• Journal of the Korean Wood Science and Technology
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• 제52권4호
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• pp.331-342
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• 2024

Rubberwood (Hevea brasiliensis) has excellent physical and mechanical properties and is one of the most widely used species in Southeast Asia. However, it has poor resistance to subterranean termite attacks due to its high sugar and starch contents. The objective of this study was to evaluate the termite resistance of experimental wood-plastic composite (WPC) panels manufactured from rubberwood flour, polyethylene terephthalate, and silica in three different weight ratios (1/2/7, 1/3/6, and 1/4/5). The panels were exposed to Coptotermes curvignathus subterranean termites in a no-choice test under laboratory conditions based on Indonesian standards. Solid rubberwood used as control samples presented poor resistance, exhibiting 23.1% weight loss due to subterranean termite attack, as indicated by low termite mortality and high wood weight loss. In contrast, the WPC samples demonstrated extreme resistance, with weight loss ranging from 0.19% to 0.23%. Based on the findings of this study, the high termite mortality and overall low mass loss of the samples indicate that such manufactured panels could provide a high level of protection with regard to Indonesian standards.

• 한국산학기술학회논문지
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• 제22권6호
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• pp.275-282
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• 2021

Maleic anhydride (MA)와 divinylbenzene (DVB)을 개시제인 di(tert-butyl-perxoyisopropyl)benzene (PK-14)과 함께 이축 압출기에서 용융 그래프팅 반응을 통해 상용화제인 high-molecular-weight maleic anhydride-grafted polylactic acids (HMMA-g-PLA)를 제조하였다. 제조된 HMMA-g-PLA의 특성을 분석하기 위해 Fourier transform infrared (FTIR), Melt index (MI), 그리고 역적정을 실시하였다. HMMA-g-PLA는 DVB의 함량이 증가함에 따라 MA의 그래프팅율은 증가하나 MI는 감소하였는데, DVB의 도입으로 PLA의 𝛽-scission 반응이 억제되어 분자량이 증가되었기 때문이다. HMMA-g-PLA를 사용한 PLA기반 합성목재(wood-plastic composites, WPCs)는 matrix인 PLA에 보강재인 목재와 무기 충전재인 talc를 첨가하여 일축 압출기로 용융 블렌드하였다. 상용화제인 HMMA-g-PLA가 도입된 WPCs는 도입되지 않은 WPCs와 비교하여 더 높은 굴곡강도 및 충격강도를 보였다. 이것은 Scanning electron microscope (SEM) 분석을 통해 HMMA-g-PLA의 첨가로 PLA와 목분과의 계면 결합력이 우수해졌기 때문인 것을 알 수 있었다. 하지만 HMMA-g-PLA의 함량이 높을 때는 WPCs의 기계적 물성을 악화시켰다. 이는 도입된 HMMA-g-PLA 상용화제의 분자량이 PLA 고분자 수지보다 더 낮아 기계적 물성을 감소시킨 것으로 판단하였다.

• 정보와 통신
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• 제30권11호
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• pp.52-59
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• 2013

본고에서는 무선전력전송 국제표준 기술 동향과 산업 기술 동향에 대해 기술한다. 무선전력전송의 국제표준화는 ISO/IEC JTC1 SC6 그룹과 IEC TC100 TA15 그룹에서 진행 중이며, 산업 표준화는 WPC, A4WP, PMA를 중심으로 진행 중이다. 국제표준화기구에서는 인밴드 제어 프로토콜과 다수기기 및 다수 충전기 관리 프로토콜에 관한 국제표준화가 추진 중이고, 산업협의체에서는 제품 개발을 위해 송수신 시스템 및 제어 프로토콜에 관한 규격화를 추진 중이다. 향후, 산업표준 간의 호환성 유지를 위한 표준 개발이 절실히 필요하다.

