main causes triggering tunnel collapse and the consequent ground subsidence. Thus, it is important to estimate adequately the groundwater inflow rate and porewater pressure change during tunneling with time elapse. In current practice, Goodman's analytical solution (or image tunnel method) assuming homogeneous ground condition around a tunnel is commonly used for estimating groundwater inflow rate. However, the generally-used analytical solution for estimating groundwater inflow rate does not consider groundwater level drawdown and permeability change with depth, and the inflow rate can be overestimated in design phase. In this study, parametric study was performed in order to investigate the effect of groundwater level drawdown and permeability reduction with depth, and transient flow analysis was carried out for studying the inflow rate change as well as groundwater level and porewater pressure change around a tunnel with time elapse.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.9
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• pp.273-282
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• 2023

Recently, various technologies such as logistics automation and port operations automation with ICT technology are being developed to build smart ports. However, there is a lack of technology development for port safety and safety accident prevention. This paper proposes an AI-based shipping container loading safety management system for the prevention of safety accidents at container loading fields in ports. The system consists of an AI-based shipping container safety accident risk classification and storage function and a real-time safety accident monitoring function. The system monitors the accident risk at the site in real-time and can prevent container collapse accidents. The proposed system is developed as a prototype, and the system is ecaluated by direct application in a port.

• The Southeast Asian review
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• v.28 no.3
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• pp.213-261
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• 2018

On May 9, 2018, regime change took place in Malaysia. It was the first regime change that took place in 61 years after independence in 1957. The regime change was an unexpected result not only in Malaysian experts but also in political circles. Moreover, the outcome of the election was more shocking because the opposition party was divided in this general election. The regime change in Malaysia was enough to attract worldwide attention because it meant the collapse of the oldest regime in the modern political system that exists, except North Korea and China. How could this have happened? In particular, how could the regime change, which had not been accomplished despite opposition parties' cooperation for almost 20 years, could be achieved with the divided opposition forces? What political implications does the 2018 general election result have for political change and democratization in Malaysia? How will the Malaysian politics be developed in the aftermath of the regime change? It is worth noting that during the process of finding answers, a series of general elections since the start of reformasi in 1998 tended to be likened to a series of "tsunami" in the Malaysian electoral history. This phenomenon of tsunami means that, even though very few predicted the possibility of regime change among academia, civil society and political circles, the regime change was not sudden. In other words, the regime in 2018 was the result of the desire and expectation of political change through a series of elections of Malaysian voters last 20 years. In this context, this study, in analyzing the results of the election in 2018, shows that the activation of electoral politics triggered by the reform movement in 1998, along with the specific situational factors in 2018, could lead to collapse of the ruling government for the first time since independence.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.670-677
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• 2007

The stability of CGAs(colloidal gas aphrons) prepared from non-ionic and ionic surfactants was investigated. Those surfactants were sodium dodecyl sulfate(SDS), Triton X-100, Tween 80 and Quillaja Saponin. The stability of CGAs prepared from single surfactants or mixed surfactants(two components) using a CGA generate. was investigated as functions of temperature, surfactant concentration and stirring time. Saponin among the single surfactants has shown the longest duration time(143 min) and then, Triton X-100, SDS, and Tween 80 were followed by at room temperature. In case of CGAs heated up to $70^{\circ}C$, SDS endured for 116 min but Saponin lasted for only 105 mit which was a considerable reduction of the duration time of CGAs at room temperature. For mixed surfactant pairs, stability of any one pairs stood between the two. That meant no synergic effect for surfactant blending. At the higher temperature, Saponin+Triton X-100 was disclosed to be the lowest, 53 min meanwhile Saponin+SDS was the highest at ambient temperature. The CGAs, initially about 140 ${\mu}m$ in diameter, began to grow right after the agitation to be about 190 ${\mu}m$ owing to coalescence of the bubbles and then became to collapse. When heated, CGAs including Saponin tended to be smaller while the others to be larger. In summary, we found that the stability of CGAs or the duration time was greater for single surfactants and at room temperature rather than for mixed surfactants that caused substantial intermolecular interactions in the CGA structure and at the higher temperature.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.174-181
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• 2018

This paper examines the structural behavior of 3D printed concrete specimens with focus on the bond between the layers. The tensile bond and flexural strengths were investigated experimentally and compared with those of specimens made by conventional mold casting. The test parameters were the time gap between printing layers and the reinforcement between vertical layers. The results showed the 3D printed specimens had voids between layers and confirmed the strength reduction due to printing time gap and the stress concentration caused by the voids. Most of the reduction in tensile bond strength between layers was due to the stress concentration at least up to certain printing time gap. Moreover, beyond a certain printing time gap (24hours), the additional reduction in tensile bond strength reached a level that could affect the structural behavior. The reinforcement between layers was helpful to increase the ductile behavior which is essential to prevent the sudden collapse of the structure. In addition, the reduction in flexural strength due to the stress concentration by the voids was observed and should be considered in the design of 3D printed wall structures against the lateral load.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.2
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• pp.21-26
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• 2015

Mesoporous ceramic materials were applied in various fields such as adsorbent and gas sensor because of low thermal conductivity and high specific surface area properties. This structure could be divided into open-pore structure and closed-pore structure. Although closed-pore structure mesoporous ceramic materials have higher mechanical property than open-pore structure, it has a restriction on the application because the increase of specific surface area is limited. So, in this work, specific surface area of closed-pore structure $TiO_2$ was increased by anneal time. As increased annealing time, crystallization and grain growth of $TiO_2$ skeleton structured material in mesoporous structure induced a collapse and agglomeration of pores. Through this pore structural change, pore connectivity and specific surface area could be enhanced. After anneal for 24 hrs, porosity was decreased from 36.3% to 34.1%, but specific surface area was increased from $48m^2/g$ to $156m^2/g$. CO gas sensitivity was also increased by about 7.4 times due to an increase of specific surface area.

