• Journal of the Korean Society of Safety
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• v.32 no.4
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• pp.34-39
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• 2017

Typical flow regime of overflow at barrier or weir constructed in mid and small streams becomes as the submerged flow during most flood events. One of major causes of barrier failure has been reported as the levee-scour near the conjuction node between barrier and levee. However, most related design guidelines in Korea have not mentioned about the protection of levee around barrier or weir in detail. Furthermore, most previous researches have focused on the flow characteristics of overflow around several types of weirs but they did not have considered the material properties of levee itself. In this study, local scour near barrier was investigated with different material properties of levee under the submerged overflow condition which is assumed to reenact a flood event. Based on results from Fritz et al. and Mavis et al., a theoretical formula was also proposed in initial stage of laboratory experiments. And hydraulic experiments were carried out for the verification of the proposed formula. Levee was installed in the prismetic trapezoidal open channel and most parts were made of concrete except for movable section in which scour was expected to occur for the efficiency of experimental procedure. Each compaction of movable section in levee was followed by the basis of the KS F 2312. Further, after performing the experiments to find the optimum water content for each sediment, the specific amount of water was injected before flowing water. The difference between the proposed theoretical formula and experiment results was not much but considerable, which might be caused by the effect of compaction. For theoretical approach, it seemed that the formula did not take into account the compaction of levee, thus the correction coefficient for levee compaction determined in the literature was considered. Finally, the formula for the length of scour around barrier or weir was proposed, which can be useful to predict a levee in the reference design of revetment in mid and small streams. As shortly future study, scour length of levee around barrier or weir under different flow conditions such as perfect overflow condition will be studied and it will be able to contribute to suggest the design formula or criteria under all overflow conditions near barrier or weir.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.3
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• pp.178-192
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• 2006

The buffer overflow attack is the single most dominant and lethal form of security exploits as evidenced by recent worm outbreaks such as Code Red and SQL Stammer. In this paper, we propose microarchitectural techniques that can detect and recover from such malicious code attacks. The idea is that the buffer overflow attacks usually exhibit abnormal behaviors in the system. This kind of unusual signs can be easily detected by checking the safety of memory references at runtime, avoiding the potential data or control corruptions made by such attacks. Both the hardware cost and the performance penalty of enforcing the safety guards are negligible. In addition, we propose a more aggressive technique called corruption recovery buffer (CRB), which can further increase the level of security. Combined with the safety guards, the CRB can be used to save suspicious writes made by an attack and can restore the original architecture state before the attack. By performing detailed execution-driven simulations on the programs selected from SPEC CPU2000 benchmark, we evaluate the effectiveness of the proposed microarchitectural techniques. Experimental data shows that enforcing a single safety guard can reduce the number of system failures substantially by protecting the stack against return address corruptions made by the attacks. Furthermore, a small 1KB CRB can nullify additional data corruptions made by stack smashing attacks with only less than 2% performance penalty.

• Journal of Korea Water Resources Association
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• v.41 no.1
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• pp.65-74
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• 2008

The small and medium sized dams have the fill dam type of a lot of occasions, which are often weak in cases of major floods. For this reason, although a countermeasure is in great need, due to the importance of the facilities and financial situations, no direct safety measures have been taken. In this study, in order to minimize construction expenditure for practical safety measures in cases of major floods, the overflow section of spillway has been analyzed focusing on how the overflow capacity will increase in the case of partially rebuilding a part of the overflow section of spillway favorable for hydraulic conditions. The Labyrinth weir and movable weir was chosen for reconstruction models of the overflow section. Moreover, for analyzing the after-effects of the reconstruction, a small scale dam was temporarily chosen for various experiments such as the hydraulic model testing and the three dimension numerical evaluation through the use of Flow-3D.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.413-418
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• 2001

Emergency shut-on valve was developed to shut off natural gas at the front of a gas meter in the house. The shut-off flow rate and differential pressure of this valve was controlled by adjusting the distance between the spool and magnet. Also the spool shape was an important factor in the performance of this valve. The experimental and computational results will be useful for the design having better performance.

• Journal of the FoodService Safety
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• v.2 no.2
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• pp.103-110
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• 2021

This study was conducted to compare and evaluate the difference in washing and disinfection when the Hazard Analysis and Critical Control Point (HACCP) protocol was applied to foodservice operations. The results of the survey were as follows: Among the 116 foodservice operations surveyed, 67.2% were HACCP-compliant and 32.8% were not HACCP-compliant. Also, 62.9% served meals once daily, and 79.3% conducted food safety education once a month. Compared to HACCP non-compliant foodservice operations, the disinfection performance of HACCP-compliant operations was significantly better concerning worktables (p<0.001), food inspection tables (p<0.001), preparation tables for distribution (p<0.01), serving tables (p<0.01), overflow and trenches(p<0.05), sinks (p<0.05), and insect attracting lamps (p<0.01). Similarly, the disinfection performance of HACCP-compliant foodservice operations was significantly better for 18 cooking utensils and personal tools such as food slicers (p<0.001), multiple cooking machines (p<0.05), tray carts (p<0.001), stainless steel tools (p<0.001), rubber gloves (p<0.05). Worktables (45.1%), serving tables (29.6%), sinks (37.0%), and scales (21.6%) were most often disinfected 'at the end of each task', while food inspection tables (36.5%), food preparation tables for distribution (31.2%), dish machines (34.2%), overflow and trenches (25.7%), and floors (25.8%) were most often disinfected 'once a day'. All cooking utensils were most often disinfected 'at the end of each task'. 'Chemical disinfection' was most frequently used in all foodservice facilities. To improve the food safety management of foodservice operations, it is necessary to apply the HACCP protocol and comply with the washing and disinfection manual.

