• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.8
• /
• pp.1117-1123
• /
• 2011

Ungrounded power systems are adopted onboard vessels which enable more stabilized power supply even in case of electric leakage to hull. If earthing faults happen at these systems, they make grounding impedances of power lines unbalanced each other on the three phases, resulting in high voltages to hull which can bring more possibilities of electric shocks and electric fires. This study focuses on how to configure a calculation module for transferring a grounded condition by lowered insulation resistance into a vector diagram of the voltages to hull. By using the module, the loci of neutral points were acquired to analyze how voltages to hull are affected by earthing faults and the distributed capacitances between power lines and hull. The suggested module was simulated and compared to the measured values from a test power system in good results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.1
• /
• pp.141-149
• /
• 2009

In this paper, quasi-static FDTD method is implemented by FORTRAN programming, and it is used for analysis of body induced current in middle frequencies. The quasi-static FDTD program is validated by comparing the calculation result with analytic solution of the test model, to which it is difficult to apply conventional FDTD. It is confirmed that the time-step is reduced by $5.68{\times}10^6$ times. Using validated numerical technique, body induced current distribution in high resolution 3-D human model is calculated for 20[kHz] magnetic field exposure and 1[MHz] electric field exposure. Also, the effect of grounding condition of both feet on the distribution and amplitude of the induced current is analyzed. It is expected that this research can be applied to various fields including safety assessment of body induced current and development of diagnosis devices using bio-electricity.

• Explosives and Blasting
• /
• v.32 no.3
• /
• pp.18-25
• /
• 2014

Ground vibration and noise from blasting operation are known to be the most representative constituents which can cause human and material damage. In this study, the effect of delay time on ground vibration is investigated by adopting seven different delay times in bench blasting. For each delay time, three blasting operations were performed. The prediction equations for blasting vibration are derived from 50 sets of measurement and the time theory of Langefors is evoked in the analysis of the blasting vibrations and frequencies. For the delay times of 8 ms and 28 ms, the average values of ground vibration are 5.76 cm/sec and 5.75 cm/sec, respectively, which are considerably low. Also the cyclic variation in the vibration measurements with the delay time confirms the interference effect. From the application of the measurements of blasting vibration and frequency to the time theory of Langefors, it is concluded that the optimum delay times are 8 ms and 24 ms for the test site.

• The Journal of the Korea Contents Association
• /
• v.14 no.8
• /
• pp.197-206
• /
• 2014

This research intends to explore services, programs or policies for supporting married immigrant women to qualify themselves for being employed from the professional point of view on the assumption that their desire to get a job is high. To achieve this purpose, a delphi survey was conducted with a panel of 13 experts related to multi cultural family support in three sessions from December 20, 2013 to June 5, 2014. To analyze the collected data, descriptive statistics, including frequency, percentage, the mean, and standard deviation, were implemented, and Kendall's W for the internal reliability test on the survey instrument was carried out for statistical processing. The results are as follows : from the first session, services, programs, and policies in the level of married immigrant women themselves, children, parents in law and/or husband, organizations, and government were suggested. The highest item in average is systematization of levelwise Korean teaching program. The next higher items in average are daycare service during job training, parents in law and/or husband's consideration, parenting support services, program development of the organizations, linkage and integration system among the government ministries. As a result of the Kendall's W performed for the internal reliability test of the Delphi research, it has been concluded that the professionals' view on the supportive measures' important contents was statistically identical. According to the results of the Delphi research, systematization of levelwise Korean teaching program most required for the furtherance of the married immigrant women's entering the workforce, followed by provision of the services to draw family support, a grounding teaching of Korean corporate culture, and reconsideration of the policies.

• Journal of Navigation and Port Research
• /
• v.43 no.6
• /
• pp.369-376
• /
• 2019

Ship hydrodynamics in the confined waterways is challenging. When a ship is maneuvering in confined waterways, the hydrodynamic behavior may vary significantly because of the hydrodynamic interaction between the bottom of the ship hull and the seabed, or so-called shallow water effects. Thus, an accurate prediction of shallow water and bank effects is essential to minimizing the risk of the collision and the grounding of the ships. The hydrodynamic derivatives measured by the virtual captive model test provide a path to predicting the change in ship maneuverability. This paper presents a numerical simulation of captive model tests to predict the maneuverability of a ship in confined waterways. Also, straight and zig-zag simulation were conducted to predict the trajectory of a ship maneuvering in confined waterways. The results showed that the asymmetric flow around a ship induced by vicinity of banks causes pressure differences between the port and starboard sides and the trajectory of a ship maneuvering in confined waterways.

• Archives of design research
• /
• v.19 no.1 s.63
• /
• pp.283-292
• /
• 2006

This study developed 'Design Career Aptitude Scale' to help design majoring college students who are seeking their career goals or conflicting to decide their majors. The subscales of the 'Design Career Aptitude Scale' are 'basic job competency', 'basic design competency' and' advanced design competency'. This study further classified the 'basic job competency' and 'basic design competency' into several subareas and defined each concepts. Based upon the classification of each subareas, tentative test items were developed through the verification of validity three times by seven design professionals. A pilot study of the developed scale was administered to 506 design majoring college students. The results by exploratory factor analysis were that the basic job competency was composed of four factors; ability of interpersonal relations, goal-driven ability, problem solving ability and self-developing ability. The basic design competency was composed of five factor, grounding in design, computer skills, material sensitivity, formative ability and color sensitivity. The results can be seen as an adequate, delicate factor structure to represent design aptitude, and also the scale can be a useful tool to the students who are conflicting to decide their majors and careers. The further study needed to validate the scale through the investigation of the relationship with related scales measuring designing ability, and with other criteria-referenced group.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.21 no.1
• /
• pp.83-95
• /
• 2018

