• 대한금속재료학회지
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• 제46권4호
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• pp.189-198
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• 2008

The changes in microstructure and mechanical properties of AZ31 alloy subjected hot-rolling process were investigated. The AZ31 plates fabricated by horizontal continuous casting process were prepared and have hot-rolled from 30 mm to 1 mm in thickness under different processing conditions. At the rolling temperature of $400^{\circ}C$, little surface and side crack was observed up to 20% reduction rate. As total reduction and reduction rate increase to more than 75% and 20% pass, respectively, Grains were more uniformly refined through overall thickness, and particularly lots of shear bands were appeared to be inclined at less than $20^{\circ}C$ along the rolling direction. Average grain size of less than $5{\mu}m$ and tensile properties of YS ${\geq}$ 250 MPa, UTS ${\geq}$ 300 MPa and El. ${\geq}$ 13% were acquired for hot-rolled AZ31 sheets without post-heat treatment. Maximum intensity of (0002) pole figure was decreased with an increase in reduction rate, indicating the improvement of texture by means of high reduction rate.

• 한국분말재료학회지
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• 제30권5호
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• pp.387-393
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• 2023

Transition metal chalcogenides are promising cathode materials for next-generation battery systems, particularly sodium-ion batteries. Ni₃Co₆S₈-pitch-derived carbon composite microspheres with a yolk-shell structure (Ni₃Co₆S₈@C-YS) were synthesized through a three-step process: spray pyrolysis, pitch coating, and post-heat treatment process. Ni₃Co₆S₈@C-YS exhibited an impressive reversible capacity of 525.2 mA h g^-1 at a current density of 0.5 A g^-1 over 50 cycles when employed as an anode material for sodium-ion batteries. However, Ni₃Co₆S₈ yolk shell nanopowder (Ni₃Co₆S₈-YS) without pitch-derived carbon demonstrated a continuous decrease in capacity during charging and discharging. The superior sodium-ion storage properties of Ni₃Co₆S₈@C-YS were attributed to the pitch-derived carbon, which effectively adjusted the size and distribution of nanocrystals. The carbon-coated yolk-shell microspheres proposed here hold potential for various metal chalcogenide compounds and can be applied to various fields, including the energy storage field.

• 한국분말재료학회지
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• 제31권2호
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• pp.152-162
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• 2024

The directed energy deposited (DED) alloys show higher hardness values than the welded alloys due to the finer microstructure following the high cooling rate. However, defects such as microcracks, pores, and the residual stress are remained within the DED alloy. These defects deteriorate the wear behavior so post-processing such as heat treatment and hot isostatic pressing (HIP) are applied to DED alloys to reduce the defects. HIP was chosen in this study because the high pressure and temperature uniformly reduced the defects. The HIP is processed at 1150℃ under 100 MPa for 4 hours. After HIP, microcracks are disappeared and porosity is reduced by 86.9%. Carbides are spherodized due to the interdiffusion of Cr and C between the dendrite and interdendrite region. After HIP, the nanohardness (GPa) of carbides increased from 11.1 to 12, and the Co matrix decreased from 8.8 to 7.9. Vickers hardness (HV) decreased by 18.9 % after HIP. The dislocation density (10^-2/m²) decreased from 7.34 to 0.34 and the residual stress (MPa) changed from tensile 79 to a compressive -246 by HIP. This study indicates that HIP is effective in reducing defects, and the HIP DED Stellite 6 exhibits a higher HV than welded Stellite 6.

• Asian-Australasian Journal of Animal Sciences
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• 제18권6호
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• pp.802-806
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• 2005

The objective of this study was to determine the effects of processing method and rapeseed variety on ruminal and intestinal protein digestibility of rapeseed meal in steers. Intestinal amino acid digestibility was assessed with an in situ ruminal incubation and precision-fed rooster bioassay. In this experiment one traditional rapeseed meal sample (sample A, prepress extraction) and three double low rapeseed meal samples (sample B, prepress extraction, sample C, screw press and sample D, low temperature press) were placed in polyester bags(8 cm${\times}$12 cm) and suspended in the ventral rumen of steers for 16 h. The residues of in situ incubations were intubated to roosters. Total excreta were collected for 48 h after incubation and then desiccated and amino acid concentrations were determined. Results showed that in ruminal incubation the degradation rate of amino acid and crude protein was higher for traditional rapeseed meal sample A than for double low rapeseed meal sample B, but was much lower than for double low sample C and D. In the group of double low rapeseed meal samples, sample D processed by low temperature press had the highest degradation rate of amino acids in the rumen. For all amino acids, the digestibility of the residual protein as measured by the precision-fed rooster bioassay tended to be lower for sample B than for sample A, which had the same processing method with sample B, and in the group of double low rapeseed meals, sample B had similar digestibility of amino acid in residual protein to sample D and higher than that of sample C. However, although the total amino acid availability involving the digestibility of amino acids in the rumen and rooster bioassay of double low rapeseed meal sample D (low temperature press) was higher than those of the other three samples by 7 to 9 percent, there were no significant differences. Results indicated that processing method markedly affected ruminal and post ruminal amino acid digestibility of rapeseed meal when the temperature exceeded 110$^{\circ}C$. Rapeseed meal that had a high content of fiber was not suitable for dry heat treatment at higher temperatures or the amino acids digestibility in rumen and total availability of amino acids could be reduced. Results also suggested the variety of rapeseed meal had no significant effect on the digestibility and availability of amino acids.

