• 한국분말재료학회지
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• 제29권5호
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• pp.418-423
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• 2022

Carbon fibers (CFs) are considered promising composite materials for various applications. However, the high cost of CFs (as much as $26 per kg) limits their practical use in the automobile and energy industries. In this study, we developed a continuous stabilization process for manufacturing low-cost CFs. We employed a textile-grade polyacrylonitrile (PAN) fiber as a low-cost precursor and UV irradiation technique to shorten the thermal stabilization time. We confirmed that UV irradiation on the textile-grade PAN fibers could lower the initial thermal stabilization temperature and also lead to a higher reaction. These resulted in a shorter overall stabilization time and enhancement of the tensile properties of textile-grade PAN-based CFs. Our study found that only 70 min of stabilization time with UV irradiation was required to prepare textile-grade PAN-based low-cost CFs with a tensile strength of 2.37 ± 0.22 GPa and tensile modulus of 249 ± 5 GPa.

• Preventive Nutrition and Food Science
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• 제8권2호
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• pp.185-190
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• 2003

Gamma irradiation was used as part of a new processing method to produce a brighter-colored and mild-flavored green tea leaf extract that retained all of its physiological activities. Dried green tea leaf was extracted with 70% ethanol and gamma irradiated at 0,5, 10, 20 kGy. Hunter color $L^{*}$- and $a^{*}$-values were increased with irradiation in a dose-dependent manner, which was a color range from dark brown to bright yellow. However, the irradiation effect gradually disappeared during 3 weeks of storage, with color reverting to that of untreated samples. There was no difference in the radical scavenging and tyrosinase inhibition effect by irradiation. Among antioxidants used, ascorbic acid was the most effective against color reversion. In contrast, cysteine was shown to protect the effect of color change with irradiation. Results indicated that enhanced color of irradiated green tea leaf extract can be effectively controlled by additives such as ascorbic acid and a low storage temperature.e.e.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2011년도 제45차 학술발표회
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• pp.7-7
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• 2011

Poly(ethylene terephthalate)(PET) is one of the most widely used materials in textile industry. It can have a low cost, silk-like handle, and excellent mechanical properties. Low thermal stability of PET had been a common problem limiting its high temperature application. The polyester have been known to have the disadvantage of degradation under ionized irradiation compared to crosslikable polymers such as polyethylene, polypropylene and polystylene. To improve thermal stability of PET, the PET films were photocrosslinked by UV irradiation. A hydrogen-abstractable photoinitiator was used to photocrosslink of PET by continuous UV irradiation. Photoinitiator addition increased the gel fraction. The photocrosslinking was attributed to the recombination of PET radicals generated upon UV irradiation, which was enhanced by the hydrogen abstraction of the PET polymer chains by the added photoinitiator. Also the crosslinked PET showed higher thermal stability and mechanical strength with increasing UV energy. Polyester type films such as poly(ethylene naphthalate)(PEN) and poly(butylene terephthalte)(PBT) were also increased the gel fraction and improved thermal stability and mechanical properties by UV irradiation.

• 한국식품영양과학회지
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• 제40권9호
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• pp.1307-1313
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• 2011

방사선 조사 기술을 이용한 타락죽의 멸균 시 관능적 품질을 개선하기 위한 연구의 일환으로 방사선 조사온도에 따른 타락죽의 pH, 지질산패도, 점도, 색도, 관능검사 및 향기패턴을 측정하였다. 그 결과 pH와 색도의 경우 방사선 조사에 의한 변화는 없는 것으로 나타났다. 지질산패도의 경우 조사구 가운데 냉동조사구가 가장 낮았으나, 점도에서는 냉동조사구가 가장 높게 나타났다. 관능검사 결과, 종합적 기호도에서 냉동조사구의 경우 대조구와 유의적 차이가 없는 것으로 나타났다. 향기패턴 분석 결과, 지질산패 및 이취에 관련된 RT 3.88 sec의 peak와 타락죽 고유의 향과 관련한 RT 7.34 sec의 peak를 구분할 수 있었다. 따라서 방사선을 조사에 의한 타락죽의 관능적 품질 저하는 냉동조사를 통해 개선이 가능하였으나, 여전, 지질산패와 점도감소 및 조사취 발생 등에 의한 타락죽 고유의 관능적 품질이 감소되는 것으로 나타나, 추후 항산화제의 첨가 또는 포장방법의 변화 등과 병용처리를 통해 보다 효과적인 품질 개선을 위한 연구가 필요할 것으로 사료되었다.

• 한국초전도ㆍ저온공학회논문지
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• 제21권3호
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• pp.13-17
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• 2019

We investigate the effect of thermal annealing on $MgB_2$ thin films with thicknesses of 400 and 800 nm, irradiated by 350 keV C-ions with a dose of $1{\times}10^{15}atoms/cm^2$. Irradiation by low-energy C-ions produces atomic lattice displacement in $MgB_2$ thin films, improving magnetic field performance of critical current density ($J_c$) while reducing the superconducting transition temperature ($T_c$). Interestingly, the lattice displacement and the $T_c$ are gradually restored to the original values with increasing thermal annealing temperature. In addition, the magnetic field dependence of $J_c$ also returns to that of the pristine state together with the restoration of $T_c$. Because $J_c$(H) is sensitive to the type and density of the disorder, i.e. vortex pinning, the recovery of $J_c$(H) in irradiated $MgB_2$ thin films by thermal annealing indicates that low-energy C-ion irradiation on $MgB_2$ thin films primarily causes lattice displacement. These results provide new insights into the application of low-energy irradiation in strategically engineering critical properties of superconductors.

