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이선재,정선화,조병선,S.J. Lee,S.H. Jeong,B.S. Cho 한국전자통신연구원 2023 전자통신동향분석 Vol.38 No.4
The competition for technological supremacy is unfolding in the high-tech field, and quantum computing can be determinant for economic and security ripple effects. The United States and China, leaders in quantum computing, have developed this field through adequate policies. The United States has fostered quantum computing through government policies and competition among private companies, while China has secured world-class technology through large-scale government investment and attracting foreign talent. In quantum computing, securing talented people is essential to guarantee independent technology development regarding academic attributes and security. We analyze quantum computing policies in the United States and China on a timeline and determine their policy trends. In addition, the policies for securing talent in these countries are reviewed, and the policy effects are compared based on literature analysis. Through the analysis of policy cases between the United States and China, bilateral policy implications for Korea are delineated.
볼 타입 공구를 이용한 SPIF 공정의 표면 특성 분석
경준현(J. H. Kyeong),윤형원(H. W. Youn),이병협(B. H. Lee),이선재(S. J. Lee),조경훈(K. H. Cho),이창환(C. H. Lee) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
판재점진성형은 정해진 공구 경로에 따라 판재를 성형하는 공법으로 CNC, 로봇 팔과 같은 공작기계로 성형한다. 일반적으로 반구형 금속공구를 사용하는데 소재와의 마찰로 인해 표면에 공구 자국이 남고, 표면이 손상된다. 이때, 3 축 자유도가 있는 볼 공구가 마찰을 최소화할 수 있는 대안이 될 수 있다. 본 연구에서는 볼 타입 공구를 이용한 점진성형공정의 표면 특성 분석을 수행하였다. 3 축 회전 자유도가 있는 Ball Roller 공구를 제작하고, 같은 공구 직경의 반구형 공구와 비교실험을 실시했다. 실험계획은 다음과 같다. CNC 3 축 가공기에서 SPIF 공정으로 진행했으며, 공구이송속도 4,000 mm/min, 공구회전속도 125 RPM 으로 고정하고, 공구 경로는 Coutour 로 하였다. StepDown은 0.1, 0.25, 0.5, 0.75, 1, 1.5, 2 mm 로 설정하였다. 형상은 사각 피라미드로 AA5052 판재를 성형하였다. 성형된 판재를 표면 거칠기 측정기로 성형면의 Ra, Rz 를 측정하여 공구이동간격에 대한 경향을 비교하였다. 측정결과, 볼 타입 공구와 일반 반구형 공구의 공구이동간격에 대한 Ra, Rz 경향은 유사하였다. 그리고 전자주사현미경과 공초점 현미경을 통해 표면 형태를 분석했다. 일반 반구형 공구는 원소재의 표면 흔적이 없고, 공구와의 마찰 면에 선 속도 차이에 의한 표면 상태가 확인되었다. 볼 타입 공구로 성형했을 경우, 소성변형으로 인한 Orange Peel Effect 가 나타났고, 원소재의 표면 상태를 다소 유지시킬 수 있음을 확인했다.
이현원(H.W.Lee),최세경(S.K.CHOI),김명찬(M.C.KIM),이선재(S.J.LEE),이상동(S.D.LEE) 전력전자학회 1999 전력전자학술대회 논문집 Vol.- No.-
The three level circuit systems are able to reduce harmonic currents without requiring high frequency switching to the devices, and are suitable for high voltage, large capacity systems. However the three level circuit system has a problem that the mid point potential varies when the current flows into or out of the mid point. the variation causes voltage deviation in the DC waveforms as well as unbalanced voltage stress to the switching devices therefore the variation should be suppressed.<br/> In this paper we have proposed a new kind of PWM method for three level circuit system based on the change of phase PWM reference value with the ability to suppress the mid point voltage variation. The new method is easily implemented without complicated calculation and it's performance is similar to space vector modulation. The validity of the proposed method is verified by computer simulation
조병선,이선재,정선화,B.S. Cho,S.J. Lee,S.H. Jeong 한국전자통신연구원 2024 전자통신동향분석 Vol.39 No.3
Quantum computing can be a game changer in all areas of economy security, and society, and it is expected to bring innovation to the entire industrial ecosystem. The competition in this industry is accelerating with various countries pushing for policies to preempt technology and maintain a technological advantage. The quantum computing market is expected to show commercial gains in 2027 as an inflection point. Initially, it is expected to replace the high-performance computing market. However the continuous growth of quantum computing will depend on the development innovative services such as ChatGPT in AI, and technological breakthroughs. We examine the definition and outlook, evolution and dynamics, and supply chain structure of the quantum computing industry in an attempt to unveil implications for its development.
