• The Journal of Engineering Research
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• v.1 no.1
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• pp.5-14
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• 1997

The purpose of thesis is to analyze the radiation characteristics of an offset gregorian antenna in order to design the satellite-loaded antenna. In order to compute the radiation pattern of the sub-reflector, the reflected wave is obtained by GO(Geometric Optics) at an arbitrary shaped sub-reflector. Then the total radiation EM wave is obtained by summing the diffracted fields obtained by UTD(Uniform Geometrical Theory of Diffraction) and the GO fields. In order to calculate the far field radiation pattern of the main reflector, the radiation integral equation is derived from the induced current density on reflector surface using PO(Physical Optics). The kernel is expanded in terms of Jacobi-Bessel series for increasing the computational efficiency, then the modified radiation integral is represented as the double integral equation independent of observation points. When the incident fields are assumed to be x-or y-polarized field, the characteristics of radiation patterns in the gregorian antenna is analyzed in case of the main reflector having the focal length of 62.4$\lambda$, diameter of 100$\lambda$, and offset height of 75$\lambda$, and the sub-reflector having the eccentricity of 0.501, the inter focal length og 32.8$\lambda$, the horn axis angle of $9^{\circ}$ and the half aperture angle of $15.89^{\circ}$. The cross-polarized level and side lobe level in the offset geogorian reflector are reduced by 30dB and 10dB, respectively, in comparison with those of the offset parabolic antenna.

• Journal of Korean Society for Quality Management
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• v.44 no.1
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• pp.61-76
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• 2016

Purpose: In order to use a word as academic terminology, we must first take a look at the meaning of that word as it is commonly used and then consider whether or not the connotation of that word is suitable to be used as academic terminology. Presently, the word Pumjil(品質) is being used as academic terminology occupying an important position in the field of business administration in Korea and is usually translated into English as 'quality'. The same is true in Japan. However, as is the case with many Korean words, the meaning that the word implies has a tendency to change gradually over time. This tendency can account for the changes or additions to the meaning a word connotes. Methods: This dissertation aims to escape from such biased ideas and study the meaning of 'Pum-Jil品質' from the view of humanities and exegetics. Then the natural definition of the word as far as business administration is concerned can be considered. Results: 'Pum-Jil品質' has been used amid changes in modern times(historic texts in both Korea and China. In Korea particularly, the word was used in the royal court until comparatively modern times.), and now it is also widely used in the field of business administration. In this process of change, a notable point is that 'Pum-Jil品質', which was originally used to mean 'nature or character of a man', took on a new meaning, 'a certain quality of a thing or a good'. Conclusion: 'Pum-Jil品質' should require basic functional 'quality' of goods or services as a prerequisite. And the functional quality should meet consumers' needs, as the pledge (trust; 信賴) for quality is between suppliers and consumers. Without consumer's trust for goods, the relationship between suppliers and consumers cannot be maintained. So goods must exchange with trust, not expenses. In conclusion, we believe it is reasonable to understand 'Pum-Jil品質' based on the meaning of 'evidence or similar rating for pledge (trust)' from the view of humanities and exegetics. In conclusion, we believe it is reasonable to understand 'Pum-Jil品質' based on the meaning of 'evidence or similar rating for pledge (trust)' from the view of humanities and exegetics.

• Proceedings of the Korean Society of Laser Processing Conference
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• 1998.11a
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• pp.0-0
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• 1998