• 한국축산식품학회지
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• 제40권1호
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• pp.118-131
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• 2020

It is necessary to add protective agents for protecting the probiotic viability in the preparation process of probiotics starter. In this study, we used whey protein concentrate (WPC), pullulan, trehalose, and sodium glutamate as the protective agent and optimized the proportion of protective agent and spray-drying parameters to achieve the best protective effect on Lactobacillus plantarum. Moreover, the viable counts of L. plantarum in starter stored at different temperatures (-20℃, 4℃, and 25℃) for 360 days were determined. According to response surface method (RSM), the optimal proportion of protective agent was 24.6 g/L WPC, 18.8 g/L pullulan, 16.7 g/L trehalose and 39.3 g/L sodium glutamate. The optimum spray-drying parameters were the ratio of bacteria to protective agents 3:1 (v: v), the feed flow rate 240 mL/h, and the inlet air temperature 115℃ through orthogonal test. Based on the above results, the viable counts of L. plantarum was 12.22±0.27 Log CFU/g and the survival rate arrived at 85.12%. The viable counts of L. plantarum stored at -20℃ was more than 10¹⁰ CFU/g after 200 days.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.41-45
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• 2016

The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system.

• 한국축산식품학회지
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• 제37권1호
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• pp.62-70
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• 2017

The aim of this study was identifying a suitable food grade enzymes to hydrolyze whey protein concentrates (WPCs), to give the highest bioactivity. WPCs from ultrafiltration retentate were adjusted to 35% protein (WPC-35) and hydrolyzed by enzymes, alcalase, ${\alpha}-chymotrypsin$, pepsin, protease M, protease S, and trypsin at different hydrolysis times (0, 0.5, 1, 2, 3, 4, and 5 h). These 36 types of hydrolysates were analyzed for their prominent peptides ${\beta}-lactoglobulin$ (${\beta}-Lg$) and ${\alpha}-lactalbumin$ (${\alpha}-La$), to identify the proteolytic activity of each enzyme. Protease S showed the highest proteolytic activity and angiotensin converting enzyme inhibitory activity of IC50, 0.099 mg/mL (91.55%) while trypsin showed the weakest effect. Antihypertensive and antioxidative peptides associated with ${\beta}-Lg$ hydrolysates were identified in WPC-35 hydrolysates (WPH-35) that hydrolyzed by the enzymes, trypsin and protease S. WPH-35 treated with protease S in 0.5 h, responded positively to usage as a bioactive component in different applications of pharmaceutical or related industries.

• Composites Research
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• 제26권3호
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• pp.170-174
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• 2013

상온 상압 플라즈마 표면처리된 목분을 폴리프로필렌(polypropylene)과 혼합하였을 때 두 재료의 계면에 미치는 영향을 연구하였다. 목분과 폴리프로필렌을 압출기를 통해 기계적으로 혼합한 후 사출기를 이용하여 목분함유량 50 wt% 목분/폴리프로필렌(Wood Plastic Composite, WPC) 복합재를 제조하였다. 플라즈마 표면처리 공정에 가장 적합한 Monomer(모노머)를 찾기 위해 Oxygen, Benzene, CH-4, Acrylic-acid, Hexafluoroethane, Trifluorotolune, Hexamethyl-disiloxane(HMDSO) 등 7가지의 모노머에 대해 Contact angle(접촉각)을 측정하여 표면에너지를 계산하였다. 그 결과 HMDSO가 가장 높은 표면에너지를 나타내어 플라즈마 공정의 모노머로 적용하였다. 소수성인 폴리프로필렌과 친수성인 목분을 플라즈마 표면처리를 통하여 목분의 표면을 개질하였고 두 재료의 계면 결합력을 향상시킬 수 있었다. 기계적 물성평가 결과는 인장강도의 경우 최대 7.59%, 굴곡강도의 경우 최대 12.43%가 증가하였다. SEM(Scanning Electron Microscope)을 이용하여 파단면을 관찰하였고 플라즈마 표면처리의 효과를 확인하였다.

• Journal of Dairy Science and Biotechnology
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• 제41권3호
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• pp.113-125
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• 2023