• 한국재료학회지
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• 제9권8호
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• pp.837-842
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• 1999

Ta/TaN 다층피막구조는 경도는 떨어지지만 연성이 큰 Ta 막과 취성을 가지며 경도가 높은 TaN 막을 교대로 반복하여 만든 다층구조로서 경도와 연성의 장점이 잘 조화되어 높은 인성을 나타낼 것으로 기대된다. 본 연구에서는 고속도강 기판위에 Ta/TaN 복합다층피막과 compositional gradient Ta-TaN 막을 각각 반응성 스퍼터링에 의하여 증착하고 열처리에 따른 경도 및 접착성을 조사하였다. $N_2$/Ar 유량비가 0.4일 때 결정성이 가장 우수한 TaN 막이 얻어지며, Ta/TaN 복합다층피막의 경도 및 스크래치 테스트 결과도 가장 우수하였다. 또한 Ta/TaN 복합다층피막 증착후의 어닐링 처리 시 어닐링 온도가 증가할수록 피막의 경도와 접착성이 악화되었으며, compositional modulation wavelength가 감소함에 따라 Ta/TaN 복합다층피막의 경도는 증가하지만 접착성은 wavelength에 대한 의존성이 약하게 나타났다. 그리고 compositional gradient Ta-TaN 막 증착후의 어닐링 처리 시 경도와 스크래치 테스트 값은 각각 20$0^{\circ}C$와 40$0^{\circ}C$에서 최대값을 나타내었다.

• 한국재료학회지
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• 제10권6호
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• pp.437-444
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• 2000

기판온도, 박막조성 및 증착후 열처리 등의 조건에 따른 ${La_{1-x}}{Sr_x}{MnO_{3-{\delta}}}$(0.19$\leq$x$\leq$0.31) 박막의 결절구조와 전기전도 특성을 조사하였다. 스퍼터법을 이용하여 $500^{\circ}C$에서 증착된 박막은 강한 <001> 우선배향성과 유사정방정(pseudo-tetrag-onal, a/c-=0.97) 결정체를 나타냈다. 이러한 박막의 단위포는 산소분위기 내에서 증착후 열처리에 의하여 입장정 결정계로 변하였다. $La_{0.67}Sr_{0.33}MnO_3$ 조성의 주타겟과 $La_{0.3}Sr_{0.7}MnO_3$조성의 보조타겟을 동시에 이용하여 박막의 조성을 조절하였다. 보조타겟의 개수에 따라 박막내의 Sr 함량(x)은 0.19-0.31 범위의 값을 나타내었으며, x값이 0.19로부터 0.31로 증가시 금소-반도체의 전이 온도가 상승하였고, 전지비저항이 대체로 감소하였다. 0.18 T의 자기장 하에서, $La_{0.69}Sr_{0.31}MnO_3$조성의 박막의 자기저항변화 MR((%) = (${\rho}_o-{\rho}_H/{\rho}_H$)는 약 390% 이었다.

