• 한국초지조사료학회지
• /
• 제9권3호
• /
• pp.158-162
• /
• 1989

This experiment was conducted to evaluate individual difference of chewing speed and chews per bolus duing the rumination using twenty three heads of grazing cattle and thirty six heads of barn feeding cattle. Rumination behaviour was measured and recorded by the masster EMC telemeter and visual observation. The chewing speed (chews/lOOsec) was significantly different individually (C.V. 13.0-14.5 %) among the variable aged group (1-60 months), but that of same aged group showed lower difference (C.V. 4.5 %). The chews per bolus showed even larger individually difference than the chewing speed, so the variable aged group (1-60 months) resulted the 15.5-16.2 %of C.V.and the same aged group showed the 9.5 % of C.V. Under 12 month aged cattle showed more rapid chewing speed than older aged cattle. The chewing speed changed with the growth of cattle, but the chews per bolus did not show any relationship with age, so it is regarded as the individually characteristic pattern.

• 대한기계학회논문집
• /
• 제19권4호
• /
• pp.896-907
• /
• 1995

Titanium 6242(.alpha. + .betha.) alloy has a good strength/weight ratio and is used for aircraft components such as engine disks and compressor blades. When this material is forged at an elevated temperature, the process parameters should be carefully controlled because the process window of this material is quite narrow. In the present investigation, a rigid-thermoviscoplastic finite element method is used to predict the deformation behavior and temperature/strain distributions in an engine disk during near-net shape hot forging. The purpose of the investigation is to obtain a proper ram speed profile, assuming the hydraulic press used in the forging is capable of varying ram speed during loading. In result, it was found that the ram speed at constant strain-rate of 0.5/sec shows a sound deformation behavior, a relatively uniform deformation and a good temperature distribution. This information is also valuable in predicting resulting microstructures in the disk.

• 한국ITS학회 논문지
• /
• 제16권5호
• /
• pp.121-133
• /
• 2017

1990년대 중반 이후 어린이보호구역 개선사업 등 학교 주변 안전과 보행환경 개선을 위한 정책이 적극적으로 추진되어 왔으나, 어린이 통학 시의 주요 이동경로가 이루어지는 통학로까지는 확대되지 못해 사고예방 효과가 크지 않았다. 또한 자동차 급증으로 첨두시간대의 간선도로 교통이 이면도로로 우회함에 따라 어린이들의 주요 생활공간인 학교 권역까지 침범하는 등 어린이 안전과 환경을 위협하고 있다. 이에 본 연구는 국내 어린이 교통사고 특성을 파악하고 서울시 여의도 중고등학교 및 경기도 운중초등학교를 중심으로 현장조사를 수행하여 문제점을 분석하였다. 또한 보행자 보호구역(어린이보호구역 포함)에 가변형속도제한표지 및 비콘을 설치하여 해당시설이 차량의 통행속도에 미치는 영향을 분석하였다. 분석결과 가변형속도제한표지는 약 8.3km/h의 통행속도 감속효과가 나타났으며 비콘의 경우 미미하나마 오히려 0.8km/h의 통행속도가 증가하는 현상이 도출되었다. 또한 설치전후의 신호위반 차량대수를 조사한 결과 승용차, 버스, 화물차의 신호위반율이 약 3% 감소하였다.

• 한국정밀공학회지
• /
• 제17권12호
• /
• pp.185-194
• /
• 2000

Rapid Prototyping(RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stacking, low build speed caused by line-by-line solidification to build one layer, and additional post processing to improve surface roughness, so it is required very high cost to introduce and to maintain of RP apparatus. The objective of this study is to develop a new RP process, Variable Lamination Manufacturing using linear hotwire cutting technique and expandable polystyrene foam sheet as part material(VLM-S), and to investigate characteristics of part material, cutting characteristics by using linear hotwire cutting system and bonding. Experiments were carried out to investigate mechanical properties of part material such as anisotropy and directional tensile strength. In order to obtain optimal dimensional accuracy, surface roughness, and reduced cutting time, addition experiments were performed to find the relationship between cutting speed and cutting offset of hotwire, and heat generation of hotwire per unit length. So, adhesion strength tests according to ASTM test procedure showed that delamination did not occur at bonded area. Based on the data, a clover-shape was fabricated using unit shape part(USP) it is generated hotwire cutting. The results of present study have been reflected on the enhancement of the VLM-S process and apparatus.

