• Korean Journal of Metals and Materials
• /
• v.49 no.12
• /
• pp.995-1000
• /
• 2011

The microstructure of Cu-24 wt.%Ag filamentary nanocomposite fabricated by a thermo-mechanical process has been investigated by transmission electron microscopy (TEM) observations. This study is focused on the stability of Ag filaments formed by cold drawing; the effects of thermal treatment on the precipitation behavior and distribution of Ag-rich precipitates were also investigated. The Ag filaments elongated along the <111> orientation were observed in Cu-rich ${\alpha}$ phase of the as-drawn specimen and the copper matrix and the silver filament have a cube on cube orientation relationship. Annealing at temperatures lower than $200^{\circ}C$ for the as-drawn specimen caused insignificant change of the fibrous morphology but squiggly interfaces or local breaking of the elongated Ag filaments were easily observed with annealing at $300^{\circ}C$. When samples were annealed at $400^{\circ}C$, discontinuous precipitation was observed in supersaturated Cu solid solution. Ag precipitates with a thickness of 7-20 nm were observed along the <112> direction and the orientation relationship between the copper matrix and the Ag precipitates maintained the same orientation relationship in the as-drawn specimen. The interface between the copper matrix and the Ag precipitates is parallel to {111} and micro-twins were observed in the Ag precipitates.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.20 no.5
• /
• pp.59-67
• /
• 2010

In the paper, we proposed an IM-ACM(Insider Misuse-Access Control Model) for preventing illegal information leakage by insider who exploits his legal rights in the ubiquitous computing environment. The IM-ACM can monitor whether insider uses data rightly using misuse monitor add to CA-TRBAC(Context Aware-Task Role Based Access Control) which permits access authorization according to user role, context role, task and entity's security attributes. It is difficult to prevent information leakage by insider because of access to legal rights, a wealth of knowledge about the system. The IM-ACM can prevent the information flow between objects which have the different security levels using context role and security attributes and prevent an insider misuse by misuse monitor which comparing an insider actual processing behavior to an insider possible work process pattern drawing on the current defined profile of insider's process.

• Structural Engineering and Mechanics
• /
• v.77 no.2
• /
• pp.179-196
• /
• 2021

Experimental investigations on the seismic behaviors of the PVC-FRP Confined Reinforced Concrete (PFCRC) columns under low cyclic loading are carried out and two variable parameters including CFRP strips spacing and axial compression ratio are considered. The PFCRC column finally fails by bending and is characterized by the crushing of concrete and yielding of the longitudinal reinforcement, and the column with a high axial compression ratio is also accompanied by the cracking of the PVC tube and the fracture of CFRP strips. The hysteretic curves and skeleton curves of the columns are obtained from the experimental data. With the increase of axial compression ratio, the stiffness degradation rate accelerates and the ductility decreases. With the decrease of CFRP strips spacing, the unloading sections of the skeleton curves become steep and the ductility reduces significantly. On the basis of fiber model method, a numerical analysis approach for predicting the skeleton curves of the PFCRC columns is developed. Additionally, a simplified skeleton curve including the elastic stage, strengthening stage and unloading stage is suggested depending on the geometric drawing method. Moreover, the loading and unloading rules of the PFCRC columns are revealed by analyzing the features of the skeleton curves. The quantitative expressions that are used to predict the unloading stiffness of the specimens in each stage are proposed. Eventually, an analytical model for the PFCRC columns under low cyclic loading is established and it agrees well with test data.

