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군청안료의 합성에 있어서 반응 메카니즘에 관한 기초적 연구
황선국,유연태,최영윤,홍성웅,Hwang, Seon-Guk,Yu, Yeon-Tae,Choe, Yeong-Yun,Hong, Seong-Ung 한국재료학회 1997 한국재료학회지 Vol.7 No.10
본 연구에서는 고령토, 유황, 탄산나트륨, 규석 및 송진을 원료로 하여 군청을 합성하였고, 그 반응 메카니즘을 조사하였다. 원료의 혼합시료는 군청의 중간 생성물인 녹색군청을 합성하기 위하여, 82$0^{\circ}C$에서 4시간 동안 소성하였다(승온율 2$^{\circ}C$/min). 합성된 녹색군청은 최종적으로 군청을 얻기 위해 50$0^{\circ}C$에서 산화처리하였다. 합성 과정에서 발생하는 반응 생성물 및 이들의 구조적 변화는 x선 회절 분석과 Raman Spectrum 분석에 의하여 평가하였다. 소성과정에서 황화나트륨은 50$0^{\circ}C$에서 생성되었고, NaAISiO$_{4}$는 62$0^{\circ}C$에서 형성되었다. 그리고, 녹색군청은 황화나트륨과 NaAISiO$_{4}$의 반응에 의하여 74$0^{\circ}C$부근에서 형성하기 시작하였다. 또한, 청색군청의 형성은 녹색군청 중에 잔존하던 황화타트륨의 산화로 방출되는 유황 원자에 기인하였다.
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분만계절이 TMR 급여 홀스타인 육성우의 분만 후유생산과 비유지속성에 미치는 영향
김연정,황선국,남인식,안종호 한국유기농업학회 2019 韓國有機農業學會誌 Vol.27 No.3
Total of 20 Holstein calves of 10 calves (3.90±0.26 month of age) born in spring (S) and 10 calves (4.10±0.30 month of age) born in fall (F) were reared in this study for 24 months and diets were divided into separate feeding of forage and concentrates (C) and TMR (T). Therefore, 4 treatments in this study were composed of CS, CF, TS and TF with the factors of diets and calving season. After parturition of heifers, all animals were fed the same diet and milk production was recorded monthly. DM intakes in growing period were influenced by calving season, and those of the animals calved in fall were higher than in those calved in spring (P<0.01), but there were no significant differences by feeding method. CP intakes and TDN intakes were significantly influenced by calving season (P<0.05) and feeding method (P<0.001), and the animals calved in fall were about 1.2% higher than those calved in spring, and the animals fed TMR were about 4.7% higher than those fed concentrates and forage separately. Average, 9th and 10th months' milk yields were significantly influenced by feeding method in which those in the treatments fed TMR (TS, TF) were higher than in separate feeding of concentrates and forage (CS, CF; average P<0.05; 9th and 10th months P<0.01). Average milk persistency was also significantly influenced by calving season (P<0.05) and feeding method (P<0.01) and those in the animals calved in fall were higher than in spring and those of the TMR fed animals were also higher than in separate feeding of concentrates and forage. Milk persistency was similar to the results of milk yield, showing statistically significant differences affected by the feeding method at 9th and 10th months of late lactation (P<0.01), and it was about 8% higher in the animals fed TMR, showing higher tendency at 7th (P=0.12) and 8th months of late lactation (P=0.09). Therefore, it is expected that postpartum milk yield and milk persistency would be higher when the hiefers are fed TMR in growing period and calved in fall. Average milk fat content was influenced by feeding method. Milk fat content of the animals fed TMR during growing period were 7.8% higher than those fed concentrates and forage separately (P<0.01). This suggests that feeding TMR during growing period influenced first postpartum eating behavior, which stabilized the rumen and resulted in the increased milk fat. At 3rd month after calving, milk fat content was lower in the animals calved in spring than in those calved in fall, suggesting that it might have been influenced by the seasonal differences. MUN showed significant differences by feeding method in which those in separate feeding of concentrates and forages were higher especially in average, 4th, 5th and 6th months (average and 4th P<0.01; 5th and 6th months P<0.05). SCC was higher in the animals fed TMR than in those fed concentrates and forage separately especially in average, 3rd and 4th months after calving (P<0.01). In conclusion, when feeding TMR during growing period and calving in fall, it was not influenced by the high temperature in summer, and it resulted in the improved milk yield, milk persistency and milk fat content.