With recent technological advances in the shipbuilding industry, vessels have been improved in size and performance. As a result, an accident such as grounding, caused by a single ship-to-ship collision, could lead to a large-scale maritime disaster. Considering the seriousness of the situation, the international community has been consistently updating the standards for Electronic Navigational Chart(ENC) to improve the maritime safety. S-57, the existing ENC standard governed by the International Hydrographic Organization(IHO), includes standards for generating conventional binary-type ENC data sets. The S-57 standard, however, has not been updated since the release of Version 3.1 in December 2000. Since then, the standard has failed to reflect technological development regarding maritime spacial information, which has been consistently improving. In an effort to address this concern, the IHO designated S-100, i.e., the next-generation ENC production standard. S-100 differs from S-57 in data exchange type. Contrary to the conventional ENC standards, which use binary-type data, S-10X, based on the next-generation ENC standards, uses ENC data composed of Feature Catalogue, Portrayal Catalogue, and GML. Considering this fact, it is necessary to update S-58, the ENC validation check standard, or designate a new standard for ENC validation checks. This study is developed own software to implement validation checks for new types of data, and identified improvement points based on the test results.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.12
• /
• pp.33-42
• /
• 2007

The assessment of shear wave velocity($V_s$) in soft soils is extremely difficult due to the soil disturbances during sampling and field access. After a ring type field $V_s$ probe(FVP) has been developed, it has been applied at the southern coastal area of the Korean peninsular. This study presents the upgraded FVP "blade type FVP", which minimizes soil disturbance during penetration. Design concerns of the blade type FVP include the tip shape, soil disturbance, transducers, protection of the cables, and the electromagnetic coupling between transducers and cables. The cross-talking between cables is removed by grouping and extra grounding of the cables. The shear wave velocity of the FVP is simply calculated by using the travel distance and the first arrival time. The large calibration chamber tests are carried out to investigate the disturbance effect due to the penetration of FVP blade and the validity of the shear waves measured by the FVP. The blade type FVP is tested in soils up to 30m in depth. The shear wave velocity is measured every 10cm. This study suggests that the upgraded blade type FVP may be an effective device for measuring the shear wave velocity with minimized soil disturbance in the field.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.59 no.1
• /
• pp.27-37
• /
• 2014

This study was carried out to characterize the color of noodle sheet made from Korean wheat cultivars, which were then evaluated on grain and flour properties, in order to enhance the breeding-line selection for noodle wheat. In particular, a rapid method was applied to investigate the effects of iron (Fe) contents on the lightness of noodle sheet for the selection of breeding-lines with high Fe contents. Wheat flour lightness of Korean wheat cultivars had a negative correlation with ash (r = -0.634, P<0.01), protein (r = -0.635, P<0.01) and total polyphenols (r = -0.493, P<0.05). The noodle sheet color showed a positive correlation with lightness, but a negative correlation with test weight, 1000 kernels weight, PPO activity and total polyphenol contents. Also, upon the wheat flour properties, the ash, protein and total polyphenol contents had a negative correlation with the lightness of noodle sheet, and this relation varied depending on the year and cultivars. The Fe content had a negative relation with the color of wheat flour and the lightness of noodle sheet, and the potassium hexacyanoferrate(II) trihydrate (PHT) test resulted in blue color. There was no correlation between Fe contents and the color of grains with PHT treatment, but after grounding the whole grains, a negative correlation was found between Fe contents and redness (r = -0.665, P<0.001) and yellowness (r = -0.658, P<0.001) of whole wheat flour with PHT treatment. On the other hand, the lightness of wheat flour with PHT treatment showed a negative relation with Fe content.

• Journal of the Microelectronics and Packaging Society
• /
• v.28 no.3
• /
• pp.1-7
• /
• 2021

In this paper, by embedding a bare-die chip-type drive amplifier into the PCB composed of ABF and FR-4, it implements an embedded active device that can be applied in 28 GHz band modules. The ABF has a dielectric constant of 3.2 and a dielectric loss of 0.016. The FR-4 where the drive amplifier is embedded has a dielectric constant of 3.5 and a dielectric loss of 0.02. The proposed embedded module is processed into two structures, and S-parameter properties are confirmed with measurements. The two process structures are an embedding structure of face-up and an embedding structure of face-down. The fabricated module is measured on a designed test board using Taconic's TLY-5A(dielectric constant : 2.17, dielectric loss : 0.0002). The PCB which embedded into the face-down expected better gain performance due to shorter interconnection-line from the RF pad of the Bear-die chip to the pattern of formed layer. But it is verified that the ground at the bottom of the bear-die chip is grounded Through via, resulting in an oscillation. On the other hand, the face-up structure has a stable gain characteristic of more than 10 dB from 25 GHz to 30 GHz, with a gain of 12.32 dB at the center frequency of 28 GHz. The output characteristics of module embedded into the face-up structure are measured using signal generator and spectrum analyzer. When the input power (P_in) of the signal generator was applied from -10 dBm to 20 dBm, the gain compression point (P_1dB) of the embedded module was 20.38 dB. Ultimately, the bare-die chip used in this paper was verified through measurement that the oscillation is improved according to the grounding methods when embedding in a PCB. Thus, the module embedded into the face-up structure will be able to be properly used for communication modules in millimeter wave bands.