• Journal of Hydrogen and New Energy
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• v.22 no.2
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• pp.152-160
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• 2011

The electromagnetic characteristics of FCEVs (fuel cell electric vehicles) are much different from the existing combustion engine cars as well as hybrid, plug-in-hybrid, and pure electric vehicles due to the high voltage/current generated by a fuel cell stack which uses a compressed hydrogen gas reacted with oxygen. To operate fuel cell stack efficiently, BOP (Balance of Plant) which is consisted of many motors in water pump, air blower, and hydrogen recycling pump as well as inverters for these motors is essential. Furthermore, there are also electric systems for entertainment, information, and vehicle control such as navigation, broadcasting, vehicle dynamic control systems, and so on. Since these systems are connected by high voltage or general cables, EMC (Electromagnetic compatibility) analysis for high voltage and general cable of FCEV is the most important element to prevent the possible electric functional safety errors. In this paper, electromagnetic fields by high voltage and general cables for FCEVs is studied. From numerical analysis results, total time harmonic electromagnetic field strength from high voltage and general cables have difference of 13~16 dB due to ground effect by impedance matching. The EMI results of FECV at 10 m distance shows difference of 41 dB at 30 MHz and 54 dB at 230 MHz compared with only general cable routing.

• Journal of the Korea Fashion and Costume Design Association
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• v.20 no.4
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• pp.163-174
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• 2018

Consumer and property evaluation of wetsuit materials were conducted to obtain useful data for developing competitive products that meet consumer expectations and improving industrial competitiveness. Data were collected through online surveys of 213 domestic consumers who have experienced wearing wetsuit among marine leisure activities. Five types of commercial wet suit materials by brand and four types of commercial wet suit materials with the same quality by thickness were collected. Then, their physical properties, salt water resistance and thermal insulation rate were evaluated and compared. As a result, the most commonly used wetsuit material is 3 to 5 mm thick, and the basic jersey material is bonded on both sides. As a processing for imparting functionality, processing for improving warmth and reducing surface resistance are most frequently used. Consumers often feel uncomfortable when wearing a wetsuit, such as wearing comfort, weight, ease of movement, stretchability, and clothing pressure, which are different from those of casual wear. Also, mechanical strength and warmth were considered to be the most important criteria for selection of wetsuit material for purchase or rental. The mechanical properties of brand A and B were better than those of brand C, D, and E. Resilience and thermal shrinkage were better in brand C, D, and E. On the other hand, there was no significant difference in the physical properties due to the difference in thickness of the material at the same quality. Also, it was found that the thicker the material, the more stable it is in the heat. Brand A and B had superior salt water resistance than brand C, D, and E. In the thermal insulation test, brand A and B showed better insulation characteristics than brand C, D, and E, but the types of bonded fabric and surface finishing of materials were thought to have affected. In comparison of the thickness, the thicker the materials, the better the salt resistance and the thermal insulation.

• Journal of the Korean Magnetics Society
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• v.21 no.2
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• pp.43-47
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• 2011

It is known that the Fe-Al transition metal compounds have a lot of disagreement about structural stability and magnetism. In this study, the correlation between magnetism and atomic structure of ordered $B_2$, $L1_2$, and $D0_3$ structured Fe-Al compounds has been investigated using the all-electron full-potential linearized augmented plane wave (FLAPW) method based on the generalized gradient approximation (GGA). We found that considered all the structures were calculated to be stabilized in a ferromagnetic state. The calculated spin magnetic moments of the Fe atoms for B2 and $L1_2$ structures were 0.771 and 2.373 ${\mu}_B$, respectively, and that of Fe(I) and Fe(II) in $D0_3$ structure calculated to be 2.409 ${\mu}_B$, 1.911 ${\mu}_B$, respectively. In order to investigate structural stability between $L1_2$ and $D0_3$ structures, we performed the formation enthalpy calculations. As a result, the $D0_3$ structure is found to be more favorable than $L1_2 one by energy difference 16 meV/atom, which is well consistent with the experimental observation. We understood about structural stability and magnetism for Fe-Al compounds in terms of analysis of their atomic and electronic structures.