-Part I- As market needs become more various, the production of smaller quantities of a wider variety of products becomes increasingly important. In addition, in order to meet demands for more efficient production, long-term unmanned factory operation is prevailing at a remarkable pace. Within this context, laser machines are gaining increasing popularity for use in applications such as cutting and welding metallic and ceramic materials. FANUC supplies four models of $CO_2$ laser oscillators with laser power ranging from 1.5㎾ to 6㎾ on an OEM basis to machine tool builders. However, FANUC has been requested to produce laser oscillators that allow more compact and lower-cost laser machines to be built. To meet such demands, FANUC has developed six models of Slab type YAG laser oscillators with output power ranging from 150W to 2㎾. These oscillators are designed mainly fur cutting and welding sheet metals. The oscillator has an exceptionally superior laser beam quality compared to conventional YAG laser oscillators, thus providing significantly improved machining capability. In addition, the laser beam of the oscillator can be efficiently transmitted through quartz optical fibers, enabling laser machines to be simplified and made more compact. This paper introduces the features of FANUC’s developed Slab type YAG laser oscillators and their applications. - Part II - All-solid-state lasers employing laser diodes (LD) as a source of pumping solid-state laser feature high efficiency, compactness, and high reliability. Thus, they are expected to provide a new generation of processing tools in various fields, especially in automobile and aircraft industries where great hopes are being placed on laser welding technology for steel plates and aluminum materials for which a significant growth in demand is expected. Also, in power plants, it is hoped that reliability and safety will be improved by using the laser welding technology. As in the above, the advent of high-power all-solid-state lasers may not only bring a great technological innovation to existing industry, but also create new industry. This is the background for this project, which has set its sights on the development of high-power, all-solid-state lasers with an average output of over 10㎾, an oscillation efficiency of over 20%, and a laser head volume of below 0.05㎥. FANUC Ltd. is responsible for the research and development of slab type lasers, and TOSHIBA Corp. far rod type lasers. By pumping slab type Nd: YAG crystal and by using quasi-continuous wave (QCW) type LD stacks, FANUC has already obtained an average output power of 1.7㎾, an optical conversion efficiency of 42%, and an electro-optical conversion efficiency of 16%. These conversion efficiencies are the best results the world has ever seen in the field of high-power all-solid-state lasers. TOSHIBA Corp. has also obtained an output power of 1.2㎾, an optical conversion efficiency of 30％, and an electro-optical conversion efficiency of 12%, by pumping the rod type Nd: YAG crystal by continuous wave (CW) type LD stacks. The laser power achieved by TOSHIBA Corp. is also a new world record in the field of rod type all-solid-state lasers. This report provides details of the above results and some information on future development plans.

• Journal of the Korean Geotechnical Society
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• v.37 no.2
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• pp.19-31
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• 2021

Micropiles are cast-in-place piles with small diameters. The advantage of micropile is low construction expense and simple procedures, so it is widely applied to existing buildings and structures for the reinforcement of foundation and seismic performances. The base expansion structure has been developed following the original mechanism of horizontal expansion steps under compressive loading. This kind of structure can be installed at the pile end to improve the bearing capacity by tip area enlargement and horizontal force increment to the pile surface area. However, 'Micropile with base expansion structure' cannot be put into practical use, because detailed verification for the developed technique has not been conducted so far. In this research, 3-D numerical analysis was conducted to figure out the bearing mechanism of base expansion micropile and to verify the bearing capacity improvement compared to the general micropiles. 3-D modelling of micropile with base expansion structure was carried out and input parameter was determined. Bearing mechanism induced by base expansion structure was analyzed by lab-scale modelling, and bearing capacity improvement was verified by field-scale analysis.

• Journal of Convergence for Information Technology
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• v.11 no.6
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• pp.131-138
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• 2021

The purpose of this study is to derive the implications of Grit research by analyzing domestic research trends on Grit, which is a non-cognitive subject that has been actively researched in Korea recently in order to grasp the achievements so far and to seek directions for research. The analysis method was analyzed according to the pre-set criteria (annual publication status, research subject, research method, research topic, etc.) which were focusing on KCI listed and KCI excellent Grit papers among domestic academic papers of 'RISS'. As a result of the study, from 2013 to 2019, a total of 203 papers were searched and published in 92 domestic journals. Beside that, the subjects of the study, 88 cases (43.35%) were college students and 180 cases (88.67%) were quantitative studies as the research method. So, the most common research method was quantitative research. As a quantitative research method, the structural relationship between Grit and other variables, mediating effect, difference verification, and moderation effect verification were shown in order, and qualitative research has been conducted since 2017 to develop the concept of Grit, the Grit scale, and the corresponding factor structure and validity. This study will contribute to the educational field by presenting the implications of research on the development of Grit in Korea.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.47-52
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• 2021

Recently, the share of wind power in energy markets has sharply increased with the active development of renewable energy internationally. In particular, large-scale wind farms are being developed far from the coast to make use of abundant wind resources and to reduce noise pollution. In addition to the electromagnetic interference (EMI) caused by offshore wind farms to coastal or air surveillance radars, it is necessary to investigate the EMI on global maritime distress and safety system (GMDSS) communications between ship and coastal stations. For this purpose, this study investigates whether the transmitted field of MF/HF band from a ship would be subject to interference or attenuation below the threshold at a coastal receiver. First, using geographic information system digital maps and 3D CAD models of wind turbines, the area of interest is electromagnetically modeled with patch models. Although high frequency analysis methods like Physical Optics are appropriate to analyze wide areas compared to its wavelength, the high frequency analysis method is first verified with an accurate low frequency analysis method by simplifying the surrounding area and turbines. As a result, the received wave power is almost the same regardless of whether the wind farms are located between ships and coastal stations. From this result, although wind turbines are large structures, the size is only a few wavelengths, so it does not interfere with the electric field of MF/HF distress communications.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.10-18
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• 2022

