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CANTiM 합금의 변태특성 및 형상기억능에 미치는 가공열처리의 영향
The purpose of this study is to investigate the distribution of the second phase, the change of transformation temperature and mechanical properties with thermomechanical treatment conditions by means of metallography, calorimetry, XRD, EDS, tensile test and fractography in a CuAlNiTiMn alloy. (1) The cast structure contains Ti-rich precipitates between dendrite arms, which have been identified as (Cu,Ni)_(2)TiAl intermetallic compounds. The microstructure of the specimen homogenized at 850℃ still reveals cast structure, but martensite plates were well developed. With increasing homogenizing temperature in the order of 900℃, 950℃ and l000℃, however, the Xs phase was precipitated in matrix, and the volume fraction of it was increased. (2) When hot-rolled specimen was betatised at 750℃ for l0min, recrystallization could not be observed. But the specimen betatized at 800℃ for l0min was partially recrystallized and most of X_(L) phase was melted in matrix. In betatizing above 850℃, the grain was mostly recrystallized and the X_(S) phase was precipitated in matrix. When hot-rolled specimen was betatized at 750℃ for 30min, recrystallization could not be observed. The grain was mostly recrystallized by betatizing above 800℃ but α and □ phase was observed by β→α+□ reaction. M, and A, temperatures were risen with lowering betatizing temperature and increasing holding time. (3) The elongation of the specimen betatized at 800℃ for 30min was 8.2% as a highest value, but it was decreased upto 5% with increasing betatizing temperature. With increasing betatizing temperature in the order of 750℃ and 800℃, the fracture mode has changed to the mixture of cleavage fracture and ductile fracture, and to ductile fracture with fine precipitates within dimple. In the specimen betatized above 850℃, the size of dimple became larger and shape of it was not uniformed. (4) When the specimen is betatized at 850℃ for 30min, shape recovery rate could be obtained maximum value by 98%.
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대규모 실내체육관의 냉난방설비 시스템의 에너지성능 분석 및 경제성 평가에 관한 연구
김춘동 대구가톨릭대학교 대학원 2012 국내석사
The domestic by field energy consumption occupies the industry 55%, building 25%, and conveyance 21% but the energy consumption of the building is the tendency that it rises a lot. The building can classify the energy consumption into the building section, mechanical part, and international telecommunication union-telecommunication sect. And the energy consumption saving this mechanical part is possible through the acceptance of the energy material of the high efficiency and control. Thus, the heat source facility applied to the enormous building in which the amount of energy consumption sets based on many enormous buildings and which is built against this indoor stadium through the comparing analysis of the calculation of the indoor thermal load according to the plan of the heat source facility and amount of energy consumption afterward is presented. The profitability of the long-term view is evaluated and economic cooling and heating system try to be proposed. The comparing analysis of the calculation of the indoor thermal load according to the plan of the heat source facility and amount of energy consumption were performed by the method of study for the indoor stadium. The seal type space of the gymnasium and dome structure was selected as the examination object building among the domestic enormous indoor stadium. It sets up based on the gross floor area 10,000㎡ or greater built after 2000 years and 5 target groups are selected and the standard for selection grasps the heat source facility of each target group. The thermal load in the room according to the plan of the heat source facility and amount of energy consumption are compared and are analyze with the simulation which selects the mountain around capital gymnasium and uses TRNSYS. Many alternatives of the applicable heat source facility are selected and LCC economical efficiency valuation is performed and the equipment system in which the adaptability is the highestest among is calculated.
