• Composites Research
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• v.34 no.6
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• pp.412-420
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• 2021

In this study, we measure the initial electrical conductivity of SCF/rubber specimens and SCF/rubber specimens with nickel particles respectively. The corresponding electrical conductivity with compressive strain on the specimens is also measured. Through this experiment, we observed the effects of the volume fraction of carbon fiber, nickel particles and external strain on the electrical conductivity. Experiments show that even a small difference in the volume fraction of SCF plays a major role in the change of the electrical conductivity and that the piezoresistivity increases due to fiber reorientation respond to external strain. In addition, the nickel particles contribute to improving the electrical conductivity in specimens with carbon fibers above the threshold volume fraction. It was confirmed that there is an effect of offsetting the increment in the piezoresistivity caused by the reorientation of carbon fibers according to external strain.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.498-510
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• 2022

Among the various factors that form fonts, the concept of a new Korean font term called Inner Space Width was developed and the effect of changes in fonts applied to readability was analyzed. [Experiment 1] An empirical analysis was attempted on how the Korean-shaped Outer Space Width affects readability among the texts. Among the factors that make up the paragraph, Outer Space Width by letter size, letter size, letter spacing, letter spacing, and letter shape was composed of Yoon Myung-jo 110-160 and Inner Space Width of Yoon Myung-jo 110 was the widest at 26.83%. [Experiment 2] In-depth interviews with experts were conducted to derive factors and evaluation indicators constituting the inner space. Inner Space Width is evaluated as a complex factor that affects preference and fatigue, and is related to understanding and speed. This study empirically reviewed the effect on readability using the concept of Inner Space Width in the absence of existing research on Hangul-shaped fast space, and is expected to be actively used in the development of fonts in the future.

• Journal of Korean Society of Forest Science
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• v.76 no.2
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• pp.119-126
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• 1987

This study was carried out to elucidate the desirable PEG molecular weight and it's blending methods which can promote the dimensional stabilization of Corpus controversa, Quercus variabilis and Prunus sargentii. The results may be summarized as follows: 1. PEG polymer loading in woods was affected by specific gravity of wood. And the PEG polymer loading was satisfactory except in Quercus variabilis, which shows the blending method of PEG V was proper. 2. Bulking coefficiency of PEG V was high in Corpus controversa and Prunus sargentii, and it is necessary to paint or coat water-proofing wood preservative: for high bulking coefficiency of Quercus variabilis. 3. In the treatment of PEG V, the antishrink efficiency of Prunus sargentii was 82.59% and that of Quercus variabilis 62.79%. 4. Dimensional stabilization of hardwoods did not have apparant relation with PEG blending method. 5. Judging from results, PEG-400 and PEG-1000 would be enough for dimensional stabilization of hardwood having high specific gravity if other factors are considered well.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.172.2-173
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• 2003

