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이산화탄소 산화제를 이용한 탄화수소의 촉매 탈수소화 기술
장종산,박민석,정성화,박상언 한국공업화학회 2003 공업화학 Vol.14 No.6
온실가스로 잘 알려진 이산화탄소의 배출을 줄이기 위한 집중적인 연구가 지난 10년간 진행되었다. 대부분의 연구는 탄소 공급원으로서의 이산화탄소를 다양한 환원제를 써서 촉매반응에 활용하는 것에 집중되었다. 특히 부가가치가 높은 화합물을 얻기 위한 촉매 반응에 있어 이산화탄소의 산소원자를 떼어내기 위해 수소가 사용되어왔는데, 이 수소화 촉매 공정이 상업화되지 못하는 원인은 기존의 수증기 개질 등의 공정에서 제조되는 수소의 비용이 수소화 반응을 거친 최종 생산물의 가격보다 비싸기 때문이다. 따라서 이에 대한 대안으로서 ‘온화한 산화제’ 그리고 산소 전달 물질로서 이산화탄소의 활용이 주목되고 있다. 이산화탄소로부터 기인한 표면 산소은 지방족 탄화수소 뿐만 아니라 방향족 탄화수소의 산화반응에 활성이 있는 것으로 확인되었다. 이러한 접근은 이산화탄소 활용 기술의 새로운 분야를 열 것으로 기대된다. 주목할 것은 최근 이산화탄소가 산화제로 작용하여 에틸벤젠 탈 수소화 반응에 적용될 때 촉매 활성화 함께 스티렌 선택성이 향상되는 것으로 알려졌다. 또한 공정에 사용되는 수증기를 이산화탄소로 대체할 경우 에너지 절감 및 열역학적 평형 전환율이 상승되는 이점을 얻을 수 있다. 본 총설에서는 탄화수소의 산화적인 전환을 위한 이산화탄소 산화제 활용에 대한 시도들에 대해 살펴보겠다. For the mitigation of global warming due to carbon dioxide, catalytic conversions of CO_(2) with hydrogen has been extensively studied for the last decade. Most of studies in this field have been concentrated on the utilization of carbon dioxide as a carbon source through catalytic reduction processes with various kinds of reductants. However, catalytic hydrogenation has confronted with some limitations to be commercialized because of the use of expensive hydrogen as a reductant. As an altermative way, the utilization of CO_(2) as a soft oxidant and an oxygen transfer agent is attracting considerable attention. The oxygen species have been proven to be active in the oxidative conversions of aromatic hydrocarbons as well as aliphatic hydrocarbons. This approach may be expected to open new technology for CO_(2) utilization. In particular, it was found that carbon dioxide plays a role as an oxidant to increase catalytic activity and selectivity to styrene in dehydrogenation of ethylbenzene. In addition, the use of CO_(2) with replacement of steam gave beneficial advantages such as energy saving and increase in equilibrium conversion. In this short review, we attempt to integrate recent efforts on CO_(2) utilization as a soft oxidant for oxidative conversions of hydrocarbons.
Sung-Ho Chang(장성호),Ji-Hoon Baek(백지훈),Jung-Eon Lee(이중언),Nematov Mirazamjon(Nematov Mirazamjon),Seok-Wan-Kang(강석완),Wang-Bum Lee(이왕범) 한국산업경영시스템학회 2018 한국산업경영시스템학회지 Vol.41 No.3
One of the most performed action in daily life is standing up from sitting position. As the population of the world is aging at the high rates, people may face problems with reduced muscle strength as well as psychological changes. This can lead elderly people having difficulties with standing up from chair. Now, with the aging trend worldwide, products are being developed that can support the lives of the elderly. This study examines the distribution of hip pressure in relation to the seating positions of the standing assistance seats under development to prevent standing up accidents in older adults. The currently developing standing assistant chair designed to tilt to a maximum angle of 25 degrees. At over 25°, design considers that older people are at risk of thrown back out of that force and that the forces exerted on their arms and legs can be a significant burden to older people. By considering danger of higher than 25° for older people which is experimented in the basis of static capturing approach in previous papers, it is experimented people with age group of 20~60 on 0° to 25° tilting angle on the basis of dynamic capturing method in order to pick convenient angle of inclination. Moreover, tried to find the optimum angle by comparing the hip pressure distribution when seated at the edge of the seat and at the center of the seat with the pressure distribution sensor.
