• Advances in nano research
• /
• v.13 no.2
• /
• pp.187-197
• /
• 2022

The synthesis of organic and hybrid organic-inorganic perovskites directly from solution improves the cost- and energy-efficiency of processing. To date, numerous research efforts have been devoted to investigating the influence of the various solvent parameters for the synthesis of lead halide perovskites, focused on the effects of different single solvents on the efficiency of the resulting perovskites. In this work, we investigated the effect of solvent blends for the first time on the structure and phase of perovskites produced via the Lewis base vapor diffusion method to develop a new synthetic approach for water-stable CsPbBr₃ particles with nanometer-sized dimensions. Solvent blends prepared with DMF and water-miscible solvents with different Gutmann's donor numbers (D_N) affect the Pb ions differently, resulting in a variety of lead bromide species with various colors. The use of a DMF/isopropanol solvent mixture was found to induce the formation of the Ruddlesden-Popper perovskite based on lead bromide. This perovskite undergoes a blue color shift in the solvated state owing to the separation of nanoplatelets. In contrast, the replacement of isopropanol with DMSO, which has a high DN, induces the formation of spherical CsPbBr₃ perovskite nanoparticles that exhibit green emission. Finally, the integration of acetone in the solvent system leads to the formation of lead bromide complexes with a yellow-orange color and the perovskite CsPbBr₃.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2008.04a
• /
• pp.374-379
• /
• 2008

The purpose of seismic isolation system among them is to lengthen the period of structure and make its period shift from the dominant period of earthquake. In this study, the seismic behavior of arch structure with lead rubber bearing(LRB) and friction pendulum system(FPS) is analyzed. The arch structure is the simplest structure and has the basic dynamic characteristics among large spatial structures. Also, Large spatial structures have large vertical response by horizontal seismic vibration, unlike seismic behavior of normal rahmen structures. When horizontal seismic load is applied to the large spatial structure with isolation systems, the horizontal acceleration response of the large spatial structure is reduced and the vertical seismic response is remarkably reduced.

• The Journal of the Korea Contents Association
• /
• v.17 no.3
• /
• pp.261-273
• /
• 2017

The purpose of study is to measure nurses' empathy levels and to examine the effects of their empathy levels on their life and job satisfaction. The questionnaire was administrated to 150 nurses working in hospitals in Busan. The questionnaire consists of three factors : empathy level, life satisfaction, and job satisfaction. Nurses are classed into two : shift work nurse and non-shift work nurse by their work type. 144 out of 150 questionnaires were used for the analysis with IBM SPSS Statistics 21. The shift work nurses with higher empathy levels showed higher job satisfaction. The non-shift work nurses with higher empathy level revealed higher life satisfaction. Interestingly, while empathy level had positive effects on shift work nurses' job satisfaction(${\beta}=.282$, p=.006), it also had impact on non-shift work nurses' life satisfaction positively(${\beta}=.252$, p=.048). As results show, nurses' life and job satisfaction were positively related to their empathy levels. Given the fact that lack of nurses' empathy often lead to conflicts with patients, in order to improve nurses' job performance, we need a new perspective of understanding the important role of empathy in nurses' job satisfaction and life satisfaction.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.803-805
• /
• 2006

In the paper we have proposed a fabrication method for color reflective cholesteric LCD by an in-plane switching. By applying an in plane electric field, the cholesteric helix could be partially unwound, which lead to shift of selective reflection and exhibition of color change.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.50.1-50.1
• /
• 2011

Lead-free ceramics with a composition of 0.55 mol%$K_4CuNb_8O_23-(K_{1-x}Na_x)NbO_3$ (KCN-KNNx) where $0.45{\leq}x{\leq}0.60$ were synthesized by conventional ceramic processing. Results revealed that the addition of Na was effective in changing the microstructure and relative density of KCN-KNNx. Further, the addition of Na resulted in a slight shift of the phase transition temperatures (To-t and Tc) toward low values. A high mechanical quality factor (Qm) of 1850 was found atx=0.54, which might be due to the build-up of an internal bias field (Ei) within KCN. Thermal hysteresis in KNNx was confirmed with an increase in the Na content during the heating and cooling cycles, resulting from structural changes. Thus, KCN-KNNx with x=0.54 exhibits excellent piezoelectric properties with d33 (97 pC/N), kp (36%), and Qm (1850), being promising candidates for application in high-power piezoelectric devices.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.6
• /
• pp.698-704
• /
• 1999

There are several types of defects of SMDs mounted on PCB, that is, missing components, misalignment, wrong parts and poor solder joints. This research study mainly focuses on measuring of deviation of SMD leads using the partial image of component, not using the full image. This processing based on the partial image has the advantage of the reduction in calculation time compared to the full image. Since position of lead is calculated with respect of the reduction in calculation time compared to the full image. Since position of lead is calculated with respect to pad, the accuracy of the system is not dependent on percise positioning stage. The grabbed image of gray scale is converted into binary format using a cutomatic threshold. After small fragments in the image is removed by a series of morphology operations such as opening and closing, the centroids of PCB pads and SMD leads is obtained together with labeling of blobs. Translational shift and rotationial angle of SMD are succedingly estimated using above information and chip data. The expression that can calculate the maximum deviation of leads with respect to PCB pads has been derived, and inferior mounting of SMD is judged by a given criterion. Some experiments have been executed to verify this measuring scheme.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.11 no.2
• /
• pp.31-40
• /
• 2007

