• 소성∙가공
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• 제32권2호
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• pp.67-73
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• 2023

To overcome a climate change, manufacturing complex-shaped electric mobility parts becomes one of the important issues for enhancing a performance of motor with reducing their weight. Therefore, development of laser-based additive manufacturing shed on light due to their flexible manufacturing capacity that can be suitable to solve the poor formability of Fe-Si alloys for electric mobility parts. Although there are several studies existed to optimize the performance of additively manufactured Fe-Si alloys, the post-annealing effect was not well investigated yet though this is important to control the texture and mechanical properties of additively manufactured parts. In the present work, annealing effect on the mechanical property and microstructure of additively manufactured Fe-4.5Si alloy was investigated. Because of the ordered phase initiation after annealing, the hardness of additively manufactured Fe-4.5Si alloy increased up to 1173 K while a hardness drop occurs at the 1273 K condition due to the micro-crack initiation. The response surface methodology result represents the 1173 K-5 h sample is an optimal condition to maximize the mechanical property of additively manufactured alloy without micro-cracks.

• 생명과학회지
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• 제23권9호
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• pp.1126-1132
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• 2013

CYP2J2 효소는 간외의 조직에 존재 하는 효소로써, 주로 심혈관계에 발현되어 있다. CYP2J2는 내인성 대사체 및 여러 치료 약물들의 대사에 중요한 작용을 하고 있다. 또한 CYP2J2는 인체의 종양조직이나 종양 세포주에서 과발현되어 있어, 종양 치료를 위한 새로운 표적이 되고 있다. 본 연구에서는 천연물 10종을 대상으로 시토크롬 2J2 동효소에 저해능을 가지는 화합물을 발굴하고자 하였다. 10종의 천연물 중 thelephoric acid는 CYP2J2에 의해 매개되는 에바스틴($IC_{50}=5.32{\mu}M$), 아스테미졸($IC_{50}3.23{\mu}M$) 및 터페나딘($IC_{50}=3.27{\mu}M$) 대사를 강력하게 저해하였다. 향후, 이 약물을 대상으로 한 항암 활성 평가가 필요할 것으로 판단된다.

• 전자통신동향분석
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• 제32권4호
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• pp.89-95
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• 2017

영국은 2017년 3월 5G N/W 조기구축을 위한 정부차원의 전략방향 보고서(A 5G Strategy for UK)를 발표하였다. 영국은 5G 인프라가 4차 산업혁명의 촉진제 역할을 할 것이며, 5G로 인한 경제적 파급 효과가 2030년경에 1,980억 파운드 달할 것으로 예상한다. 이러한 전망에 따라 영국 정부는 5G 테스트베드 구축, Small Cell 및 백홀 구축 지원, 주파수 정책방향 제시 등 5G N/W 조기구축 환경을 조성하여 이동통신사의 적극적인 투자를 유인할 계획이다. 아울러 산업계, 학계, 지역정부와 협력하여 다양한 산업분야에서의 5G 활용 방안을 도출하며, 5G 상용화 이전에 해결해야 할 과제를 정비함으로써 영국이 5G 분야에서 글로벌 리더가 되고자 하는 목표를 제시하고 있다. 본고에서는 영국이 4차 산업혁명에 대비하여 제시하는 5G N/W 투자 촉진 전략을 소개하고자 한다.

• 전자통신동향분석
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• 제32권5호
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• pp.65-73
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• 2017

A holography technique optically reconstructs a three-dimensional object in space to provide a natural sense of depth and volume to the observer, thereby providing an ultimate 3D image capable of solving the problem of "vergence-accommodation conflict" occurring in a conventional stereoscopic imaging system. In this paper, we present a technical framework for measuring the performance and evaluating the quality of a holographic display, which enables a quantitative measurement of the optical and physical properties that affect the performance and quality of a holographic display. In addition, we provide the trend regarding standardization related to holographic display measurements. Although this trend has barely started, research activities related to holographic display measurements and quality evaluations are expected to grow in the near future.

• 한국식품영양학회지
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• 제32권6호
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• pp.620-629
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• 2019

To examine the possibility of ear mushroom (EM) as a source of natural vitamin D, the UVB (ultraviolet B) was treated according to sample drying status, drying methods before UVB treatment and harvest time. And then, vitamin D₂ and ergosterol contents were investigated. According to the sample drying status, the vitamin D₂ contents of fresh and freeze-dried EM (whole) increased to 4,634.4~4,780.9 ㎍/100 g D.W. (dry weight) under UVB dose 52.5~70.0 kJ/㎡ and above 18,693.1 ㎍/100 g D.W. under above 105 kJ/㎡, respectively. By drying methods before UVB treatment, vitamin D₂ contents of EM powder (below 500 ㎛) that dried in the vinyl house and freeze-dryer increased to 4,886.2~5,132.9 ㎍/100 g D.W. under above 105 kJ/㎡ and 17,103.7 ㎍/100 g D.W. under 70 kJ/㎡, respectively. Ergosterol content decreased with increasing UVB dose in all experiments. According to the harvest time, vitamin D₂ content under UVB dose 210 kJ/㎡ showed marked difference and in order of June, July, August, October and April. As for the results, the optimum harvest time, drying method before UVB treatment, sample size, UVB dose for the EM contained high vitamin D₂ content were June, freeze-drying, whole, and 105 kJ/㎡, respectively.