• Journal of the Korea Safety Management & Science
• /
• v.24 no.4
• /
• pp.33-39
• /
• 2022

Safety has once again emerged as a social issue due to the enforcement of the Serious Disasters Punishment Act and the occurrence of major disasters recently. As such, the safety culture related to unsafe human behavior is drawing attention as various discussions about the importance of safety and accident prevention are currently being undertaken. This study aims to determine whether changes in the level of safety culture in companies affect the accident rate. To this end, we targeted three workplaces in the same company in the domestic manufacturing industry, and 2,790 people were surveyed using DNV's Safety Will(ISRS-C version 4.0) for safety culture level diagnosis. The change in safety culture level and accident rate were compared and analyzed after carrying out safety culture level improvement activities for 5 years. As a result, the level of safety culture increased by 5.8 points, an overall improvement of 9.5%, while the total number of accidents decreased by 20%, from 5 to 4, indicating a general decreasing trend in accident occurrence. Results confirmed that the change in the level of safety culture affects the accident rate, and the improvement in the level of safety culture affects a reduction in accidents. Therefore, this study suggests that efforts to improve the level of safety culture within a company can be associated with accident reduction and accident prevention outcomes.

• Knowledge Management Research
• /
• v.23 no.3
• /
• pp.45-64
• /
• 2022

With the increasing use of social media, the occurrence of cyber crimes on social media has also increased. In this paper, we focus on online sexual harassment among various cyber crimes and discuss how social media users use social media to avoid online sexual harassment. Drawing on threat avoidance theory, the factors affecting avoidance motivation were identified. Avoidance motivation was measured based on the affordance of social media, and the influence of the degree of sexualization was tested to examine how environmental factors affect motivation behavior. The results indicated that the more users perceived sexualization on social media, the lower their motivation to avoid sexual harassment. Thus, it is important to create an atmosphere on social media where crime is minimized, and users are able to respond appropriately by continuously managing their accounts on these platforms.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.29 no.3
• /
• pp.17-28
• /
• 2023

Purpose: This study aims to provide basic data for the future construction plans of the Infectious Disease Hospitals by analyzing the area composition and required room ratios in the wards and ICU of currently under-construction infectious disease hospitals. Methods: 3 Methods have been used in this paper. 1) This study conducted a literature review on major considerations and related guidelines for hospitals specializing in infectious diseases using existing data. 2) Based on the objects and activities of the hospital space, zones and areas were set for each department according to infection control. 3) Based on the established zones and areas, basic plan drawings of three hospitals specializing in infectious diseases currently under construction were collected and architectural drawing analysis was performed. Results: 1) Infectious Diseases Hospital must have a spatial organization that can accommodate patient isolation, infection control, efficiency of medical service, and changes. 2) Zones for infection control are divided into negative pressure and non-negative pressure zones based on airborne precaution isolation. It is divided into clean and contaminated zone according to class of cleanliness by Aseptic technique. Areas are classified by objects (patients, healthcare workers, supplies) and activities (access, medical treatment, support), and a system for organizing space is established based on this. 3) By analyzing the area composition of each departmental area, each required room, and each required space in the wards and intensive care units, it provides basic data for the spatial organization for architectural planning of the infectious disease hospital. Implication: It can be used as basic data when planning related facilities by analyzing the characteristics of the space plan of the required room according to the relationship between activities, movement lines, and operation plans based on user behavior.

• Elastomers and Composites
• /
• v.58 no.1
• /
• pp.44-56
• /
• 2023

Additive manufacturing (AM) or three-dimensional (3D) printing of metals has been drawing significant attention due to its reliability, usefulness, and low cost with rapid prototyping. Among the various AM technologies, fused deposition modeling (FDM) or fused filament fabrication is receiving much interest because of its simple manufacturing processing, low material waste, and cost-effective equipment. FDM technology uses metal-filled polymer filaments for 3D printing, followed by debinding and sintering to fabricate complex metal parts. An efficient binder is essential for producing polymer filaments and the thermal post-processing of printed objects. This study involved an in-depth investigation of and a fabrication route for a novel multi-component binder system with steel alloy powder (45 vol.%) ranging from filament fabrication and 3D printing to debinding and sintering. The binder system consisted of polyvinyl pyrrolidone (PVP) as a binder and thermoplastic polyurethane (TPU) and polylactic acid (PLA) as a carrier. The PVP binder held the metal components tightly by maintaining their stoichiometry, and the TPU and PLA in the ratio of 9:1 provided flexibility, stiffness, and strength to the filament for 3D printing. The efficacy of the binder system was examined by fabricating 3D-printed cubic structures. The results revealed that the thermal debinding and sintering processes effectively removed the binder/carrier from the cubic structures, resulting in isotropic shrinkage of approximately 15.8% in all directions. The scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) patterns displayed the microstructure behavior, phase transition, and elemental composition of the 3D cubic structure.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6D
• /
• pp.767-774
• /
• 2008