What is the "new paradigm"? It is impossible express it in one or two words, but if one had to; the closest might be the "holistic approach". The expression can be justified by the fact that the conclusions above lead to a greater intermixing of mathematics with engineering and natural sciences subjects, typically expressed in the form of examples of simplified real problems. They also lead to a greater intermixing of subjects within mathematics so that the courses should have less separation e.g. between symbolic and numerical mathematics. The conclusions also lead to the spreading the mathematics courses throughout all study years, not just the first two years. Of course, this should be done with great care in order to guarantee studies that are logically linked together. The new paradigm also means that the needs arising from industrial mathematics must be taken into account in the contents of engineering mathematics courses. Such topics are e.g. multivariate methods, statistics and use of mathematical software. What are we expected to gain from the paradigm shift? The primary benefit should be in obtaining more productive engineers equipped with a better degree of mathematical preparedness for engineering problems. But in addition, it should also promote more intensive use of applied mathematics and easier communication with professional mathematicians, often needed in complicated industrial problems.?Finally, it can be noted that the new paradigm is in harmony with the basic ideas of the CDIO (Conceive - Design - Implement - Operate) initiative for producing the next generation of engineers [1]. New ideas for engineering education can be found also in the homepage of SEFI (European Society for Engineering Education) [2].

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.44 no.2
• /
• pp.140-152
• /
• 2021

During the shift from gasoline vehicles to electric ones, auto parts manufacturing companies have realized the importance of improvement in the manufacturing process that does not require any layout changes nor extra investments, while maintaining their current production rate. Due to these reasons, for the auto part manufacturing company, I-company, this study has developed the simulation model of the PUSH system to conduct a process analysis in terms of production rate, WIP level, and logistics work's utilization rate. In addition, this study compares the PUSH system with other three manufacturing systems -KANBAN, DBR, and CONWIP- to compare the performance of these production systems, while satisfying the company's target production rate. With respect to lead-time, the simulation results show that the improvement of 77.90% for the KANBAN system, 40.39% for the CONWIP system, and 69.81% for the DBR system compared to the PUSH system. In addition, with respect to WIP level, the experimental results demonstrate that the improvement of 77.91% for the KANBAN system, 40.41% for the CONWIP system, and 69.82% for the DBR system compared to the PUSH system. Since the KANBAN system has the largest impacts on the reduction of the lead-time and WIP level compared to other production systems, this study recommends the KANBAN system as the proper manufacturing system of the target company. This study also shows that the proper size of moving units is four and the priority allocation of bottleneck process methods improves the target company's WIP and lead-time. Based on the results of this study, the adoption of the KANBAN system will significantly improve the production process of the target company in terms of lead-time and WIP level.

• Annals of Occupational and Environmental Medicine
• /
• v.34
• /
• pp.34.1-34.13
• /
• 2022

Background: This study aimed to investigate the association between lead exposure and serum gamma-glutamyl transpeptidase (γGT) levels as an oxidative stress marker in male steelworkers. Methods: Data were collected during the annual health examination of workers in 2020. A total of 1,654 steelworkers were selected, and the variables for adjustment included the workers' general characteristics, lifestyle, and occupational characteristics. The association between the blood lead level (BLL) and serum γGT level was investigated by multiple linear and logistic regression analyses. The BLL and serum γGT values that were transformed into natural logarithms were used in multiple linear regression analysis, and the tertile of BLL was used in logistic regression analysis. Results: The geometric mean of the participants' BLLs and serum γGT level was 1.36 ㎍/dL and 27.72 IU/L, respectively. Their BLLs differed depending on age, body mass index (BMI), smoking status, drinking status, shift work, and working period, while their serum γGT levels differed depending on age, BMI, smoking status, drinking status, physical activity, and working period. In multiple linear regression analysis, the difference in models 1, 2, and 3 was significant, obtaining 0.326, 0.176, and 0.172 (all: p < 0.001), respectively. In the multiple linear regression analysis stratified according to drinking status, BMI, and age, BLLs were positively associated with serum γGT levels. Regarding the logistic regression analysis, the odds ratio of the third BLL tertile in models 1, 2, and 3 (for having an elevated serum γGT level within the first tertile reference) was 2.74, 1.83, and 1.81, respectively. Conclusions: BLL was positively associated with serum γGT levels in male steelworkers even at low lead concentrations (< 5 ㎍/dL).

• Journal of the Korean Society of Costume
• /
• v.66 no.7
• /
• pp.192-208
• /
• 2016

Due to the paradigm shift in fashion industry, its contribution to social activities and social enterprises' practice of ethical fashion has been on the rise lately. The surveillance and regulations of international community have increased in light of the betterment of working conditions and protection of the rights, and corporate social responsibility has been emphasized through consumers' interest in ethical consumption. In this regard, the fashion social enterprises' responsible and ethical management can both boost the trust in business and value-added. The study aims to propose feasible methods by exploring ways to induce support from central and local governments, which will lead to the activation of future fashion social enterprises and paradigms shift of consumers's perception and value. The sustainability of social enterprises requires management line or policies that consider social, environmental, economic, and political aspects of virtuous cycle, differentiated internally or externally. Fashion social enterprises also need ethic management and social responsibility management that are distinctive from general fashion enterprises. Thus, they will not be sustainable or differentiated unless entrepreneurial faith and role is not clear. Education and continuous promotion including upcycling are critical to build consumer base as they can make consumers spend ethically and recognize social enterprises. In addition, social education and public relations need to take place in order to internalize consumer pattern. The goal of sustainable corporate social activity is to change the awareness and become social investment that returns some profits to the society as members in line with reviewing corporate image. This can lead to establishing the foundation of securing a big comsumer market and winning the trust of the consumer's through corporate social responsibility and investment.