• Journal of the Korean Society of Safety
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• v.35 no.6
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• pp.61-77
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• 2020

In order to establish a conceptual basis and future research direction of safety leadership, this study reviewed domestic and foreign research trends related to safety leadership through systematic literature review methods. The literature search was conducted by combining terms related to safety leadership without limiting the period databases. A total of 195 documents were found, of which the final 59 were used for analysis. As a results, the safety leadership study was the most frequent in relations among variables. The most leadership types were based on transactional leadership and transformational leadership. In addition, studies have been conducted to categorize safety leadership as an independent concept. Safety leadership was mainly studied in the fields of safety engineering, disaster prevention, and business administration. Quantitative studies were mainly conducted to research methods. Based on the results, the research trend related to safety leadership was discussed, and suggestions for future research direction was presented.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.916-917
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• 2001

We investigated the properties of a hybrid type superconducting fault current limiter (SFCL), which consists of a transformer with multiple secondary windings and resistive $YBa_2Cu_3O_7$ (YBCO) thin film stripes. The secondary windings of the transformer were coupled with each other, and a superconducting current limiting unit of YBCO stripes was connected to each of them as a switch. Simple connection in series of SFCL units tends to produce imbalance in power among the units due to slight differences in quench current. In current design, magnetic coupling between the SFCL units provides a solution to power dissipation imbalance, inducing simultaneous quench by current redistribution in the YBCO films.

• Ocean and Polar Research
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• v.34 no.1
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• pp.29-35
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• 2012

We investigated the interannual relationship between chlorophyll concentrations in the western North Pacific and tropical cyclones (TCs) in the western North Pacific by analyzing data collected for >12 years. Despite the short-term scale (2~3 weeks) in the contribution of tropical cyclones to phytoplankton, the current study revealed that the long-term chlorophyll variability in the western North Pacific is profoundly related to long-term variability in the frequency of TCs. It was also found that the Pacific decadal oscillation (PDO) tends to control such relationships between the 2 bio-physical systems. This result suggests a significant climatic relationship between TC activity and marine phytoplankton, and also suggests the possibility of more accurate estimations of primary production in the western North Pacific.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.279-281
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• 2005

In DC traction substation with 12-pulse diode rectifiers, the DC line voltage tends to rise above noload voltage because it can't absorb the regenerative power caused by electric brakes of train. To solve this problem, an IGBT regenerative inverter should be installed and thus recycles the surplus regenerative power by delivering it to the supply grid. In this paper, the DC traction substation equipped with a IGBT regenerative inverter is studied using computer simulation. Matlab/simulink is used to simulate the operation of regenerative inverter which injects the regenerative power into the supply grid and stabilizes the DC line voltage. It is confirmed that the high quality regenerative power is delivered to the supply grid thorough computer simulation.

• Science of Emotion and Sensibility
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• v.11 no.4
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• pp.531-540
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• 2008

This study, based on the college life style and the courage to make that the purpose of the design process of finding out the correlation. Chinese students study the life style can be categorized into 4 kinds. The courage to top a crowded bottom with a broad form of courage prefer to be brought down, getting smaller and smaller. Regular and relevant inclination stores are independent of trust. 2 as a whole are crowded with smooth curves and the courage to the asymmetric shape is preferred. Active investment, emphasis on foreign languages, tends to prefer shopping on the Internet were related.3 outstanding courage, just a little crowded in the cylindrical form is preferred. Trust the big stores, stores see the taste, his taste for products that are relevant to the tendency of pursuing said. 4, a lot of the colony gradient technique Protruding prefer to be in the form of courage. Home will, that tends to emphasize the brand and design were related. Home will, that tends to emphasize the brand and design were related. To recap the contents of the consumer lifestyle, based on the characteristics of their favorite cosmetics containers vary designs. Different forms, depending on their courage to feel emotions that can see the image. Therefore, the design in courage cosmetics on the characteristics of these granular for consumer research, the granular form of product research and the relationship between the elements in their care are made. The marketing strategy is in the consumer market, but needs more fine-grained analysis methods that can tell people.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.651-657
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• 2004