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광 음향 효과를 이용한 전력기기의 휴대용 유중 가스분석 기술 : 광 음향효과이용 유중가스분석
현재 국내에서 사용되는 유중가스분석 장비는 주로 고가의 고정형 장비가 대부분으로 시료를 수동으로 채취 및 운반하고 분석하기 때문에 전력기기의 이상유무의 진단과 대응까지는 많은 시간이 소요될 뿐만 아니라 급속히 진행되는 이상발생시 효과적인 대응하기 어렵다. 이러한 이유로 기존의 고가의 고정형 설비를 대신할 수 있고, 휴대성이 편리한 소형의 유중가스분석장치가 필요하며, 이를 통해 상대적으로 안전성이 취약한 장비분석 횟수를 늘임으로서 전체 전력기반의 안전성을 높일 수 있다[4]. 따라서 본 연구에서는 기존의 고정형 유중가스분석장치를 사용하여 발생하는 직간접적인 문제를 해소하기 위하여 PAS(photo-acoustic spectroscopy)기반의 소형화된 휴대용 유중가스분석장치를 연구하고 이를 실험적으로 검토하였다. 연구된 장치는 유중가스분석을 위해 절연유내에 함유된 미량의 가스를 추출하여 전력 기기내의 비정상적인 열적 스트레스에 대한 정보를 검출한다. 검출된 정보는 분석되어 전력기기의 안정성을 평가하게 한다. 본 장치는 기존의 해외 의존 장비와 달리 실시간 정보처리를 하여 전력기기의 안정성을 현장에서 바로 판단할 수 있게 하였다. In a highly industrialized society, the electric power has been used in various forms. The aging power divices and the degradation and abnormal operation of power units may cause blackouts of the electricity. Even a momentary power failure have a tremendous ripple effects in our society. Therefore, A steady inspection management of power divices is required to have a stable supply of electric power. To monitor the status of power units, the dissolved gas analysis is often used. The conventional dissolved gas analysis method is not only time consuming but also not effective to the ongoing situations of power units because the sample taken from the troubled power unit should be transferred to the lab where the analysis facility is. To resolve this difficulty, this thesis presents a potable dissolved gas analyzer which uses the photoacoustic spectroscopy. This study consists of the design and fabrication fo the photoacoustic spectroscopy device, gas measurement and data processing system, magnetic bubble ring gear system, detector circuit, and embedded computing system with corresponding programs. To verify the performance of the proposed potable dissolved gas analyzer, the results of experiments are compared with those of the conventional dissolved gas analysis on the same gas samples from the insulating oil. For comparison, the error rate of data is calculated with reference to the data of the conventional dissolved gas analysis. And the repeatability of the proposed system is estimated by repeating experiments. As a result, for most concerned gases, the error rate target of 15% and the repeatability target of 15% are satisfied. Therefore, when the proposed portable dissolved gas analyzer is used for the analysis of oil gas in power units, the in-situ analysis of the gases makes the prompt response to the abnormal operation of units possible increasing the stability of the power units. In the future, this system can be applied to other various applications which require gas analysis.
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IPN's of Polyurethane/Natural Rubber with Reactive Compatibilizer