• The Journal of Fisheries Business Administration
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• v.34 no.1
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• pp.137-156
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• 2003

Increasingly, leisure time is being used for outdoor recreational activities, and fishing is one of the principal forms of marine recreation. Marine recreational fishing is a popular activity in Korea and this activity has led to the development of a sector of substantial social and economic value. Also it is considered as one of the important outdoor leisure industries in Korea. With rising of income level and development of marine outdoor leisure industries, social, economic demand increase of marine recreational fishing are showing us new advance ability of marine aquatic bio-industry. However the recreational use of fish stocks has become an important consideration in the public and environmental economic analysis of management aspect of fishing, having grown considerably over recent years to reach a level in Korea where the fish stocks and coastal ecosystem has become a significant management problem. we are inevitably facing marine environmental deterioration and overfishing in marine recreational fishing. In this study, not only resources and environmental problems which are occurred by recreational fishers, but also illegal fishing behaviors and other problems such as market's failure are going to analyze basic management theories and methods of recreational fishing through mathematical principals and economic rents which maximize net social benefits. In view of the likelihood of marine recreational fishers adopting high rates of discount, the conservation of fish resources would appear to require continual public surveillance and control of the physical yield and condition of the fish stocks and the optimal use level. The institutional management of recreational fisheries is the way of escaping the collapse of recreational fisheries just like as the situation of management's failure of commercial fisheries worldwide. One of the effective management measure is a license system. In this system, optimal fee is paid by recreational fishers, which prevent them from overfishing, environmental problems to some extents and carry out the optimal number of outings. And money obtained by license fee should be spent for more improvement fishing culture and welfare for marine recreational fishing. Marine recreational fishing is to be promoted under sound conservation and management principles.

• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.95-101
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• 2016

This study proposes a multi-scale dynamic system reliability analysis of control system as a method of quantitative evaluation of its performance in probabilistic terms. In this second paper, we discuss the control effect of the viscous damper on the seismic performance of the structure-level failure. Since the failure of one structural member does not necessarily cause the collapse of the structural system, we need to consider a set of failure scenarios of the structural system and compute the sum of the failure probabilities of the failure scenarios where the statistical dependence between the failure scenarios should be taken into account. Therefore, this computation requires additional system reliability analysis. As a result, the proposed approach takes a hierarchial framework where the failure probability of a structural member is computed using a lower-scale system reliability with the union set of time-sequential member failures and their statistical dependence, and the failure probability of the structural system is again computed using a higher-scale system reliability with the member failure probabilities obtained by the lower-scale system reliability and their statistical dependence. Numerical results demonstrate that the proposed approach can provide an accurate and stable reliability assessment of the control performance of the viscous damper system on the system failure. Also, the parametric study of damper capacity on the seismic performance has been performed to demonstrate the applicability of the proposed approach through the probabilistic assessment of the seismic performance improvement of the damper system.

• The Plant Pathology Journal
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• v.34 no.1
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• pp.78-84
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• 2018

Peroxyacetic acid mixture Perosan, composed of peroxyacetic acid, hydrogen peroxide and acetic acid, was evaluated for eco-friendly management of tomato bacterial wilt by Ralstonia pseudosolanacearum. Perosan drastically suppressed in vitro growth of R. pseudosolanacearum in liquid cultures in dose- and incubation time-dependent manners. Higher perosan doses (0.1 and 1%) caused lowered pH and phytotoxicity to detached leaves of two tomato cultivars Cupirang and Benekia 220 in aqueous solution. Treatment with 0.01% of Perosan delayed wilting symptom significantly in the detached leaves of two cultivars inoculated with R. pseudosolanacearum ($10^7cfu/ml$). Soil drenching of 5% Perosan solution in pots caused severe tissue collapse of tomato seedlings at the four-week-old stage of two tomato cultivars. Treatment with 1% Perosan by soil-drenching significantly reduced bacterial wilt in the tomato seedlings of two cultivars. These findings suggest that Perosan treatment can be applied to suppress bacterial wilt during tomato production.

• Archives of Reconstructive Microsurgery
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• v.15 no.2
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• pp.101-106
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• 2006

The purpose of this study was to analyze the mid to long-term clinical and radiological outcome of vascularized pronator quadratus-wrapped radial bone flap arthroplasty for symptomatic advanced $Kienb{\ddot{o}}ck's$ disease. Between 1982 and 2000, 41 cases of advanced $Kienb{\ddot{o}}ck's$ disease were treated with vascularized pronator quadratus wrapped radial bone flap arthroplasty. There were 17 men and 24 women, with a mean age of 39 years at the time of operation. According to Lichtman's classification, there were 13 stage IIIb and 28 stage IV patients. The duration of follow-up averaged 6.1 ($3{\sim}22$) years. We assessed the clinical outcome by subjective pain and active range of motion of the wrist, and evaluated the radiologic outcome by using carpal height ratio and radioscaphoid angle. Postoperatively, all patient reported an improvement in their symptoms. The mean active extension and flexion were improved by $9^{\circ}$ and $6^{\circ}$, respectively (p<0.05). The carpal height ratio was decreased from a mean of 0.52 to 0.48, and the radioscahpoid angle was increased from a mean of $61^{\circ}$ to $66^{\circ}$, but the differences were not significant statistically. Vascularized pronator quadratus-wrapped radial bone flap arthroplasty improves the wrist motion and may prevent serious carpal collapse in advanced $Kienb{\ddot{o}}ck's$ Disease.