단백질, 탄수화물, 유지 등과 같은 생고분자를 소재로하여 제조하는 가식성 또는 생분해성 필름은 식품표면을 코팅하거나, 식품의 내부에 사용하여 식품을 외부의 충격으로부터 보호하고 식품의 저장수명을 증가시키는 동시에 수분, 기체 및 용질의 이동을 방지하는 기능을 한다. 이러한 가식성 필름의 소재 중 하나인 전분은 비교적 저가의 재료이고 기체투과를 방지하는 성질은 우수하지만, 탄력성이 적은 단점을 가지고 있다. 생고분자필름의 물리적 강도를 증진시키고 수증기의 투과성을 낮추는 방법으로 단백질과 탄수화물을 복합적으로 사용한다 본 실험에서는 분리 대두 단백질(SPI)과 옥수수 전분을 혼합하여 가식성의 생분해성 필름을 제조하고 이들의 이화학적 특성에 대해 연구하였다. SPI 필름은 SPI 5g에 증류수 100$m\ell$을 가해 glycerol 2g을 첨가해 제조하였으며, 옥수수 전분필름은 옥수수 전분 6g에 증류수 100$m\ell$을 가해 glycerol 1.2g을 첨가해 제조하였다. SPI와 옥수수 전분의 혼합필름은 SPI와 옥수수 전분의 양을 1：1 비율로 혼합하여 제조하였다. SPI 필름, 옥수수 전분 및 SPI와 옥수수 전분 용액의 혼합필름의 각각의 수증기 투과도는 7.49$\times$$10^{-11}$, 2.69$\times$$10^{-11}$, 4.24$\times$$10^{-11}$ g.m/m$^2$.s.Pa이었다. 본 실험으로 SPI의 단일재료로만 필름을 제조하였을 때보다 SPI 용액에 옥수수 전분용액을 혼합해 필름을 제조하면 탄력성을 유지하면서 수증기 투과도를 낮출 수 있다는 결과를 얻을 수 있었다.현미밥의 유리아미노산 분석 결과 필수아미노산을 포함한 다량의 아미노산이 존재하였으며 혈압강하 기능성 성분인 GABA(${\gamma}$ -amino butyric acid) 함량은 현미가 4.7 mg/100 g, 발아현미 20.8 mg/100 g이었으며, 동결건조 후 분석한 발아현미밥의 GABA 함량은 5.7 mg/100 g이었다. 발아현미밥의 관능검사 결과는 색, 윤기, 맛, 부착성, 응집성, 탄력성이 A가 유의적으로 높았으며, 외관의 경우도 A가 더 높은 평가를 받았다. 또한 전반적으로 A가 B에 비해 유의적인 차이를 나타내진 않았지만 더 나은 선호도를 나타내었다.좋게 평가되었다.＊값은 63-68사이로, a＊값은 0.13에서 -0.89사이를 b＊값은 2-5값 사이에서 변화하여 제조한 죽의 색이 옅은 황색임을 알 수 있었다. 고형분 함량, 퍼짐성과 pH에 대한 $R^2$은 각각 0.4280, 0.5433과 0.2406임을 볼 때 버섯, 당근, 대파의 비율에 따라 제조한 쇠고기 야채 쌀죽의 고형분 함량, 퍼짐성과 pH는 설정된 범위내에서 그 유의성이 인정되지 않아 큰 영향을 미치지 않음을 알 수 있었다. 관능검사 결과, 색과 향에 대한 반응표면 회귀식의 $R^2$은 각각0.6000과 0.7825이고 P-value는 각각 0.4290과 0.0942로서 5% 수준에서 유의한 상관성이 없음을 확인할 수 있었다. 맛과 점성에 대한 $R^2$은 0.8717과 0.8068이고 P-value는 각각 0.0195 (p ＜0.05)와 0.0612로서 야채의 배합비에 따라 맛에 있어서 유의확률 5%수준에서 그 유의성이 인정되었으며, 전체적인 기호도에 대한 유의성은 $R^2$이 0.8463이고 P-value는 0.034

• Journal of the Korean Applied Science and Technology
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• v.26 no.1
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• pp.24-28
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• 2009

본 논문에서는 청색 인광 발광 물질인 bis(3,5-Difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium (III) (Flrpic)과 녹색 인광 발광 물질인 fac-tris(2-phenypyridine) irdium(III) ($Ir(ppy)_3$)와 적색 인광 발광 물질인 his(5-benzoyl-2-phenylpyridinato-C,N)iridium(III) (acetylacetonate) ($(Bzppy)_{2}Ir(acac)$)를 각각 적층하여 백색 유기 발광 다이오드를 제작하였고, 각각의 발광층 사이에 혼합된 스페이서인 4,4'-N,N'-dicarbazole-biphenyl (CBP):4,7-diphenyl-1,10-phenanthroline (BPhen)을 적층하여 그 때의 영향에 대하여 연구하였다. 최적화된 구조에서의 전력 효율은 $0.014\;mA/cm^2$에서의 19.7 lm/w를 나타내었으며, $0.127\;mA/cm^2$에서의 11.5%의 외부 양자 효율을 나타내었고, 8 V에서 Commission Internationale do I'Eclairage ($CIE_{x,y}$) coordinates (x=0.36, y=0.44)의 색좌표를 나타내었다.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.1-6
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• 1997