폴리우레탄(PU)과 천연고무(NR)를 조성고분자로 하고 상호침투하는 고분자 구조(Interpenetrating Polymer Network : IPN)를 제조함에 있어서, 조성고분자간 상호작용하는 반응성 상용화제를 도입하였으며, 이의 함량과 PU/NR의 조성비를 변화시켜 PU/NR IPN을 동시중합법으로 합성하였다. 조성고분자간 상호작용하는 반응성 상용화제로 maleic anhydride(MAH)를 선택하였고, PU 조성과는 maleimide-terminated urethane을 형성하게 하고 NR과는 그라프트 반응을 유도하였으며, 반응성 상용화제인 MAH와 각각의 조성 고분자와의 반응을 FT-IR로 확인 하였다. 톨루엔 내에서 Benzoyl Peroxide(BPO)를 개시제로 사용하여 천연 고무에 MAH를 그라프트시킨 maleic anhydride grafted natural rubber(NR-g-MAH)를 용액 그라프트법(solution grafting method)으로 제조하였고, 이를 NR 조성에 포함시켜 반응성 상용화제의 함량을 변화시켰다. PU/NR IPN은 NR과 NR-g-MAH를 톨루엔에 완전히 용해시키고, 천연고무의 가교제인 divinyl benzene(DVB)과 개시제인 BPO를 투입한 후 균일하게 교반하였고, 천연고무 조성물의 혼합액에 일정한 조성비에 따라 폴리우레탄의 조성물인 polytetramethylene ether glycol(PTMEG)과 4,4'-diphenylmethane diisocyanate(MDI) 그리고 가교제인 trimethylolpropane(TMP)을 차례로 투입한 다음 동시중합법으로 적정 시간 동안 반응시키고, Petri-dish에 부은 후 내부의 반응물을 80℃ 오븐에서 24시간 동안 완전히 반응시킨 후 80℃ 진공 오븐에서 용매를 완전히 제거하여 합성하였다. IPN 합성시의 제반 변수가 조성 고분자간 상호침투도 및 최종 생성물의 물성에 미치는 영향을 비교·검토하기 위하여 밀도, 경도, 용매에서의 팽윤비, 기계적 성질, 동적 기계적 성질 등을 조사하였다. PU와 NR의 함량이 동일하고 반응성 상용화제의 함량을 달리하여 제조한 IPN은 MAH의 함량이 증가함에 따라 조성간 반응이 증가하여 인장강도 등의 기계적 성질과 DMA에 의하여 측정된 동적 기계적 성질, elastic modulus가 향상되었다. 또한, 조성간 상호침투도가 증가하여 밀도와 경도가 증가하였으며, PU와 NR간 상용성이 향상되어 용매에 대한 팽윤도가 감소하였다. PU와 NR의 조성비를 변화시켜 제조한 IPN은 MAH를 첨가하지 않은 경우, 각각의 조성고분자의 함량에 비례하는 물성거동을 나타내었으며, 상용화제를 첨가하여 제조한 IPN은 모든 조성에서 보다 향상된 물성 거동을 보였다. 본 연구의 결과 PU와 NR의 두 조성에 조성간 상호 반응하는 상용화제를 첨가함으로써 조성간 상분리가 억제되어 상호침투도가 증가하였으며, 이로 인해 상용성이 향상되어 전체적인 물성이 향상됨을 알 수 있었다. 또한, 각각의 결과로부터 구조-물성거동 간에 서로 밀접한 상관관계가 있음을 알 수 있었다. Interpenetrating polymer networks(IPN's) of polyurethane(PU) and natural rubber(NR) with different composition of PU and NR, amount of reactive compatibilizer, were synthesized through simultaneous solution polymerization. Maleic anhydride(MAH) was selected as a reactive compatibilizer between PU and NR, the each reactions between reactive compatibilizer and NR, ending isocyanate groups in MDI were confirmed with FT-IR. Maleic anhydride grafted natural rubber(NR-g-MAH) was synthesized with benzoyl peroxide(BPO) in toluene at 80℃. And NR-g-MAH was included in NR composition. PU/NR IPN's were synthesized as fllow. NR and NR-g-MAH were dissolved throughly in toluene. When the dissolution was completed, divinyl benzene(DVB) as the for crosslinking agent as well as BPO was added. After uniform stirring, polytetramethylene ether glycol(PTMEG), 4,4'-diphenylmethane diisocyanate(MDI), and trimethylolpropane(TMP) were added in NR solution. After proper reaction, the mixture was poured into petri-dish and reacted in a drying oven at 80℃ for 24hrs. Finally, the product was dried in a vacuum oven at 80℃ for another 24hrs. Density, hardness, swelling ability on toluene, mechanical property and dynamic mechanical property of the final products were investigated and analyzed to evaluate the effect of PU/NR composition and reactive compatibilizer. For PU/NR IPN's with different amount of MAH; the properties of density, hardness were improved and swelling ratio was lowered with increasing the reactive compatibilizer. Mechanical property, dynamic mechanical property, and elastic modulus were also improved. For the PU/NR IPN's with different PU/NR composition, the properties were proportion to the each composition ratio. From the above results, the general properties of PU/NR IPN were improved, because of the improved compatibility triggered by inhanced interpenetration due to reactive compatibilizer.
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