BTA 드릴링에 있어서 모터 전류를 이용한 절삭이상상태 감시에 관한 연구
장성규,장성화,전언찬 동아대학교 공과대학부설 생산기술연구소 1998 生産技術硏究所硏究論文集 Vol.3 No.2
In the tube-seat working of heat exchanger using BTA drilling among the deep hole drilling process, this paper analyses the property about the tool breakage monitoring in the deep hole drilling as detect the current signal of main spindle motor and analyse the change of cutting force through the experiment for the workability measurement in the low-carbon steel and stainless. We obtain the following conclusions through this experiments. 1) We could detect the current of AC spindle motor through the indirect measuring system of cutting force without using the tool dynamometer. 2) We could observe the change of cutting force and tool breakage monitoring by detecting only the main spindle motor current in the deep hole drilling machine. 3) We could sufficiently observe tool breakage monitoring with detecting the main spindle motor current in BTA drilling process of deep hole drilling machine. 4) We could observe that the limit value approaches 20kg-cm in the 0.4mm range of flank wear.
공터키안(Empty sella)을 동반한 급성췌장염으로 발현된 부갑상선 선종 1예
전언주,오지혜,배경륜,장샛별,전승운,정의달,손호상,원규장 영남대학교 의과대학 2009 Yeungnam University Journal of Medicine Vol.26 No.1
The incidence of coexisting hyperparathyroidism and empty sella syndrome is rare and the etiology and incidence of their coexistence is not known. The association of hyperparathyroidism and the empty sella syndrome may be related to multiple endocrine neoplasia (MEN) syndrome due to a genetic disorder. We experienced a rare case of hyperparathyroidism presenting as acute pancreatitis combined with empty sella. We report here a 37-year old female who manifested epigastric pain because of acute pancreatitis. She had hypercalcemia due to parathyroid adenoma. A pituitary gland was not visible in the sella turcica on MRI scans. On genetic analysis, she did not show a mutation of the MENIN gene. Empty sella is thought to be a coincidental finding with hyperparathyroidism.
최상일,정연호,강창언 연세대학교 산업기술연구소 1984 논문집 Vol.16 No.1
A decorder is developed for correcting the single burst of errors. The convolutional code of Type-B2 is used for this purpose. This decoder has the ability to correct all bursts confined to m-l or fewer consecutive blocks with a guard space of the(m-1) consecutive error free blocks. A simple logical circuitry, having the same order of complexity as a pairity check circuit for a block code, is implemented to correct the errors in a communication system. The decoder used the (18,12) convolational code is designed and tested. Experimental results confirm the error-correcting ability.
쯔쯔가무시병의 진단에 사용되는 피동혈구응집법과 간접면역형광법의 비교 연구
이창섭,권근상,나상언,이흥범 대한감염학회 2008 감염과 화학요법 Vol.40 No.1
The gold standard for the serologic detection of scrub typhus is the indirect immunofluorescence assay (IFA), however the passive hemagglutination assay (PHA) is commonly used method in Korea because of its availability, easy handling. We compared the sensitivity of PHA and IFA to compare their effectiveness in diagnosing scrub typhus. Out of 35 patients who were eventually diagnosed of scrub typhus by positive IFA, 19 patients (54%) were also tested positive for PHA during the acute phase (titer=1:80). Whereas 30 patients (85%) were positive in IFA during the acute phase. During the recovery phase 30 (85%) patients were positive in PHA, whereas all patients were found to be positive in IFA. Patients with 4-fo1d or greater rise of antibody were 12 (34.3%) in PHA, and 19 (54.3%) in IFA. We note that IFA has better sensitivity over PHA in detecting scrub typhus.
니켈기 초내열합금 RENE 80 의 크리프시험중 결정입계 균열생성 및 전파
조창용,김학민,박용조,김승언,이상래 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.11
Two kinds of specimens with different microstructure were prepared by changing casting variables in vacuum investment casting. The effect of microstructural difference on the creep behavior, creep crack initiation and creep crack propagation was studied in Ni base superalloy RENE 80. The specimen having fine grained and uniformly distributed carbide exhibited superior creep properties to the large grained specimen tested at 760℃. However above 870℃, two kinds of specimens showed similar creep behavior. At higher temperature creep, crack initiation was principally caused by the reaction between the grain boundary exposed at the surface and the test atmosphere rather than the internal microstructural changes. The crack initiated at the surface propagated to the internal area and this kind of crack propagation leads to fracture of material.
레이저 인터페로메타를 이용한 드릴링 머신의 틸팅에 관한 연구
이승수,손영지,장성규,전언찬 동아대학교 공과대학부설 생산기술연구소 1996 生産技術硏究所硏究論文集 Vol.1 No.2
This paper describes tilt angle measurement method. This method measures tilt angle of drilling machine using laser interferometer with simple sliding linear bearing. Measurement method is next orders. First, measurement position is considered pointed contact of two probes. And revolution of drill axis deliver pointed contact of probe. Second, so laser interferometer attach on sliding linear bearing, moving of probe influence laser reflector. And laser program displays this vibration of laser reflector. Namely, this vibration is tilt factor. A lot of error factor have an effect on accuracy to measurement of linear, angular, and so on. But this paper ignores some error factor, because these error festor is very smaller than tilt angle factor which we had been measuring values.