In case of using the electrical apparatus in the hazardous atmosphere which exist flammable gas mixtures, There is a dangerosity of gas explosion accident by the electrical spark. The most general method to prevent the explosion by the spark is to use the flame-proof type electrical apparatus to isolate the ignition source. from the flammable atmosphere. But actualy it is impossible to isolate the ignition sources from the atmosphere. So it was needed to find the safe gap which prevent ignition of flammable atmosphere by transmission of flame or heat when a flammable gas mixture exploded inside the apparatus. In this study we tried to find the maximum experimental safe gap(MESG) of $H_2$-air, and $CH_4$-air mixtures by using the 8 litre spherical vessel with 25mm flange. The experiment parameter were ignition position, concentration and initial pressure before explosion. From the experiment the ignition position was affected to the MESG. MESG value was minimum near the stoichiometric concentration of gas mixtures, and according to the increase of initial pressure MESG was decreased.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.442-448
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• 2009

To evaluate the combustion mechanism of each droplet cluster downstream of the premixed spray flame, the simultaneous time-series measurements were conducted by using optical measurement system consisting of laser tomography, multi-color integrated Cassegrain receiving optics (MICRO) and phase Doppler anemometer (PDA). Furthermore, the group combustion number of droplet cluster was estimated experimentally, and the combustion mechanism of droplet cluster was examined applying the theoretical analysis. The group combustion number, $G_c$, was experimentally estimated about all droplet cluster verified by planar images, and it was classified into the internal group combustion mode and the external group combustion mode according to the theoretical analysis. It is found that there are cases in which the group combustion number estimated experimentally for droplet cluster agree or disagree with the classification by theoretical analysis. The reason of disagreement is considered due to that the group combustion number was only estimated by the geometrical arrangement of droplets in cluster, and that the actual phenomenon is three-dimensional but the measurement system is two-dimensional.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.7
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• pp.315-321
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• 2014

In this study, external condensation heat transfer coefficients (HTCs) of two non-azeotropic refrigerant mixtures of HFC32/HFC152a at various compositions were measured on both 26 fpi low-fin and Turbo-C enhanced tubes, of 19.0 mm outside diameter. All data were taken at the vapor temperature of $39^{\circ}C$, with a wall subcooling of 3~8 K. Test results showed that the HTCs of the tested mixtures on the enhanced tubes were much lower than the ideal values calculated by mass fraction weighting of the pure component HTCs. Also, the reduction of HTCs due to the diffusion vapor film was much larger than that of a plain tube. Unlike HTCs of pure fluids, HTCs of the mixtures measured on enhanced tubes increased, as the wall subcooling increased, which was due to the sudden break-up of the vapor diffusion film with an increase in wall subcooling. Finally, the heat transfer enhancement ratios for mixtures were found to be much lower, than those of pure fluids.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.561-566
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• 2019

In the Internet space, integrity and security must be maintained for secure and confidential communication, which ensures reliability between sender and receiver. Cryptography is an important factor in maintaining robustness against external attacks. For this purpose, encryption and steganography methods are used. Steganography is a method of hiding confidential information without making statistically significant changes to digital media. I propose a method of transforming the Hangul-Jamo consisting of choseong, jungseong and jongseong, and inserting them into RGB pixel values of the cover image. In order to improve security, a new blending method was used to hide the altered information in the lowest region. In this case, a mixture of LSB and LDR techniques was applied. PSNR was calculated for image quality. The PSNR of the proposed method is 43.225dB, which satisfies the lowest level.

• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.15-24
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• 2010

In the case of underground power utilities pipe such as circular pipe, the most difficult problem is low compaction efficiency of the bottom of pipe inducing the failure of utilities. To overcome this problem, various studies have been performed and one of these is CLSM(Controlled Low Strength Materials) accelerated flow ability. But underground power utilities pipe backfill materials is also needed to have good thermal property that can dissipate the heat as rapidly as it is generated. So, in this study, we performed thermal resistancy test for various materials such as sand, weathered soil, clay and mixed soil to analyze the thermal characteristics of CLSM(Controlled Low Strength Materials) with accelerated flow ability for various conditions(water content, unit weight, void ratio, curing time) and to evaluate the applicability for backfill material of underground power utilities pipe. The test results of 16 specimens for thermal resistancy test showed good thermal property that maintained below $85^{\circ}C\;cm/W$.