• KSTLE International Journal
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• v.1 no.1
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• pp.48-51
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• 2000

Surface damage accumulation of alumina ceramics under the cyclic stress state was analyzed. The alternating stress state in repeat pass sliding contact was simulated by a synchronized biaxial (normal and tangential) repeated indentation technique. Wear debris formation mechanism through damage accumulation and fatigue grain failure in both alumina ceramic balls and flat disks was confirmed, and the contact induced surface degradation due to fatigue cracking accumulation was quantified by measuring vertical contact displacement. Variation of structural compliance (slope of load-displacement curve) of two contacting bodies was expressed as a variation of the apparent elastic property, called pseudo-elastic constant, of the contact system.

• The Korean Journal of Ceramics
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• v.4 no.4
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• pp.356-362
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• 1998

Hertzian crack suppression phenomena and relatively high damage tolerance were investigated in hard/soft silicon nitride ($Si_3N_4$) bilayers. Coarse $\alpha}-Si_3N_4$ powder was wsed for the hard coating layer and fine $\alpha}-Si_3N_4$ powder was used for the soft substrate layer. The two layers were designed with a strong interface. Hertzian indentation was used to investigate contact fracture and damage tolerance property. Hertzian crack suppression has occurred with increasing applied load and decreasing coating thickness. The crack suppression contributed strength improvement, especially in the bilayers with thinner coatings. Ultimately, the combination of hard coating with soft but tough underlayer improved the damage tolerance of brittle $Si_3N_4$ ceramics.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.190-195
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• 2008

Surge proof equipment is an installation to make surge flow on the ground promptly so as to reduce surge-related damage on infrastructure, not to prevent surge from falling down on infrastructure directly. Compared with classical line individual earth, High speed line common earth has higher surge characteristic and plays a significant role to prevent infrastructure damage and injuries from surge, or short circuit accident between 25kV catenary and rail. In this paper, we analyzed the case of accident that caused communication/signaling system impaired while a tractor crossing level crossing at Honam line; in addition, we examined the accident reduction measures to minimize injury and property damage from cutting accidents with respect to common earth network.

• Journal of the Korean Ceramic Society
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• v.56 no.1
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• pp.77-83
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• 2019

MgO-C refractories are used in basic furnaces and steel ladles due to their many desirable properties, such as excellent thermal shock resistance via low thermal expansion, and high thermal conductivity. However, the mechanical and thermal properties of the refractory continuously deteriorate by spalling phenomena and pore generation due to the oxidation of graphite, used as a carbon source, indicating that the characteristics and performance of MgO-C refractories need to be improved by using a new material or composition. In this study, the use of a Hertzian indentation test as a method for determining the damage and fracture behavior of an MgO-C refractory is described. The results highlight that Hertzain indentation tests can be one of the important evaluation tools for quasi-plastic damage accumulation of MgO-C refractories during falling process of scrap metal.

• Journal of the Korean Society of Safety
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• v.31 no.2
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• pp.127-132
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• 2016

In this study, the plan to construct a disaster information categorization system that can be objectively and efficiently performed was suggested in order to perform disaster management task systematically. Recently, the damage of natural disasters is gradually growing larger and faster, increasing the economic loss. Especially, as for the domestic storm damage, the damage from strong wind was found to be greater than the damage from torrential rain. Also, strong wind was found to be inflicting a great damage on human life, property and agricultural crops, so the necessity to study damage restoration from strong wind is increasing. Nevertheless, the damage items categorized in the domestic disaster year book are often comprehensive or unclear in criteria, and thus fail to reflect items or matters due to actual disaster damage. It is difficult to aggregate damage accurately such that it does not correspond to the national compensation scope or the damage amount is calculated according to subjective judgment of the investigator in charge. As such, if the disaster information management is inadequate by not applying accurate categorization criteria from damage amount calculation, there can be an issue with fairness when paying the damage support aid. Therefore, this study suggested a categorization plan for objective and efficient execution of disaster information management task in order to resolve such issues. It is expected that quick and efficient execution would be possible in disaster information management and task procedure domestically by constructing systematic categorization system related to disaster information.