• Journal of Biosystems Engineering
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• 제32권5호
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• pp.332-338
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• 2007

Yield mapping is necessary for precision farming. An on-site rice weighing system for a head-feed combine was developed to measure the total weight of rice grain harvested while the combine was operated. A load cell system was used to monitor rice weights accumulated into the combine grain tank using a load cell. This method gave cumulative grain weight readings as a function of time. The system consisted of a load cell, two supporting brackets, and a computer-based data acquisition system. The weights measured with the system from two fields were compared with those obtained with a commercially available electronic balance. The response of the load cell to varying grain weights was linearly modeled, showing a coefficient of determination of 0.998 and a standard error of ${\pm}4.09kg$.

• Journal of Welding and Joining
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• 제29권4호
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• pp.80-84
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• 2011

In the 5xxx series Al-Mg alloy, magnesium addition can increase the strength of aluminum alloy by solid solution strengthening but it has a relatively low melting and boiling temperature. During full -penetration laser welding of the Al-Mg alloys, its low boiling point and high vapor pressure brings about the spiky humping bead on the bottom side. Under back-side shielding, the spiking of back bead can be reduced but it restraints the process flexibility. In this study, a square pulse waveform modulation was employed to stabilize keyhole and back bead surface without back-side shielding. By using an experimental design, the bead shapes were evaluated for various process parameters such as the focal position, welding velocity and waveform parameters and the smooth back bead shape could be achieved.

• Nutrition Research and Practice
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• 제15권5호
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• pp.604-612
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• 2021

BACKGROUND/OBJECTIVES: We aimed to investigate the association of waist circumference (WC) with body composition among individuals with a normal body mass index (BMI) to distinguish muscle and fat mass, as both affect health differently. SUBJECTS/METHODS: We analyzed dual-energy X-ray absorptiometry data (derived from the Korean National Health and Nutrition Survey, which includes information on fat and lean mass) of 7,493 adults with a normal BMI. Subjects were categorized into four groups of increasing WC. The fourth group was defined as being centrally obese. Each number of subjects are as follows: 1,870, 695, 231, and 39 among men and 3,054, 1,100, 406, and 98 among women. We conducted a sex-stratified linear regression analysis of body composition according to WC group after adjustments for covariates. RESULTS: We observed a positive association of body fat with increasing WC in both men and women (all P for trend: < 0.001). The adjusted mean values for percent body fat with 95% confidence intervals (CIs) according to the four WC groups in ascending order were 17.8 (17.5-18.3), 21.0 (20.6-21.5), 22.1 (21.5-22.8), and 25.1 (24.2-26.1) in men and 29.7 (29.4-30.0), 32.0 (31.6-32.3), 32.9 (32.4-33.4), and 34.7 (33.2-36.1) in women. However, there was an inverted J-shaped association between muscle mass and WC. The fourth group had a higher percent body fat and lower muscle mass than other groups. The adjusted mean values for appendicular skeletal muscle mass index (kg/m²) with 95% CIs according to the four WC groups in ascending order were 7.55 (7.51-7.59), 7.62 (7.56-7.68), 7.65 (7.56-7.74), and 7.22 (7.04-7.41) in men and 5.83 (5.80-5.85), 5.96 (5.92-6.00), 6.03 (5.96-6.10), and 5.88 (5.73-6.03). CONCLUSIONS: There was a positive association between body fat and WC among individuals with normal BMI; conversely there was an inverted J-shaped association between lean body mass and WC. Our findings support the WC measurement should be included in obesity evaluations for adults with a normal BMI.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.505-508
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• 2001

Currently there is much interested in removing latent charge that is caused to latent image effect and blurring of obtained image as well as reduction of x-ray conversion efficiency in digital radiography system. To remove latent charge a-Se film is irradiated by light with 3500 lux using halogen lamp and optical fiber. We measured dark current and photosensitivity to analyze removing effect of latent charge, then compared with and without light erasing method. The reduction of measured signal due to latent charge effect was 32.5 %, and the removal effect of latent charge by using light erase method was its 95.5 %.

• 전자통신동향분석
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• 제16권5호통권71호
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• pp.21-32
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• 2001

요즘 인터넷을 이용한 무료 전화가 각광을 받고 있고, 이와 같은 무료 인터넷폰 서비스를 실현 가능하게 한 것이 바로 VoIP 기술이다. 예전에는 웹에서 웹으로의 통화 방식만을 지원했으나, 지금은 일반전화로의 통화뿐만 아니라 지능망 서비스, 이동 전화 통화까지 지원하는 등 VoIP를 이용한 음성 통화가 제공하는 서비스의 폭이 커지고 있다. 따라서 본 고는 인터넷폰 서비스 제공을 위한 인터넷과 공중전화망의 연동 개념을 확립하고 해당 통신망 연동에 있어서의 기술 요구 조건을 도출함으로써, 인터넷폰 서비스 이용자의 보호를 위한 적정 수준의 서비스 품질 확보 방안을 제시하고자 한다.