• Korean Security Journal
• /
• no.5
• /
• pp.309-325
• /
• 2002

It was because mankind could use the fire that we have been civilized. creating a brilliant culture and developing an industrial society. While fire is very useful to our life, the number of the victims of fire continues to increase, This study suggests the ways to rescue the people safely when they are subject to a fire in a high-rise building. To this end, the concept of fire is reviewed. Fire breaks out when the conditions for congestion are met, and therefore. if any of the conditions can be blocked, the fire will be extinguished. In other words. the knowledge of such conditions will greatly help the fire fighters to rescue the people, and so. such conditions for congestion as flammable, heat, oxygen and chain reaction are examined. In addition, the effects of such by-products of fire as heat and smoke on human body are reviewed. In order to rescue the people more safely, the fire fighters are requested to review the situation and design a rescue strategy before being engaged in a full-scale rescue activity. This study discusses various rescue methods using such passages or equipments as stair case, double ladder, special fire fighting vehicle, elevator, jumar, rope, helicopter, etc. In conclusion. since it is more difficult to rescue the people from a high-rise building than from the ground, it is essential to design a rescue program not after fire but before it and thereby, minimize the number of victims.

• Journal of the Microelectronics and Packaging Society
• /
• v.25 no.2
• /
• pp.25-30
• /
• 2018

Sn-Pb solder has been used in automotive electronics for decades. However, recently, due to the environmental and health concerns, some international environmental organizations such as the end-of-life vehicle (ELV) enacted legislation banning of the Pb usage in automotive electronics. For this reason, many studies to develop and promote Pb-free soldering have been significantly reported. Meanwhile, because of flexibility and lightweight, flexible printed circuit boards (FPCBs) have been increasingly used in automotive electronics for lightweight to improve fuel efficiency and space utilization. Although the properties of lead-free solders for automotive electronics have been widely studied, there is a lack of research on the reliability performance of the lead-free solder joint on FPCB under user conditions. This study reported the properties of solder joints between Pb-free solders such as Sn3.0Ag0.5Cu, Sn0.7Cu and Sn0.5Cu0.01Al (Si), and various FPCBs finished with organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG). To evaluate on joint properties and reliabilities with different solder compositions and surface-finishing materials, pull strength test, thermal shock test, and bending cycle test were performed and analyzed. After the bending cycle test of solder joint on OSP-finishing, the fractures were occurred in solder and the lifetime of Sn3.0Ag0.5Cu solder joint was the longest.

• Laboraroty Animal Research
• /
• v.34 no.4
• /
• pp.317-328
• /
• 2018

Cognitive impairment responses are important research topics in the study of degenerative brain diseases as well as in understanding of human mental activities. To compare response to scopolamine (SPL)-induced cognitive impairment, we measured altered parameters for learning and memory ability, inflammatory response, oxidative stress, cholinergic dysfunction and neuronal cell damages, in Korl:ICR stock and two commercial breeder stocks (A:ICR and B:ICR) after relevant SPL exposure. In the water maze test, Korl:ICR showed no significant difference in SPL-induced learning and memory impairment compared to the two different ICRs, although escape latency was increased after SPL exposure. Although behavioral assessment using the manual avoidance test revealed reduced latency in all ICR mice after SPL treatment as compared to Vehicle, no differences were observed between the three ICR stocks. To determine cholinergic dysfunction induction by SPL exposure, activity of acetylcholinesterase (AChE) assessed in the three ICR stocks revealed no difference of acetylcholinesterase activity. Furthermore, low levels of superoxide dismutase (SOD) activity and high levels of inflammatory cytokines in SPL-treated group were maintained in all three ICR stocks, although some variations were observed between the SPL-treated groups. Neuronal cell damages induced by SPL showed similar response in all three ICR stocks, as assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, Nissl staining analysis and expression analyses of apoptosis-related proteins. Thus, the results of this study provide strong evidence that Korl:ICR is similar to the other two ICR. Stocks in response to learning and memory capacity.