• The Korean Society of Law and Medicine
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• v.20 no.1
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• pp.47-82
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• 2019

Inter-Korean exchanges and cooperation, in the process, will inevitably lead to various legal disputes, one of which is the issue of compensation for personal injury. The purpose of this study is to present the standards of settlement of disputes between the residents of North and South Korea by examining the North Korean compensation law on the calculation of damages due to personal injury and comparing it with the South Korean compensation law. Understanding the North Korean compensation law is a critical and urgent task, as exchanges and cooperation between the two Koreas are expected to increase in the future. For the South Korean compensation law does not have specific provisions on the estimation of damages, the specific methods and standards for estimating damages are determined by court precedents. The South Korean courts categorize the damages caused by personal injury into active property damages, passive property damages and emotional distress damages and calculate the amount of each damages. On the other hand, the North Korean Compensation for Damage Act stipulates the categories of damage by dividing the cases of personal injury into 1) infringement of health(§41), 2) disability due to infringement of health(§42), and 3) death resulting from human infringement(§44). In addition, the North Korea Compensation for Damage Act specifies the calculation of compensation for damages(§43, §51). Furthermore, South Korea widely acknowledges emotional distress damages for personal injury, whereas North Korea does not recognize emotional distress damages in principle.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.4
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• pp.97-106
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• 2016

Since public facilities have high property values and are directly exposed to the flood hazard, they account for the highest share of disaster damages compared to other assets such as housing, industry, vehicle and agriculture in case of floods. Therefore, this study was conducted to develop and suggest the potential flood damage index for public facilities to evaluate potential flood damage of specific local government directly or indirectly as a tool for decision-making related to flood prevention, maintenance, management, and budget allocation. The flood damage assessment system proposed in this study was evaluated in 231 local governments nationwide. Evaluation results showed that higher values were obtained in Seoul metropolitan government, Gyeonggi-do (province), coastal areas in Gyeongsangnam-do (province), and Jeju island.

• Interaction and multiscale mechanics
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• v.2 no.2
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• pp.153-175
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• 2009

Damage detection methods using structural dynamic responses have received much attention in the past decades. For bridge and offshore structures, these methods are usually based on beam models. To ensure the successful application of these methods, it is necessary to examine the sensitivity of modal properties to structural damages. To this end, an analytic solution is presented of the modal properties of simply-supported Euler-Bernoulli beams that contain a general damage with no additional assumptions. The damage can be a reduction in the bending stiffness or a loss of mass within a beam segment. This solution enables us to thoroughly discuss the sensitivities of different modal properties to various damages. It is observed that the lower natural frequencies and mode shapes do not change so much when a section of the beam is damaged, while the mode of rotation angle and curvature modes show abrupt change near the damaged region. Although similar observations have been reported previously, the analytical solution presented herein for clarifying the mechanism involved is considered a contribution to the literature. It is helpful for developing new damage detection methods for structures of the beam type.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.31-34
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• 2005

For the damage tolerance improvement of conventional laminated composites, stitching process has been utilized for providing through-thickness reinforcements. 2D prefonl1S were stacked with S-2 glass plain weave, and 3D preforms were fabricated using the stitching process. For the matrix system, epoxy and phenol resins were considered. To examine the damage resistance performance the low velocity drop weight impact test has been carried out, and the impact damage was examined by scanning image. CAI (Compressive After Ih1paet) tests were also conducted to evaluate residual compressive strength. Compared with 2D epoxy composites, 2D phenol composites showed drastic reduction in the compressive strength prior to impact because of the higher contents of voids. The damage area of 2D phenol composites were also larger than that of 2D epoxy composites. However, by introducing the stitching, the damage area of 3D phenol composites was reduced by 60%, while the CAI strength improvement was negligible.

• Earthquakes and Structures
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• v.13 no.4
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• pp.387-396
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• 2017

The first determination and assessment of the damages to structures after the earthquake is important for preventing increase in loss of life and property that may occur in later times. When rapid damage assessment is performed after an earthquake, damage assessment forms are generally used. The forms that are filled in the field are assessed in the office environment later. In this study, while the process of earthquake damage assessment was being carried out, the ready-made form was moved to web base and the data to be obtained in the field was transferred to the database by means of tablets and smart phones. Keeping earthquake damages in a database will contribute to the studies to be conducted on earthquake and the earthquake regulations to be prepared. Furthermore, emergency damage assessment will be performed faster and more reliably after the earthquake through this study. As the data transferred to the web base is accessible to different people, savings will be provided for both time and personnel. Furthermore, the assessment will have a healthier and scientific basis. In this study, exemplification was conducted for six different reinforced concrete buildings that were damaged during Van earthquake in October 23. With this study, damage assessment procedures can be completed as soon as possible.