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홍천지구 저품위 철광에 대한 선광시험 : 홍천철광 Hongchon Mine
조명승,정인복,황선국,고원식 대한금속재료학회(대한금속학회) 1968 대한금속·재료학회지 Vol.6 No.2
Mining Research Center is making a study to establish and develop a practical ore-dressing procedure with low grade iron ore in Hongchon area and the Report 1, Jaun iron mine, issued on October 20th, 1967. Now, Government is planning to exploit the relatively high grade iron ore as selective mining at Hongchon mine which is estimated about 3,200,000 ton containing around 32% Fe prior to regular mine exploitation in this area. Hereby, a beneficiation study was mainly carried out with the composite sample taken from 4 outcrops at Hongchon mine which consisted mostly with magnetite and some pyrite, 38.7% Fe (39.3% of total Fe), 1.1% S, 0.75% P, 2.9% Mn and etc. Through various studies, magnetite concentrate could be successfully yielded up to 60 % Fe concentrate containing 0.22% S and 0.20% P with about 82 % of recovery by wet magnetic separation to grind minus 28 mesh, pyrite flotation concentrate containing up to 40% S with about 65% of recovery to regrind to minus 65 mesh using 200 g/t of copper sulfate, 60 g/t of Z-6, 48 g/t of pine oil and at pH 7 to 7.5.
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커플링 급전을 이용한 모바일용 다중대역 안테나에 관한 연구
왕정,윤인섭,황선국,염효가,박효달,WANG, Cheng,YOON, In-seop,HWANG, Sun-gook,YAN, Xiao-jia,PARK, Hyo-Dal 한국정보전자통신기술학회 2014 한국정보전자통신기술학회논문지 Vol.7 No.4
본 논문은 LTE (0.746 ~ 0.798 GHz), GSM(0.824 ~ 0.960 GHz), DCS(1.71 ~ 1.88 GHz), WCDMA(1.91 ~ 2.17 GHz) 대역에서 사용 가능한 다중 대역 모바일 안테나에 대하여 제안하였다. 제안된 안테나는 기본적인 PIFA 구조에 두 개의 브랜치 라인을 추가하여 다중대역을 형성하고, 커플링 급전 방식을 사용하여 대역폭을 향상시킨 안테나이다. 안테나의 크기는 $122mm{\times}50mm{\times}0.8mm$이며, FR4(${\epsilon}_r=4.4$)를 사용하였으며, 측정결과 VSWR < 2(${\leq}-10dB$)을 기준으로 모든 주파수 대역을 만족하였다. 제안된 다중대역 안테나는 낮은 주파수대역에서 0.93 ~ 1.92 dBi의 이득과 49.60 ~ 76.35 %의 방사효율 특성을 보이고, 높은 주파수대역에서는 2.19 ~ 4.66 dBi의 이득과 60.40 ~ 80.01 %의 방사효율 특성을 보였다. 따라서 본 논문에서 제안한 다중대역 안테나는 현재 상용화 되어있는 이동통신 단말기용 안테나에 비해 전 대역에서 우수한 특성을 확인하였다. 이와 같은 우수한 특성으로 인하여 본 연구에서 제안된 안테나는 4세대 모바일 단말기뿐만 아니라 향후 개발하고 있는 B4G용 안테나로 적용 가능 할 것으로 판단된다. In this paper, an antenna which has quad band in LTE (0.746 ~ 0.798 GHz), GSM(0.824 ~ 0.960 GHz), DCS(1.71 ~ 1.88 GHz), WCDMA(1.91 ~ 2.17 GHz) is proposed. An antenna size is $122mm{\times}50mm{\times}0.8mm$ on FR4(${\epsilon}_r=4.4$) ground substrate. In the proposed antenna, branch line is applied to the conventional PIFA architecture to achieve multi-bandwidth. Coupling power supply is applied for a wide bandwidth. Result of the measurement is as follows. When the low frequency, the antenna presents gain of 0.93 ~ 1.92dBi, and radiation efficiency of 49.60 ~ 76.35 %, and When the high frequency, gain is 2.19 ~ 4.66dBi, and radiation efficiency is 60.40 ~ 80.01 %, and with a VSWR < 2 (${\leq}-10dB$)measurement results for standard satisfies all band. Judging from the result, proposed multiband antenna is expected to be applied. B4G mobile terminals since the antenna shows an outstanding performance.
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