The effects of polymer-cement ratio, antifoamer content and shrinkage-reducing agent content on the air content, setting time, drying shrinkage and strength of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As a result, the air content of the polymer-modified mortars using redispersible polymer powder tends to decrease nth increasing polymer-cement ratio and antifoamer content. Regardless of the antifoamer content, the setting time of the polymer-modified mortars using redispersible polymer powder tends to delayed with increasing polymer-cement ratio. Irrespective of the antifoamer content, the drying shrinkage of the polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and shrinkage-reducing agent content. Regardless of the antifoamer content, the flexural and tensile strengths of the polymer-modified mortars using redispersible polymer powder tends to increase with increasing polymer-cement ratio, and tend to decrease with increasing shrinkage-reducing agent content. However, the compressive strength of the polymer-modified mortars using redispersible polymer powder decreases with increasing polymer-cement ratio and shrinkage-reducing agent content.

• Atmosphere
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• v.21 no.4
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• pp.471-480
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• 2011

This study investigates the characteristics of surface wind in North Korea using mesoscale model WRF. Hourly wind fields were simulated for one year representing mean characteristics of an 11-years period from 1998 to 2008. The simulations were performed on a nested grid from 27 km to 1 km horizontal resolution. The simulated wind map at 10 m above ground level is verified with 27 surface observations. Statistical verification skill score indicates that wind speed tends to overestimate in surface layer. The average RMSE value of the simulated wind speed is around $2.8ms^{-1}$. Wind map in North Korea showed that strong wind speed is distributed in the mountainous and western coastal region. The results of this wind mapping study contribute for the founding of wind energy potential location.

• Current Optics and Photonics
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• v.7 no.1
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• pp.33-37
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• 2023

Real-time adaptive control of laser output polarization is presented in a 10-W-level non-polarization-maintaining (non-PM) fiber amplifier. While the output polarization from a non-PM fiber amplifier tends to be irregular, depending on output power, time, and perturbation, closed-loop polarization control can maintain the polarization extinction ratio at higher than 20 dB. Real-time polarization control can attain the target linear polarization mostly within 1.4-25 ms and shows stability against external perturbations. This approach can satisfy both linear polarization and high output power in a non-PM amplifier, and facilitates optimization of laser performance and maintenance-free operation.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.44-54
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• 1994

Effects of cooling rate, cold reduction %, continuous annealing treatments on the recrystallization texture structure of the A1 killed extra low carbon steel sheet contaning Ti, Nb, and B were investigated. The texture coefficient ratio TC (222)/TC (200) tends to increase with decreasing the cooling rate of the coling process and increasing cold reduction %. However, the texture coefficient ratio tends to decrease as the cold reduction % increases from 80% to 90%, which may be due to the change of the primary texture structure from {554} (225) to {ill] (1 1%). The optimum fabrication procedures for the steel sheet with a maximum texture coefficient ratio may be : furnance cooling after the coiling treatment, 80% cold reduction and the continuous annealing treatment of holding at 80O0C for 1 min., water quenching and then holding at $450^{\circ}C$ for 5min.

• Korean Journal of Materials Research
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• v.28 no.6
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• pp.317-323
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• 2018

Crystal structure of the $L1_2$ type $(Al,X)_3Ti$ alloy (X = Cr,Cu) is analyzed by X-ray diffractometry and the nonuniform strain behavior at high temperature is investigated. The lattice constants for the $L1_2$ type $(Al,X)_3Ti$ alloys decrease in the order of the atomic number of the substituted atom X, and the hardness tends to increase. In a compressive test at around 473K for $Al_{67.5}Ti_{25}Cr_{7.5}$, $Al_{65}Ti_{25}Cr_{10}$ and $Al_{62.5}Ti_{25}Cu_{12.5}$ alloys, it is found that the stress-strain curves showed serration, and deformation rate dependence appeared. It is assumed that the generation of serration is due to dynamic strain aging caused by the diffusion of solute atoms. As a result, activation energy of 60-95 kJ/mol is obtained. This process does not require direct involvement. In order to investigate the generation of serrations in detail, compression tests are carried out under various conditions. As a result, in the strain rate range of this experiment, serration is found to occur after 470K at a certain critical strain. The critical strain increases as the strain rate increases at constant temperature, and the critical strain tends to decrease as temperature rises under constant strain rate. This tendency is common to all alloys produced. In the case of this alloy system, the serration at around 473K corresponds to the case in which the dislocation velocity is faster than the diffusion rate of interstitial solute atoms at low temperature.