In this study, we explored the synergistic effects of whey protein concentrate (WPC) and soybean protein components after fermentation with lactic acid bacteria isolated from kimchi, and identified several peptides with desirable physiological functions, proteolysis, and immune effects. Antioxidant activity was determined using 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid, 1,1-diphenyl-2-picrylhydrazyl, ferric-reducing antioxidant power, and hydroxyl radical scavenging assays, followed by cross-validation of the four antioxidant activities. These assays revealed that samples with a 8:2 and 9:1 whey to soy ratio possessed higher antioxidant activity than the control samples. Antibacterial potency testing revealed high antibacterial activity in the 9:1 and 8:2 samples. Cytotoxicity testing of samples using 3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide revealed that only the 10:0, 1:9, and 0:10 samples had <80% viable cells, indicating no significant cytotoxicity. Nitric oxide (NO) assays revealed that NO expression was reduced in 8:2, 5:5, and 0:10 protein ratio fermentations, indicating low inflammatory reaction stimulatory potential. Cytokine expression was confirmed using an enzyme-linked immunosorbent assay kit. The 8:2 sample had the lowest inflammatory cytokine (interleukin [IL]-1α, IL-6, and tumor necrosis factor-α) levels compared with the lipopolysaccharide-treated group. Amino acid profiling of the 8:2 sample identified 17 amino acids. These results suggest that inoculating and fermenting Lactobacillus plantarum DK203 and Lactobacillus paracasei DK209 with an 8:2 mixture of WPC and soybean protein releases bioactive peptides with excellent anti-inflammatory and antioxidant properties, making them suitable for functional food development.

• 한국축산식품학회지
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• 제22권1호
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• pp.59-65
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• 2002

이 연구는 Whey배지에 Whey protein concentrate 80% (WPC-80)와 Whey protein isolate(WPI)를 첨가하여 B. bifidum Bb-11의 생장촉진효과를 알아보고자 실시하였다. 또 이 단백질들의 구성성분인 $\alpha$-Lactalbumin과 $\beta$-Lactogluburin을 trypsin으로 처리하여 얻어진 분해물을 분자량에 따라 분획하여 각 분획별로 그 효과를 구명하였으며, 그 결과를 요약하면 다음과 같다. WPC 첨가에 의한 효과는 대조구에 비하여 생장촉진효과가 있는 것으로 나타났으나, 첨가농도에 따른 차이는 근소하였다. WPI는 뚜렷한 생장촉진효과를 보여주지 못하였으며, 첨가량이 많을수록 생장이 억제되었다. 두 종류의 유청단백질을 4$0^{\circ}C$에서 6시간 동안 trypsin처리한 후 UF처리에 의하여 분획하고 각 분획들을 Centricon-30 으로 농축한 후, 얻어진 $\alpha$-lactalbumin 분해물 3분획에 대한 단백질농도는 각각 11.63mg, 7.79mg 및 5.21mg 이었고, $\beta$-Lactoglubulin 분해물 3분획은 각각 4.12mg, 5.30 mg 및 9.35mg 이었다. $\alpha$-Lactalbumin분해물 세 분획 모두 대조구에 비하여 높은 생장촉진효과를 나타내었으며, 그중에서 분자량 10,000~3,000Da(F-II)과 3,000Da 이하(F-III)의 두 분획이 모두 높게 나타난 것으로 보아, 분자량 10,000Da 이하의 peptide들이 bifidobacteria의 생장을 향상시키는 것으로 밝혀졌다. $\beta$-Lactoglubulin 분해물 세 분획들도 대조구에 비하여 생장이 좋게 나타났다. 분자량 10,000Da 이하의 peptide를 함유하는 두 분획은 생장이 우수하였으며 배양 24 시간후에는 분자량 3,000Da 이상의 두 분획(F-I, F-II)이 대조구에 비하여 빠르게 생장이 저하된 반면, 분자량 3,000 Da이하의 분획(F-III)에서는 계속적인 생장촉진효과를 보여주었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1889-1910
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• 2017

This paper investigates a protocol so-called Adaptive Harvest Then Transmit (AHTT) for wireless powered communication networks (WPCNs) in multiple-input single-output (MISO) downlink systems, which assists in transmitting signals from a multi-antenna transmitter to a single-antenna receiver. Particularly, the power constrained relay is supplied with power by utilizing radio frequency (RF) signals from the source. In order to take advantage of multiple antennas, two different linear processing schemes, including Maximum Ratio Combining (MRC) and Selection Combination (SC) are studied. The system outage capacity and ergodic capacity are evaluated for performance analysis. Furthermore, the optimal power allocation is also considered. Our numerical and simulation results prove that the implementation of multiple antennas helps boost the energy harvesting capability. Therefore, this paper puts forward a new way to the energy efficiency (EE) enhancement, which contributes to better system performance.