• 원예과학기술지
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• 제33권6호
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• pp.923-931
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• 2015

본 연구는 일시적인 고온 스트레스 처리가 복색 장미 'Pinky Girl'의 화아 착색과 안토시아닌 생합성 관련 유전자들의 발현 양상에 미치는 영향을 알아보고자 수행되었다. 꽃잎에서 cyanin의 축적은 화아의 발육단계와 연관이 있으며 화아 발육 과정에서 꽃잎이 출현하는 4단계($S_4$)에서 급격하게 일어났다. 따라서 $S_4$ 단계가 꽃잎 착색에 가장 민감한 시기로 판단된다. $S_4$ 단계에서 3일간 고온 스트레스($39/18^{\circ}C$)를 받은 고온처리구에서 개화 당시 꽃잎의 cyanin 착색이 대조구와 비교하여 45.5% 감소하였다. 한편, 안토시아닌 생합성 관련 유전자인 CHS, CHI, F3'H, DFR, ANS, 3GT, 5GT의 발현은 고온처리구에서 오히려 촉진되었다. 예외적으로 F3H의 발현은 고온처리구에서 26.7% 감소하여 'Pinky Girl'의 복색 발현에 의미 있는 유전자로 확인되었다. 하지만 대부분 안토시아닌 생합성 관련 유전자들의 발현은 꽃잎에서의 cyanin 착색 경향과 비례적이지 않았다. 따라서 장미 꽃잎의 화색소 축적은 번역 이후 효과와 조절유전자와 같은 안토시아닌 생합성과 관련된 다른 복잡한 메커니즘이 연관되어 있을 것으로 판단되었다.

• 대한한방내과학회지
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• 제26권2호
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• pp.353-359
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• 2005

Objectives: Dysphagia is a common in stroke patients. Dysphagia often affects the rehabilitation of stroke patients by increasing the risk of nutritional deficits and aspiration pneumonia. Despite the proliferation of physical therapies including swallowing training, much controversy remains regarding the application and benefit of them. Therefore, in this study, the clinical effect of moxibustion at Chonjung(CV17, Shanzhong) on post-stroke dysphagia were assessed using Swallowing Provocation Test(SPT). Methods: Dysphagia subjects were selected by Dysphagia Screening Test. Swallowing function was tested by Swallowing Provocation Test(sec). Direct moxibustion was applied to the acupoint, Chonjung, five times and Swallowing Provocation Test was performed before and after 30 minute. The Latency Time of Swallowing Reflex (LTSR) was checked by SPT. To find factors related with improving swallowing function, Cold-Heat and Excess-Deficiency Diagnosis were considered. Results: A total of 42 patient were included, but two of them were excluded due to severe coughing. Overall, the swallowing reflex improved significantly. In subgroup analysis on brain lesion, non-brain stem lesion patients significantly improved. Moxibustion was more effective in the cold group than in the heat group, but there were no differences between the Excess and the Deficiency groups. Conclusions: The result of this clinical study suggest that moxibustion at Chonjung(CV17, Shanzhong) is an effective treatment for the dysphagia patients after stroke, especially in non-brain stem lesion and the cold diagnosed patients.

• 한국진공학회지
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• 제17권1호
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• pp.23-27
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• 2008

본 연구에서는 상온에서 RF 마그네트론 스퍼터링 법으로 유리 기판위에 증착된 Ga 도핑 된 다결정 ZnO 박막의 특성을 개선하기 위하여 적정 열처리 조건을 분석하였다. 먼저 박막 성장 후 박막의 특성을 분석하였고 각각 $400{\sim}600^{\circ}C$에서 30분, 60분간 질소 분위기에서 열처리를 한 후 구조적, 광학적 특성을 평가하였다. XRD와 FE-SEM을 사용하여 열처리온도 변화에 따른 결정입자의 크기의 변화를 관찰하였다. 그 결과 성장된 결정의 크기의 증가와 박막의 결정성이 향상되었음을 확인할 수 있었으며 그로 인해 박막 특성을 중시하는 투명 전도막의 투과도의 향상 또한 확인할 수 있었다. 결론적으로, 본 실험을 통하여 ZnO 성장 후 적절한 열처리를 수행함으로서 GZO 박막을 사용하여 제작된 소자의 특성을 개선할 수 있으리라 판단된다.

• 생명과학회지
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• 제20권11호
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• pp.1634-1639
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• 2010

본 연구는 무지개송어 양식 산업의 생산성 향상을 위해 전 암컷 무지개송어 대량생산을 위한 일환으로 성호르몬에 의한 생리학적 성전환과 자성발생 2배체어를 유도하였다. 생리학적으로 성전환된 수컷을 만들기 위하여 부화 후 첫 먹이를 먹는 시기에 웅성호르몬인 17 alpha-methyltestosterone (MT) 5 mg을 사료에 흡착시켜 사육수온 $13^{\circ}C$에서 적산수온 $800^{\circ}C$까지 처리한 결과 96.7%의 수컷 유도율을 보였다. 또한 정상 수컷 정액을 이용하여 수정 10분 후 $28^{\circ}C$에서 20분간 고온 처리하여 61.7%의 자성발생 2배체가 유도되었다.