사료의 단백질 수준과 첨가제들이 육계사내 암모니아가스 발생에 미치는 영향
백인기,최선우,이선재,남궁환 한국동물자원과학회 2000 한국축산학회지 Vol.42 No.3
Two experiments were conducted to determine the effect of crude protein levels and feed additives on N excretion and ammonia gas emission in broiler house. In Experiment 1, one thousand hatched broiler chickens (Ross^ⓡ) were assigned to 2 X 2 factorially arranged dietary regimen for 5 week feeding trial; two levels of crude protein (21.5% and 18.5%) plus amino acids (AA) and two levels of a Bacillus subtilis base probiotics product, Bio-21^ⓡ(0% and 0.1%). In Experiment 2, eight hundred hatched broiler chickens were assigned to 5 treatments: T1 Control(22% CP for prestarter, 20% CP for stager and 18% CP for grower), T2; Low protein(22% CP for prestarter, 19% CP+AA for starter and 17% CP+AA for grower), T3; T2 + Bio-21^ⓡ(0.1%), T4; T2 + Bio-21^ⓡ(0.1%) + Yucca fermentation product(0.01%), T5; T2 + Bio-21^ⓡ(0.1%) + Yucca fermentation product(0.01%) + CuSO₄· 5H₂O(125 ppm in Cu). Experiment 2 were carried out for 4 week after the first 1 week adaptation to environment during when chicks were fed commercial prestarter diet. In Experiment 1, weight gain and feed intake of chicks fed the diets with normal protein (21.5%) were higher (P$lt;0.05) than those of chicks fed diets with low protein (18.5%+AA). Bio-21 did not affect these parameters. Low protein diet decreased total N, nitrate-N and uric acid-N in feces but Bio-21^ⓡ did not affect them. Ammonia gas emission tended to be decreased in the treatments of low dieatry protein and Bio-21^ⓡ at D 22 and D 28, and the decrease was significant in low protein treatments at D 35. In Experiment 2, the performance of chicks was not affected by treatments. Low protein diet combined with Bio-21^ⓡ, yucca fermentation product and copper sulfate (T5) significantly (P$lt;0.05) decreased total N, nitrate-N and uric acid-N in feces. Ammonia gas emission was not different among treatments for the first 3 weeks but it was decreased (P$lt;0.05) at 4th and 5th wk by low protein and additives supplemented diet. Moisture content and pH of litter tended to be increased in all treatments until 3 week. Results indicated that N excretion and ammonia gas emission can be reduced by low protein diet alone or together with Bio-21^ⓡ and copper sulfate.
식물성 사료원료 내 피틴태 인의 함량과 PHYTASE ACTIVITY 및 그 특성에 관한 연구
엄재상,백인기,이선재,남궁환 한국영양사료학회 1999 韓國營養飼料學會誌 Vol.23 No.6
본 실험은 국내 사료회사들이 사용 중인 식물성 사료원료를 수집하여 phytate-P, total-P 그리고 phytase activity를 측정함으로써 가축이 필요로 하는 P의 적정 첨가량을 결정 할 수 있는 기초자료와 밀 phytase와 미생물 phytase의 pH 및 온도 변화에 따른 activity의 변화를 구명하고자 실시하였다. Phytate-P는 대부분 강피류에 많이 함유되어 있었다. 강피류 중에서도 미강 (1,201 ㎎/100g)과 탈지강 (1,077 ㎎/100g), corn gluten feed (896 ㎎/100g), 밀기울 (742㎎/100g) 그리고 채종박 (535 ㎎/100g)에 많이 함유되어 있었고, 다른 원료의 phytate-P는 500 ㎎/100g 이하였다. Total-P는 탈지강 (1,899 ㎎/100g), 미강 (1,886 ㎎/100g), 채종박 (1,016 ㎎/100g) 등에 많이 함유되어 있었다. Phytase activity는 밀 (1,121.9 U/㎏)과 밀기울 (2,935.1 U/㎏)에서 높은 활성을 보였다. pH와 온도의 변화에 따른 미생물 phytase와 밀 phytase의 activity는 모두 pH 5.5와 50℃를 전후하여 최고치를 나타내었다. 그러나 pH 6과 60℃ 이상에서 급격히 감소하는 경향을 보였다. 밀 phytase 보다는 미생물 phytase가 보다 더 급격히 감소하여 식물성 phytase가 pH와 온도변화에 대해서는 내성이 더 강한 것으로 나타났다. An experiment was conducted to measure the contents of phytate-P, total-P and phytase activity of cereals and cereal by-products. The effects of pH and temperature on the activity of wheat and microbial phytase were compared. Phytate-P content was higher in most cereal by-products than in cereal. Rice bran had the highest phytate-P (1,201 ㎎/100g) followed by defatted rice bran (1,077 ㎎/100g), corn gluten feed (896 ㎎/100g), wheat bran (742 ㎎/100g) and rapseed meal (535 ㎎/100g). The phytate-P contents of other ingredients were lower than 500 ㎎/100g. Total-P content was high in defatted rice bran (1,899 ㎎/100g), rice bran (1,886 ㎎/100g), and rapseed meal (1,016 ㎎/100g) compared to other ingredients. Wheat and wheat bran had the highest phytase activity (1,121.9 and 2,935.1 U/㎏) among ingredients tested. The activity of wheat and microbial phytase was gradually increased until pH and temperature reached at 5.5 and 50℃ respectively, then their activity remarkably decreased at pH 6 and 60℃. Wheat phytase was as stable, if not more, as microbial phytase under different pH and temperature.