• 융합신호처리학회논문지
• /
• 제10권3호
• /
• pp.158-163
• /
• 2009

LMS(Least Mean Square) 알고리즘은 식이 간단하고 계산량이 비교적 적기 때문에 널리 사용되고 있다. 그러나 LMS 알고리즘은 수렴속도를 높이게 되면 주위 환경이 급격하게 변하는 경우 발산하게 되고, 안정성을 높이게 되면 수렴속도가 떨어지는 수렴속도와 안정성 사이에 trade-off가 발생한다. 이러한 LMS 알고리즘의 단점을 개선하기 위해 VSSLMS(Variable Step Size LMS) 알고리즘이 개발되었다. VSSLMS 알고리즘은 에러 신호를 이용하여 스텝사이즈를 조절하여 수렴속도와 성능을 동시에 향상시킨다. 본 논문에서는 실시간 환경에서 적응잡음 제거기의 성능을 개선시키기 위해 I-VSSLMS(Instantaneous Signal to Noise Radio VSSLMS)을 제안한다. 제안한 I-VSSLMS을 TMS320C6713 DSP 보드를 이용하여 적응 잡음 제거기에 적용하여, 실시간으로 시뮬레이션을 하였고, 각 알고리즘의 성능을 비교 분석하여 제안한 알고리즘의 성능이 우수함을 입증하였다.

• Preventive Nutrition and Food Science
• /
• 제17권3호
• /
• pp.203-209
• /
• 2012

The effects of variable moisture content, screw speed and barrel temperature on the physicochemical properties of red ginseng powder extrudates were investigated. The raw red ginseng powders were processed in a co-rotating intermeshing twin-screw extruder. Primary extrusion variables were feed moisture content (20 and 30%), screw speed (200 and 250 rpm) and barrel temperature (115 and $130^{\circ}C$). Extruded red ginseng showed higher crude saponin contents (6.72~7.18%) than raw red ginseng (5.50%). Tested extrusion conditions did not significantly affect the crude saponin content of extrudates. Increased feed moisture content resulted in increased bulk density, specific length, water absorption index (WAI), breaking strength, elastic modulus and crude protein content and decreased water solubility index (WSI) and expansion (p<0.05). Increased barrel temperature resulted in increased total sugar content, but decreased reducing sugar content in the extrudate (p<0.05). Furthermore, increased barrel temperature resulted in increased amino acid content and specific length and decreased expansion and bulk density of extrudates only at a higher feed moisture content. The physicochemical properties of extrudates were mainly dependent on the feed moisture content and barrel temperature, whereas the screw speed showed a lesser effect. These results will be used to help define optimized process conditions for controlling and predicting qualities and characteristics of extruded red ginseng.

• Korean Journal of Acupuncture
• /
• 제36권4호
• /
• pp.252-263
• /
• 2019

Objectives : This research aimed to 1) analyze the true meanings of the chapter, 'Wigi Haeng (Wei Qi Xing), the movement of guard qi' in Youngchu (Ling Shu) from the point of view of ancient Chinese Astronomy, 2) calculate the speed of Wigi over 24 Chinese seasons, 3) analyze the true meaning of daytime and nighttime in the chapter. Methods : 1) The chapter 'Wigi Haeng' was analyzed using concepts of ancient Chinese astronomy, 2) the records of angular distances of 28 constellations in the Book of Han (Han Shu) were used to analyze the meanings, and 3) the records of lengths of daytime and nighttime in the Book of Hou Han (Hou Han Shu) were used to calculate the speed of Wigi. Results : 1) The author of the chapter 'Wigi Haeng' did not consider the irregularity in the angular distances of the 28 Chinese constellations (Su). 2) The commentary in the Huangjenaegyong Taeso (Huang Di Nei Jing Tai Su) about the constellations in the chapter is correct. 3) The speed of Wigi changes in daytime and nighttime depending on the seasons. 4) When the speed of Wigi increases in daytime, the speed in nighttime decreases, and vice versa. 5) The beginning of daytime in 'Wigi Haeng' is not the time of sunrise but the time of dawn (2.5 Gak before sunrise). The nighttime ends 2.5 Gak after sunset. Conclusions : 1) The chapter 'Wigi Haeng' demonstrates the ancient astronomical point of view on the universe and the movement of Wigi. The speed of Wigi is variable. 2) This chapter does not address the irregularity in the angular distances of the 28 Su. 3) More research is needed on the meaning of daytime and nighttime in 'Wigi Haeng'.