• Journal of Welding and Joining
• /
• v.31 no.5
• /
• pp.54-58
• /
• 2013

Joint properties of vehicle ECU (Electric Control Unit) module which was manufactured by using Sn-Cu-Cr-Ca alloy were investigated. A new solder which has a middle melting temperature about $231^{\circ}C$ was fabricated as the type of 300um solder ball and paste type. The prototype modules were made by reflow process and measured spreadability, wettability shear strength and estimated interface reaction. The spreadability of the alloy was about 84% from the measurement of contact angle of the solder ball and the wetting force was measured 2mN. The average shear strength of the module which was manufactured by using the solder paste, was 1.9 $kg/mm^2$. Also, the thickness of IMC(intermetallic compound) was evaluated with various aging temperature and time in order to understand Cr effect on Sn-0.7Cu solder. $Cu_6Sn_5$ IMC was formed between Cu pad and the solder alloy and the average thickness of the $Cu_6Sn_5$ IMC was measured about 4um and it was about 50% of thickness of $Cu_6Sn_5$ IMC in Sn-0.7Cu. It is expected to have a positive effect on reliability of the solder joint.

• Journal of Welding and Joining
• /
• v.34 no.1
• /
• pp.26-34
• /
• 2016

Automotive today has been transforming to an electronic product by adopting a lot of convenience and safety features, suggesting that joining materials and their mechanical reliabilities are getting more important. In this study, a Sn-Cu-Cr-Ca solder composition having a high melting temperature ($>230^{\circ}C$) was fabricated and its joint properties and reliability was investigated with an aim to evaluate the suitability as a joining material for electronics of engine room. Furthermore, mechanical properties change under complex environment were compared with several existing solder compositions. As a result of contact angle measurement, favorable spreadability of 84% was shown and the average shear strength manufactured with corresponding composition solder paste was $1.9kg/mm^2$. Also, thermo-mechanical reliability by thermal shock and vibration test was compared with that of the representative high temperature solder materials such as Sn-3.5Ag, Sn-0.7Cu, and Sn-5.0Sb. In order to fabricate the test module, solder balls were made in joints with ENIG-finished BGA and then the BGA chip was reflowed on the OPS-finished PCB pattern. During the environmental tests, resistance change was continuously monitored and the joint strength was examined after tests. Sn-3.5Ag alloy exhibited the biggest degradation rate in resistance and shear stress and Sn-0.7Cu resulted in a relatively stable reliability against thermo-mechanical stress coming from thermal shock and vibration.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.13 no.5
• /
• pp.11-20
• /
• 2014

Due to the importance of vehicle detector which plays an essential role in generating real-life traffic information, maintaining detector data quality is preeminent in advanced traffic management and information systems (ATMIS). To this end, agencies periodically conduct performance tests on detectors. Detector evaluation is generally performed by comparing baseline data with corresponding detector data. Here, two important things need to be addressed; one is errors (or uncertainties) included in baseline data and the other is the confidence interval concept to represent evaluation results of sample data to corresponding ones of population. To resolve these problems, a new detector evaluation scheme is introduced and the scheme is applied to individual level detector evaluations of loop, video image, and radar detectors. The purpose of individual level evaluation is to eliminate the balancing (or cancelling-out) effects of over- and under-counts. As a consequence, the proposed scheme is proven to be effectively applied to real-world detector evaluations.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.1
• /
• pp.148-158
• /
• 2011

As critical infrastructure, bridges play an indispensable role in facilitating the distribution of goods. When bridges reach their end of useful life or get damaged by natural disasters such as earthquakes or storms, they have to be removed and reconstructed. When bridges in service need to be reconstructed, user costs occur from vehicle detours and traffic congestions, and social costs occur from noise and dust during construction periods. However, these user and social costs are not considered during reconstruction and the evaluation methods of those costs are vague. Thus, there is lack of appropriate bridge types that consider these costs. Therefore, this paper identifies the social overhead costs that occur during bridge reconstruction, which is also called, users' socioeconomic values. Next, it proposes a method to evaluate user costs during bridge reconstruction, and appraises the method. User costs are evaluated based on traffic information, social and material volumes including the bridge's daily traffic volume, peak hours, detour distance and time. In addition, time delay costs due to traffic operational costs and bridge reconstruction are also taken into consideration.

