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내부 확산법에 의한 Nb$_3Sn$ 초전도 선재에서 부분 가열이 초전도 특성에 미치는 영향
하동우,오상수,하홍수,이남진,권영길,류강식,Ha, Dong-Woo,Oh, Sang-Soo,Ha, Hong-Soo,Lee, Nam-Jin,Kwon, Young-Kil,Ryu, Kang-Sik 한국초전도저온공학회 2000 한국초전도저온공학회논문지 Vol.2 No.2
There is the possibility that internal tin processed Nb$_3Sn$ wires are locally heated during the drawing process and the jacketing process. It is important to know the variations in J$_c$ of internal tin processed Nb$_3Sn$ wires caused by local heating. Internal tin processed Nb$_3Sn$ rods were cold worked to 2.28 mm, using the appropriate reduction ratio, and then cut into several pieces. At this stage, wires were locally 50 mm heat zone heated up to 360$^{\circ}C$. The locally heated Nb$_3Sn$ wires were drawn to a final diameter size of 0.81 mm. Others were cold worked successively to 0.81 mm and locally heated with the same conditions. 2 types of locally heat treated wires were wound on Ti-6Al-4V barrels and heat treated for the Nb$_3Sn$ reaction. Local heating of internal tin processed Nb$_3Sn$ wires after the J$_c$ of these wires. However, local heating at an intermediate stage of the drawing process caused a decrease in J$_c$. When the local heating temperatures were higher than melting point of Sn, non-Cu J$_c$'s decreased significantly. A Sn-Cu alloyed boundary appeared after local heating over the melting point of Sn, and caused work hardening and a decrease in the workability.
하동우 ( Dong Woo Ha ),김광하 ( Gwang Ha Kim ),김동욱 ( Dong Uk Kim ),배민정 ( Min Jung Bae ),김보원 ( Bo Won Kim ),전혜경 ( Hye Kyung Jeon ),박도윤 ( Do Yun Park ),서형일 ( Hyung Il Seo ) 대한소화기학회 2011 대한소화기학회지 Vol.58 No.3
Neuroendocrine tumors are usually found in the ileum, appendix, rectum, colon and stomach. Ampullary neuroendocrine tumor is extremely rare and only a few cases of neuroendocrine carcinoma of the minor papilla have been reported. The preoperative diagnosis is very challenging because either asymptomatic or manifests as nonspecific abdominal pain. The tumor is relatively small and located at the deep mucosa and submucosa. Endoscopy with deep biopsy, endoscopic retrograde cholangiopancreatography and endoscopic ultrasonography are good diagnostic tools. The best therapeutic choice is surgery. We report an unusual case of a 55-year-old woman who underwent endoscopy as part of a regular health checkup and was diagnosed a neuroendocrine carcinoma in the minor papilla, which was successfully resected by pancreaticoduodenectomy. (Korean J Gastroenterol 2011;58: 144-148)
하동우(Ha, Dong-woo),고락길(Ko, rock-kil) 대한전기학회 2022 전기의 세계 Vol.71 No.1
트럭과 같은 부하가 큰 상용차에서는 에너지의 밀도가 높고 가벼운 액체 수소를 연료로 사용하려는 연구가 활발하게 진행하고 있다. 본 기사에서는 한국전기연구원에서 개발 중인 액체 수소로 초전도 코일을 냉각시키고 연료 전지를 초전도 코일의 전원으로 사용하는 기술을 소개한다. 이 기술은 향후 작고 가벼우면서도 강력한 파워팩 또는 추진 장치를 개발하는 데 사용될 것이다. In a commercial vehicle with a heavy load, such as a truck, research to use liquid hydrogen, which has high energy density and is light, as a fuel is being actively conducted. This article introduces a technology that cools a superconducting coil with liquid hydrogen and uses a fuel cell as a power source for the superconducting coil, which is being developed by KERI. This technology will be used in the future to develop small, light yet powerful power packs or propulsion devices.