• 디지털콘텐츠학회 논문지
• /
• 제19권7호
• /
• pp.1313-1322
• /
• 2018

본 연구는 프랜차이즈 가맹점에서 제공하고 있는 무인점포의 이용의도를 알아보고자 실증 분석하여 검정하였다. 무인점포의 독립변수들로는 크게 기술기반셀프서비스, 점포특성으로 나누어 변수를 선정하였다. 기술기반셀프서비스의 편리성, 신속성, 점포특성의 기능성, 적합성 그리고 무인점포의 비용을 선정하였다. 기대일치이론을 활용하여 매개변수에 기대일치, 만족 최종적으로 종속변수는 이용의도를 선정하였다. 무인점포를 사용하는 대상으로 설문지를 배포하여 총 181명을 활용하였다. 분석결과, 편리성, 신속성, 기능성, 적합성은 기대에 긍정적인 영향을 미쳤으며, 만족에는 편리성과 적합성 변수만이 긍정적인 영향을 미치는 것으로 나타났다. 비용은 이용의도에 영향을 미치지 못하는 것으로 나타났으며, 최종적으로 기대일치, 만족은 이용의도에 긍정적인 영향을 미치는 것으로 검증이 되었다.

• 한국대기환경학회지
• /
• 제14권5호
• /
• pp.397-410
• /
• 1998

Tracer experiments were performed 4 times in December 1992 on the relatively flat terrain and nearby building area adjacent to the Taedok Science Town in Korea. Each experiment was continued for relatively short period of 1 or 2 hours with intermittent release of SF6 up to 2.07g/s at 10m height. Movement of tracer plume was tracked by a continuous tracer analyzer installed on an air monitoring van. Simulation with INPUFF was carried out to analyze and predict experiments. Measured profiles of tracer plume were narrow and sharp while predicted profiles by INPUFF were broad and slowly varied. Tracer plumes were detected at a short distance of 0.5 to 2.2 km mainly due to intermittent release and high value of lower detectable limit. Various experimental conditions were tested by INPUFF simulation in order to find desirable conditions. Higher wind speed and less variable wind direction could yield longer distance of plume tracking only when the lower detectable limit was sufficiently low. Distance of plume tracking was long and did not much depend on the lower detectable limit in stable atmospheric conditions.

• 한국해양공학회지
• /
• 제29권5호
• /
• pp.366-372
• /
• 2015

Ocean energy is one of the most promising renewable energy resources. In particular, South Korea is one of the countries where it is economically and technically feasible to develop tidal current power plants to use tidal current energy. In this study, based on the design code for HARP_Opt (Horizontal axis rotor performance optimizer) developed by NREL (National Renewable Energy Laboratory) in the United States, and applying the BEMT (Blade element momentum theory) and GA (Genetic algorithm), the optimal shape design and performance evaluation of the horizontal axis rotor for a 200-kW-class tidal current turbine were performed using different numbers of blades (two or three) and a pitch control method (variable pitch or fixed pitch). As a result, the VSFP (Variable Speed Fixed Pitch) turbine with three blades showed the best performance. However, the performances of four different cases did not show significant differences. Hence, it is necessary when selecting the final design to consider the structural integrity related to the fatigue, along with the economic feasibility of manufacturing the blades.