• Journal of the Microelectronics and Packaging Society
• /
• v.24 no.1
• /
• pp.17-25
• /
• 2017

Recently, research and application for a power module have been actively studied according to the increasing demand for the production of vehicles, smartphones and semiconductor devices. The power modules based on the transient liquid phase (TLP) technology for bonding of power semiconductor devices have been introduced in this paper. The TLP bonding has been widely used in semiconductor packaging industry due to inhibiting conventional Pb-base solder by the regulation of end of life vehicle (ELV) and restriction of hazardous substances (RoHS). In TLP bonding, the melting temperature of a joint layer becomes higher than bonding temperature and it is cost-effective technology than conventional Ag sintering process. In this paper, a variety of TLP bonding technologies and their characteristics for bonding of power module have been described.

• Journal of Welding and Joining
• /
• v.32 no.3
• /
• pp.74-80
• /
• 2014

Due to environmental regulations (RoHS, WEEE and ELV) of the European Union, electronics and automotive electronics have to eliminate toxic substance from their devices and system. Especially, reliability issue of lead-free solder joint is increasing in car electronics due to ELV (End-of-Life Vehicle) banning from 2016. We have prepared engine control unit (ECU) modules soldered with Sn-40Pb and Sn-3.0Ag-0.5Cu (SAC305) solders, respectively. Degradation characteristics of solder joint strength were compared with various conditions of automobile environment such as cabin and engine room. Thermal cycle test (TC, $-40^{\circ}C$ ~ ($85^{\circ}C$ and $125^{\circ}C$), 1500 cycles) were conducted with automotive company standard. To compare shear strength degradation rate with eutectic and Pb-free solder alloy, we measured shear strength of chip components and its size from cabin and engine ECU modules. Based on the TC test results, finally, we have known the difference of degradation level with solder alloys and use environmental conditions. Solder joints degradation rate of engine room ECU is superior to cabin ECU due to large CTE (coefficient of thermal expansion) mismatch in field condition. Degradation rate of engine room ECU is 50~60% larger than cabin room electronics.

• Journal of Trauma and Injury
• /
• v.29 no.1
• /
• pp.1-7
• /
• 2016

Purpose: Tracheobronchial injuries caused by trauma are rare, but can be life threatening. The objective of this study was to evaluate the surgical outcome for patients with tracheobronchial injuries and to determine the difference, if any, between the outcomes for patients with penetrating trauma and those for patients with blunt trauma. Methods: From January 2010 to June 2015, 40 patients underwent tracheobronchial repair surgery due to trauma. We excluded 14 patients with iatrogenic injuries, and divided the remaining 26 into two groups. Results: In the blunt trauma group, injury mechanisms were motor vehicle accident (9 cases), free falls (3 cases), flat falls (1 case) and mechanical injury (1 case). In the penetrating trauma group, injury mechanisms were stab wounds (10 cases), a gunshot wound (1 case) and a stab wound caused by metal pieces (1 case). The mean RTS (Revised Trauma Score) was $6.89{\pm}1.59$ (range: 2.40-7.84) and the mean ISS (Injury Severity Score) was $24.36{\pm}7.16$ (range: 11-34) in the blunt group; the mean RTS was $7.56{\pm}0.41$ (range: 7.11-7.84), and the mean ISS was $13{\pm}5.26$ (range: 9-25) in the penetrating trauma group. In the blunt trauma group, 9 primary repairs, 1 resection with end-end anastomosis, 2 lobectomies, 1 sleeve bronchial resection and 1 pneumonectomy were performed. In the penetrating trauma group, 10 primary repairs and 2 resections with end-end anastomosis were performed. Complications associated with surgery were found in one patient in the blunt trauma group, and one patient in the penetrating trauma group. No mortalities occurred in either groups. Conclusion: Surgical management of a traumatic tracheobronchial injury is a safe procedure for both patients with a penetrating trauma and those with a blunt trauma.