• 한국전기전자재료학회논문지
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• 제26권9호
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• pp.677-681
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• 2013

Apart from the deposition of alignment layer, alignment process needs to be involved for alignment of liquid crystal (LC) molecules. To simplify manufacturing process, several method were used such as rubbing, ion-beam irradiation, UV irradiation, and lithography. But, eventually it needs another treatment for LC alignment. Here, we suggested Si induced polyimide (PI) alignment layer at low temperature. Using this method, we are able to eliminate the alignment process and found that the alignment and electro-optic performance are much better than that of the rubbed PI LC cells. Compared to the rubbed PI cells, the response time was decreased by 70% and C-V characteristics have hysteresis-free.

• 천문학회보
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• 제46권1호
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• pp.50.1-50.1
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• 2021

Gravitational instability (GI) can produce massive gas giants on wide orbits by fragmentation of protoplanetary disks (PPDs). While most previous works focus on PPDs around solar mass stars, gas giants have been observed in systems with a wide range of stellar masses including M dwarfs. We use the GIZMO code to perform global three-dimensional simulations of self-gravitating disks around low-mass stars. Our models consider heating by turbulent viscosity and stellar irradiation and the β cooling occurring over the dynamical time. We run various models with differing disk-to-star mass ratio q and disk temperature. We find that strongly gravitating disks either produce spirals or undergo fragmentation. The minimum q value for fragmentation is 0.2-0.7, with a smaller value corresponding to a more massive star and/or a smaller disk. The critical q value depends somewhat sensitively on the disk temperature, suggesting that the stellar irradiation is an important factor in determining GI. We discuss our results in comparison with previous work as well as recent ALMA observations.

• 한국표면공학회지
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• 제29권6호
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• pp.773-780
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• 1996

Silicon oxide films were prepared by using five kinds of organosilicon compound as gas sources without oxygen by rf plasma-enhanced CVD (PECVD). UV light was irradiated on a substrate vertically during deposition to enhance film oxidation and ablation of carbon contamination in a deposited films. Films prepared with UV irradiation contained less carbon than those prepared without UV irradiation. The oxidation of the films was improved by UN irradiation. The effect of UV irradiation was, however, not observed when the films were prepared with tetramethy lsilane (TMS) which contained no oxygen atom. Dissociated oxygen atoms from an organosilicon compound were excited in the plasma with UV irradiation around the substrate surface and affected the enhancement of film oxidation and ablation of carbon in the films.

• 한국전기전자재료학회논문지
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• 제21권5호
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• pp.486-491
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• 2008

The plasma processing is applied to many industrial fields as thin film deposition or surface treatment technique. In this study, we investigated large-area uniformed surface treatment of PET film at low temperature by using Scanning Plasma Method(SPM). Then, we measured difference and distribution of temperature on film's surface by setting up a thermometer. We studied the condition of plasma for surface treatment by examining intensity of irradiation of uniformed plasma. And we compared contact angles of treated PET film by using Ar and $O_2$ plasma based low temperature. In our result, surface temperature of 3-point of treating is low temperature about $22^{\circ}C$, in other hands, there is scarcely any variation of temperature on film's surface. And by using Ar plasma treatment, contact angle is lower than untreatment or $O_2$ plasma treatment. In case of PET film having thermal weak point, low temperature processing using SPM is undamaged method in film's surface and uniformly treated film's surface. As a result, Ar plasma surface treatment using SPM is suitable surface treatment method of PET film.

• 한국식품영양과학회지
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• 제11권4호
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• pp.53-59
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• 1982

감자의 장기안전저장법(長期安全貯藏法) 개발(開發)을 위하여 적정조사선량(適正照射線量)및 적정조사시기(適正照射時期)를 구명(究明)한 결과(結果)는 아래와 같다. (1) 품종간(品種間)에 차이(差異)는 있으나 수확후 $15{\sim}30$일(日) 사이에 방사선(放射線)을 조사(照射)할때는 12.5krad의 선량(線量)이 적당하고, 수확후 45일(日) 이후에 조사(照射)할때는 15krad 정도의 조사(照射)가 필요(必要)하며, 가급적 수확후 휴면기간(休眠期間)중 빨리 조사(照射)하는 것이 유리하다고 본다. (2) 적정조사선량(適正照射線量)에서의 조사구(調査區)는 무처리구(無處理區)에 비(比)해 물리적성질(物理的性質)이 우수(優秀)하였으며, 방사선조사(放射線照射) 후(後) 자연저온저장고(自然低溫貯藏庫)에 저장(貯藏) 함으로서 무처리구(無處理區)보다 저장기간(貯藏期間)을 4개월이상(個月以上) 연장시킬수 있었다.