This study has been developed the way that evaluates the road safety using the speed of individual vehicles at curve sections in 2-lane rural highways. For this study, we developed variation of operational speed for the individual vehicle using the speed of vehicles in 96points of selected roads. Drawing out of variation of operational speed for the individual vehicle, estimation models for speed variation of individual vehicles considering horizontal alignments and vertical alignments of the roads have been developed. These models presents the way to evaluate road safety out of the operational speed and acceleration of individual vehicles. Considering safety and based on the results of these study above, some regular spots are ranked by "good", "fair", "bad". The results that this study showed in this paper could be useful to derive some particular spots that needs to be improve in terms of safety.

• Journal of Practical Engineering Education
• /
• v.15 no.2
• /
• pp.389-400
• /
• 2023

Technological advancements in the field of information and communication have led to the advent and usage of various types of smart devices, which have significantly altered people's usage behaviors and environments. This change has also been applied to the learning environment, where various smart devices are appearing and the learning behavior of learners is changing accordingly. In this study, we investigate learners' perceptions of digital note-taking behaviors focusing on the recently emerged learning media, tablet PCs and digital pens. Drawing upon the expectancy-confirmation model, we conduct a study on the factors affecting the (dis)confirmation and (dis)satisfaction of undergraduate students with tablet PCs and digital pens by comparing their expectations with their actual use experiences. An open-ended survey was conducted among students at C University in Korea, and the responses were analyzed through qualitative content analysis to derive four factors of expectation-confirmation and satisfaction and three factors of expectation-disconfirmation and dissatisfaction. Based on these findings, we provide academic and educational implications.

• Science of Emotion and Sensibility
• /
• v.11 no.4
• /
• pp.461-480
• /
• 2008

There are innumerable studies on technology adoption and usage continuance; most examine cognitive factors while affective factors or the feelings of users are left relatively unexplored. Although attitude and user satisfaction are factors commonly considered in Information Systems(IS) research, they represent only some aspects of feelings. In contrast, researchers in diverse fields have begun to note the importance of feelings in understanding and predicting human behavior. Feelings are anticipated to be essential particularly in the context of modern applications, such as mobile internet(M-internet) services, where users are not simply technology users but also service consumers. Drawing on the support of consumer research, social psychology and computer science, this study proposes a balanced cognition-affect model of IS continuance. Prior works in relation to IS research have already considered the emotional factors. The common factors are enjoyment, anxiety, affect and satisfaction. The main difference in our study is that the factors that we used are the primary dimensions of affect according to Circumplex Model of Affect. The horizontal axis of the model represents the pleasure dimension and the vertical represents the arousal dimension. Other emotional factors such as enjoyment and anxiety can be viewed as a combination of these two dimensions, and they can be placed in the vector space formed by these two primary dimensions. Affect has been defined as the enjoyment a person derives from using computers. Satisfaction has different conceptualizations. It has been conceptualized as judgment based on the expectation disconfirmation theory. Thus, while prior works considered the direct and indirect effects of "feeling-related constructs"(enjoyment and anxiety) on usage behavior, our study proposes effects of "feeling-based constructs"(pleasure and arousal). The balanced cognition-affect model is tested in a survey of, M-internet service users. The results establish the validity of the model.