Purpose: For smooth performance of flood analysis due to heavy rain disasters at energy storage facilities in the Incheon area, field surveys, observational surveys, and pre-established reports and drawings were analyzed. Through the field survey, the characteristics of pipelines and rivers that have not been identified so far were investigated, and based on this, the input data of the SWMM model selected for inundation analysis was constructed. Method: In order to determine the critical duration through the probability flood analysis according to the calculation of the probability rainfall intensity by recurrence period and duration, it is necessary to calculate the probability rainfall intensity for an arbitrary duration by frequency, so the research results of the Ministry of Land, Transport and Maritime Affairs were utilized. Result: Based on this, the probability of rainfall by frequency and duration was extracted, the critical duration was determined through flood analysis, and the rainfall amount suggested in the disaster prevention performance target was applied to enable site safety review. Conclusion: The critical duration of the base was found to be a relatively short duration of 30 minutes due to the very gentle slope of the watershed. In general, if the critical duration is less than 30 minutes, even if flooding occurs, the scale of inundation is not large.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.719-725
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• 2022

This study aimed to measure, quantitatively evaluate, and set the criteria for the minimum lead(Pb) shield thickness per level of clinically applied electron beam energy. The lead shield thickness per electron beam energy was measured using the primary field 95% reduction based on the open field at the depth of maximum dose (d_max) and depth from the surface as the reference depth of tissue dose(10 mm). The measured values were 1.906 mmPb and 1.992 mmPb at the d_max and 10 mm, respectively, regarding the lead shield thickness for 6 MeV electron beam; 2.746 mmPb and 3.743 mmPb for 9 MeV electron beam, 3.718 mmPb and 6.093 mmPb for 12 MeV electron beam, 7.300 mmPb and 15.270 mmPb for 16 MeV electron beam, and 16.825 mmPb and 25.090 mmPb for 20 MeV electron beam. Consequently, a thicker lead shield was required if the measurement was at 10 mm. The required lead shield thickness was also higher than that of the theoretical formula for electron beams of ≥ 16 MeV.

• The Journal of Korean Society of Virology
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• v.29 no.2
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• pp.55-64
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• 1999

In Yugoslavia, hemorrhagic fever with renal syndrome (HFRS) is one of the important national health problem, but no vaccine has been used to prevent HFRS. Since first HFRS case in 1952, sporadic cases of HFRS occurred every year and over 4,000 registered cases with $1{\sim}16%$ mortality so far. We performed a prospective, randomized double-blind placebo-controlled trial to evaluate the effectiveness of $Hantavax^{TM}$ against HFRS in 3,900 healthy adults living in the endemic areas of Yugoslavia. 1,900 people were given 0.5 ml of Hantavax subcutaneously twice at one month interval and a booster shot at one year after. For controls other 2,000 healthy people were given 0.5 ml of physiolosical saline as a placebo. We investigated HFRS cases in both the vaccinated and nonvaccinated groups by monitoring the program for patient registration in the areas from 1996 to 1998, and the effect of vaccine was analyzed epidemiologically. No confirmed case of HFRS was observed among 1,900 Hantavax vaccinees, while 20 confirmed cases were observed among 2,000 nonvaccinated control group. There were no remarkable side effects among the vaccinees either locally or in general after inoculation of the vaccine. The Hantavax vaccine showed statistically significant protective efficacy against HFRS among Yugoslavian people.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.15-24
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• 2006

The evaluation of shear modulus is very important in various fields of civil engineering. Non-destructive seismic methods can be used to determine shear wave velocity ($V_s$) profile. Non-destructive seismic methods geneally consist of three steps: field testing, evaluation of dispersion curve, and determination of Vs profile by inversion process. Non-destructive seismic methods can be divided into two categories according to the number of receivers used for data reduction: two-channel tests and multi-channel tests. Two channel tests use apparent velocity dispersion curve and multi-channel tests use mode dispersion curves. Multi-channel tests using mode dispersion curve can reduce calculation time to determine soil profile and uncertainties in inversion process. So far, only multi-channel tests can determine mode dispersion curves but multi-channel test needs many receivers to determine reasonable mode dispersion curves. In this paper, HWAW (Harmonic Wavelet Analysis of Wave) method is applied to determine mode dispersion curves. HWAW method uses short test setup which consists of two receivers with a spacing of 1 to 3 m. Through numerical simulations and field application, it is shown that HWAW can determine resonable mode disperson curves.