PRESENT AND FUTURE DEVELOPMENTS OF PORTS IN ASIA THE PACIFIC
하동우(Dong-Woo Ha) 한국항만경제학회 2002 韓國港灣經濟學會誌 Vol.18 No.2
The continuing pace of technological change and the trend toward larger and faster ships is evident as shipping lines compete in seeking economies of scale in the global market and ports become increasingly reliant on sophisticated equipment. Across the Asia and Pacific region some of the worlds most modern container ships are calling at an extensive network of mainline and feeder ports. <br/> This paper shows that during the period from 1999 to 2011, Asian container trade is expected to continue to increase more rapidly than the world average, i.e., 7.2 per cent per annum compared with the world average of 6.3 per cent. It is forecast that the total volumes of international containers handled at the ports in Asia and the Pacific will increase at an average growth rate of 7.2 per cent per annum.<br/> In order to handle the anticipated port container traffic in 2011, new container berths are required in nearly every country in the Asia and the Pacific region. This will entail very significant capital investment requirements.<br/> If countries in the UNESCAP region are to position their ports to meet the challenges of the next decade, there is an urgent need to implement more robust strategies to address important issues including prioritisation of port development projects, promotion of private sector participation in ports, emphasis on productivity and preparation for intermodal integration and logistics growth.
액체 수소를 활용한 극저온 부품의 냉각 과정에서 발생하는 BOG에 관한 이론적 연구
하동우(DONG WOO HA),노현우(HYUN WOO NOH),서영민(YOUNG MIN SEO),구태형(TAE HYUNG KOO),고락길(ROCK KIL KO) 한국수소및신에너지학회 2023 한국수소 및 신에너지학회논문집 Vol.34 No.6
In this study, the theoretical analysis focused on the quantity of liquid hydrogen required for cooling down to 20 K, as well as the generation of boil-off gas (BOG) from the cooling process of the cryogenic components. The study involved calculating the amount of liquid hydrogen needed to achieve the desired temperature for the cryogenic components and subsequently determining the resulting BOG production at various reference temperatures. It was shown that it was important to efficiently lower the temperature of cryogenic parts through preliminary cooling. As a result, the reference temperature and pressure had an influence on the BOG generation on the cooling of cryogenic components using liquid hydrogen.
박치완,장건익,하동우,성태현,Park, Chi-Wan,Jang, Gun-Eik,Ha, Dong-Woo,Seung, Tae-Hyun 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.5
High-temperature Superconductor(HTS) tubes were fabricated in term of different processing variables such as preheating temperature, speed of mold rotation and cooling rate by centrigugal forming method. For powder melting by induction the optimum range of melting temperatures and preheating temperature were $1050{\circ}C{\sim}1100{\circ}C\;and\;550{\circ}C\;for\;30\; min$, respectively The mould roating speed was 1000 rpm. A tube was annealed at $840 {\circ}C$ for 72 hours in oxygen atmosphere. The plate-like grains were well developed along the loafing direction and typical grain size was about more than $40{\mu}$. It was found that Ic values increased with increasing the Preheating temperature and speed of mold rotation. While Ic decreased with increasing the cooling rate. The measured Ic in $50mm{\times}70mm{\times}2.5mm$ tube was about 896 Amp.
임성우,고상기,하동우,오상훈,장인화,Im, Sung Woo,Ko, Sang Ki,Ha, Dong Woo,Oh, Sang Hoon,Chang, In Hwa 한국강구조학회 2000 韓國鋼構造學會 論文集 Vol.12 No.6
In this study, the chemical compositions and mechanical properties of high tensile strength steel plates in accordance with their thickness are quantitatively estimated, that are steel plates SM570 to be purposed to use in building structure. Test results of steel plates SM570 are compared with those of steel plates SS400 and steel plates SM490 mostly using building structure. It is found that chemical compositions, carbon equivalent, parameter of welding crack susceptibility, yield strength, tensile strength, elongation, and impact strength have satisfied the prescribed value in KS code for all case of thickness. 본 연구에서는 고장력 용접구조용 압연강재인 SM570을 건축구조용으로 사용하기 위해서 판두께에 따른 화학성분과 기계적 성질의 분포특성을 정량적으로 평가하였다. 또한 건축구조용 강재로 주로 사용되는 일반구조용 압연강재인 SS400과 용접구조용 압연강재인 SM490을 비교재로 사용해서 SM570 강재와 비교 평가하였다. 본 연구결과 모든 두께에서 SM570 강재의 화학성분, 탄소당량, 용접 갈라짐 감수성 조성과 항복강도, 인장강도, 연신률 및 충격강도는 한국산업규격을 만족하였다.