• Journal of the Korean Society of Food Science and Nutrition
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• v.5 no.1
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• pp.39-51
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• 1976

We arrive at the conclusion as follows as for the connection between dietary life, hours of exercise and growth of body, based on the survey of their height, this circumference of the breast and their body weight, and the questionnaires to the pupils of 36,547 in totals (contained the primary and middle school boys and girls) in four districts(named A, B, C and D district) of Jeonlla Bug Do from April, 1970 to March, 1973. (1) The growth in height. The boys from 6 to 7 years old are nearly same in all districts, but as age increases, those of A district grow more rapidly than those of B, C and D districts, while those of B, C and D districts grow almost samely. The girls already from 6 years old on are different between A district and B, C, D district. The average of height in Jeonlla Bug Do is not different from that of Gyungi Do and whole nation in the pupils from 6 to 11 years old, and that of Japan from 6 to 7 of age, while it falls behind them as age increases. (2) The growth in the circumference of the breast. The boys from 6 to 9 years old show nearly the same tendency in all districts, after that age the boys in A district tend to grow rapidly, those in B district most fall behind, and those in C, D districts show the same tendency. Contrasted with height the growth in the circumference of the breast does not show the difference in each district so far as 14 of age, but after 15 years old it shows a little difference by falling behind of pupils in A district, while those B, C, D districts show almost the same tendency. The average of the circumference of the breast in Jeonlla Bug Do of the pupils from 10 to 11 of age is almost same to that of Gyungi Do, whole nation and Japan, but shows difference after that age. (3) The growth of body weight. The body weight of boys over-all the investigated whole age shows the superiority in A district and a little lowness in D district which is almost same to that of B, C districts. In that of girls, A district is superior in from 6 to 9 of age, and all districts are nearly same after that age. The average in Jeonlla Bug Do is one and the same to those of Gyungi Do, whole nation and Japan as in the height, but shows the great difference as years grow. (4) The dietary life of the pupils in Jeonlla Bug Do depends chiefly upon a carbohydrate and is very low in the intake of fat and protein. Connected with a view point of districts, the intake of protein is a little more in A district than in the other districts, and is nearly same in the other districts. They tend more to eat mixed food, but about 40% of them do not yet eat it. The contents and taking of lunch is bad in the highest degree, to which their parents are entirely indifferent. As far as the hours of exercise are concerned with, about 40% of all pupils must go to the school from very far, which gives them the heavy physical suffering, and especially it is remarked that the middle school boys and girls should attend school from farther than the primary school boys and girls.

• Korean Journal of Environment and Ecology
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• v.23 no.3
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• pp.272-279
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• 2009

The purpose of this study is to examine noise attenuation according to hedge species and thickness of their leaves. The order of their decrease effects was as follows from the highest to the lowest: Osmanthus asiaticus, Camellia japonica, Pyacantha angustifolia, Photinia glabra, Pittosporum tobira, Nandina domestica, Euonymus japonica, Chaenomeles lagenaria, Aucuba japonica for. Variegatar. The result of the experiment for noise atteunation has shown that woody plant with thicker leaves were better than those with thinner leaves. Multiple Regression Analysis showed Y = 7.653 + 26.530 X ($R^2$= 0.385). The order for the subjects according to their effects on noise attenuation is as follows from the highest to the lowest: Camellia japonica, Nandina domestica, Pittosporum tobira, Taxus cuspidata, Chaenomeles lagenaria. The noise attenuation level of Camellia japonica was the highest (14.70[dB]), while that of Chaenomeles lagenaria was the lowest (6.80[dB]), and its difference between them was 7.9[dB].

• Korean Journal of Community Nutrition
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• v.11 no.4
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• pp.534-540
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• 2006

Recent studies have shown that environmental, biochemical, nutritional or genetic factors affect bone mineral density (BMD). The purpose of the present study was to investigate the effect of vitamin D receptor (VDR) gentotype and nutritional status on BMD of elderly women living in a rural area. Three hundred thirty five elderly women over 65 years in Asan participated the study. Data for demographic and nutrient intakes were obtained by survey with a two day 24 hr recall method. BMD was measured by broadband ultrasound attenuation (BUA) using quantitative ultrasound (QUS). VDR genotypes of the subjects analyzed with Bsm I restriction enzyme were bb (92%), Bb (7%) and BB (1%). No differences were found between genotypes bb and Bb/BB in age, menopausal age, body mass index and body fat. BUA of bb genotype was higher (62.5 $\pm$ 15.6 dB/MHz) than Bb/BB genotype (56.1 $\pm$ 17.6 dB/MHz) by Student's t-tests. Correlation analyses showed strong negative correlation of BMD and age, but positive correlation with BMI, energy and calcium intake. When subgroup analyses were conducted after stratification by the median calcium intake level (412.9 mg/d), the above median calcium intake group showed significant difference in BUA by VDR genotype while the lower median calcium intake group did not show significant difference. The current study confirmed interaction of calcium intake and VDR genotype in association with BMD. Further nutritional intervention will be needed to improve calcium status of the elderly women living in rural areas.

• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.321-327
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• 2005

A MVC (Multi-view Video Coding) method, which uses both an illumination change-adaptive ME (Motion Estimation)/DC (Motion Compensation) and a 2D (Dimensional) direct mode, is proposed. Firstly, a new SAD (Sum of Absolute Difference) measure for ME/MC is proposed to compensate the Luma pixel value changes for spatio-temporal motion vector prediction. Illumination change-adaptive (ICA) ME/MC uses the new SAD to improve both MV (Motion Vector) accuracy and bit saving. Secondly, The proposed 2D direct mode that can be used in inter-view prediction is an extended version of the temporal direct mode in MPEG-4 AVC. The proposed MVC method obtains approximately 0.8dB PSNR (Peak Signal-to-Noise Ratio) increment compared with the MPEG-4 AVC simulcast coding.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.939-947
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• 2010

The LDPC(Low-Density Parity-Check) code, which is one of the channel encoding methods in IEEE 802.11n wireless LAN standard, has superior error-correcting capabilities. Since the hardware complexity of LDPC decoder is high, it is very important to take into account the trade-offs between hardware complexity and decoding performance. In this paper, the effects of LLR(Log-Likelihood Ratio) approximation on the performance of MSA(Min-Sum Algorithm)-based LDPC decoder are analyzed, and some optimal design conditions are derived. The parity check matrix with block length of 1,944 bits and code rate of 1/2 in IEEE 802.11n WLAN standard is used. In the case of $BER=10^{-3}$, the $E_b/N_o$ difference between LLR bit-widths (6,4) and (7,5) is 0.62 dB, and $E_b/N_o$ difference for iteration cycles 6 and 7 is 0.3 dB. The simulation results show that optimal BER performance can be achieved by LLR bit-width of (7,5) and iteration cycle of 7.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.4
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• pp.18-24
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• 2010

This paper presents the improvement of the field uniformity in a reverberation chamber which can be substitute an anechoic chamber for the electromagnetic interference (EMI) and immunity test. Nowadays, there are many EMI issues due to the increasing use of wireless local area network (LAN), digital multimedia broadcasting (DMB), and mobile internet. With this reason, this paper studied the field characteristics in a reverberation chamber for 2.3 GHz band. In this paper, the finite difference time domain (FDTD) method is used to analyze the field characteristics in a reverberation chamber. To improve the field uniformity in the reverberation chamber, this paper adopted a 2D cubical residue diffuser (CRD) with varying the disposition and number of CRD. For each case, the tolerance and standard deviation of the electric field strength are evaluated. In comparison with the reverberation chamber without any CRD, the reverberation chamber with two CRDs showed improved results; 1.98 dB improvement in standard deviation and 3.6 dB improvement in tolerance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.67-74
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• 2005

In this paper, high LO-RF isolation W-band MIMIC single-balanced mixer was designed and fabricated using a branch line coupler and a $\lambda$/4 transmission line. The simulation results of the designed 94 GHz balun show return loss of -27.9 dB, coupling of -4.26 dB, and thru of -3.77 dB at 94 GHz, respectively. The isolation and phase difference were 23.5 dB and $180.2^{\circ}$ at 94 GHz. The W-band MIMIC single-balanced mixer was designed using the 0.1 $\mu$m InGaAs/InAlAs/GaAs Metamorphic HEMT diode. The fabricated MHEMT was obtained the cut-off frequency(fT) of 189 GHz and the maximum oscillation frequency(fmax) of 334 GHz. The designed MIMIC single-balanced mixer was fabricated using 0.1 $\mu$m MHEMT MIMIC Process. From the measurement, the conversion loss of the single-balanced mixer was 23.1 dB at an LO power of 10 dBm. Pl dB(1 dB compression point) of input and output were 10 dBm and -13.9 dBm respectively. The LO-RF isolations of single-balanced mixer was obtained 45.5 dB at 94.19 GHz. We obtained in this study a higher LO-RF isolation compared to some other balanced mixers in millimeter-wave frequencies.