• Journal of Korea Water Resources Association
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• v.51 no.4
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• pp.371-381
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• 2018

Domestic agricultural reservoir dam facilities are difficult to manage water resources because of the in summer rainfall increase due to aging and climate change, it is expected that the dam risk will be large due to the overflow. In this study, author selected study basin in order to evaluate hydrological safety of agricultural reservoir dam facilities. And calculated the probable rainfall, Present PMP, Future PMP considering climate change. Also, author carried quantitative analysis out for increasing rainfall due to climate change, analyze freeboard assessment of agricultural reservoir by calculate flood discharge, reservoir flood routing according to rainfall scenarios. As a result of evaluate hydrological safety of agricultural reservoir dam facilities using Future PMP considering climate change, Gosam, Kumkwang, Miho, Cheongcheon reservoir had the Highest Water Level over the design flood level, it is analyzed that it would be vulnerable to overflow risk.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.2
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• pp.345-351
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• 2023

As software development progresses and programs become increasingly complex, the cost of reducing and managing software vulnerabilities has also increased. To address this issue, the Rust programming language, which guarantees Memory Safety, has been suggested as an alternative for more error-prone languages such as traditional C/C++. However, Rust also supports the use of libraries written in C/C++ to enhance compatibility with older languages and avoid redundant development, compromising its original guarantees. For example, memory corruption happened in C/C++ can lead to exploits such as buffer overflow, Use-After-Free and null-pointer dereferecing. To tackle this problem, recent studies have been conducted to secure interactino between Rust and C/C++ by isolation. This paper uncovers areas that have not been fully explored in previous studies, following limitation analysis on each. Finally, this paper suggests the future direction of research on safe interaction between Rust and C/C++.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6B
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• pp.533-540
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• 2010

Recently management of vegetation distributed in the watercourse is very important not only for safety but also for river restoration. In general, vegetations in the watercourse increase hydraulic resistance and accordingly decrease conveyance capacity which may yield levee overflow. This paper simulates water level rise using 1D and 2D hydro dynamic model to check the possibility of overflow in downstream of the Soyang Reservoir by assigning different roughness coefficient corresponding to different types of vegetation. In this study, 3 different vegetation types of tree, shrub, and main channel were considered and corresponding Manning's roughness coefficient n was assigned based on the vegetation map generated from the site investigation. As results, the water level raised about 0.1 to 0.7 m comparing with the case without considering vegetation and a proper measurements is necessary where overflow occurs due to low level levee.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.132-137
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• 2018

Although the number of chemical accidents has been declining since the Chemical Control Act of 2015, there have been repeated occurrences of similar types of accidents at printed circuit board (PCB) manufacturing facilities. These accidents were caused by the overflow of hydrochloric acid and hydrogen peroxide, which are toxic chemicals used in the printed circuit board manufacturing process. An analysis of the $Cl^-$ content to identify the cause of the accident showed that in the mixed route of hydrochloric acid and hydrogen peroxide, which are accidental substances, the $Cl^-$ concentration was 66.85 ppm in the hydrogen peroxide sample. Through reaction experiments, it was confirmed that the deformation of a PVC storage tank and generation of chlorine gas, which is a toxic gas, occurred due to reaction heat occurring up to $50.5^{\circ}C$. This paper proposes a facility safety management plan, including overcharge, overflow prevention, leak detection device, and separation tank design for mixing prevention in printed circuit board manufacturing facility etch process. To prevent the recurrence of accidents of the same type, the necessity of a periodic facility safety inspection and strengthening of the safety education of workers was discussed.

• Journal of the Korean Society of Safety
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• v.35 no.3
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• pp.1-5
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• 2020

The leakage accident from a storage tank in an oil refinery plant occurred in April 2014 and the total loss is KRW 18 billion. This accident has prompted many companies to develop their own mitigation system to minimize the loss of the leakage accident. The aim of this study is to design the temporary storage facility system for dealing with leakage accidents. The basic concept of this system is that the leakage fluid of a hazardous material flows into a temporary storage tank and this is transferred to a spare tank by a pump as avoiding the overflow of a temporary storage tank. In order to design this system, the leakage velocity and quantity according to time series should be evaluated. In addition, a proper pump capacity should be determined to avoid repeating the pump switching on and off frequently. In this study, the benzene tank is selected to verify the efficacy of this system. This study can play a critical role to provide a guideline for designing a new system.