슬러리 양돈분뇨의최적 고맥분리 방안연구

박성균(Seung-Kyun Park),최재길(Jae-Gil Choi),정윤진(Yoon-Jin Chung) 유기성자원학회 2000 유기물자원화 Vol.8 No.2

현재 국내에서 처리에 어려움을 겪고 있으며 사회적으로 문제가 되고 있는 양돈 분뇨의 처리중 생물학적 처리를 위한 전처리 공정의 일환으로 비육돈 슬러리 돈사에서 발생하는 분뇨를 대상으로 고액분려에 관한 연구를 수행하였다. 최적의 고액 분리를 위하여 적정 응집제 선정 및 첨가량을 도출하였으며 현장 규모의 고액 분리 장치를 통하여 규모별 최적 고액 분리 공정을 도출하였다. 이 결과 탈수성 개량을 위한 적정 응집제로는 Polyarcylamide계열의 양이온 고분자 응집제인 E-851이 적합하였으며, 단위 고형물당 O.24~O.6%가 요구되었다. 본 연구에서 검토된 공정으로는 Mesh Screen, Drum Screen, Cyclone Drum Filter, Screw Press, 고속 Screw Decanter, 저속 Screw Decanter 및 DAF 공정을 조합하여 검토하였다. 그 결과 최적 공정으로는 중 · 소규모의 1차 고액 분리 공정으로는 Screw Press(응집제 첨가)와 대규모 및 공공처리장 규모에서는 저속 Screw DecanterC응집제 첨가)가 적정 공정으로 도출되었으며 2차 처리 공정으로는 가압부상조가 가장 안정적인 것으로 나타났다. 한편 고액 분리 유무에 따라 수분조절제 및 유기물 부하량 감소는 각각 94.8, 84.7%로 나타났으며 슬러리 양돈분뇨의 정화방안으로는고액분리가반드시 필요한것으로나타났다. The swine wastewater from sluny feedlot has been a social problem in Korea since the proper treatment is very difficult. Therefore, a practical study on the Solid-Liquid separation of swine wastewater from slurry feedlot was carried out as a part of preatment for the successful biological treatment. The appropriate rype of coagulant and optimum dosage were proposed for the most efficient Solid-Liquid separation and the best Solid-Liquid separation methods for different size of feedlot were determined through the tests with fìeld-scaled 501id-Liquid separation equipment. The appropriate coagulant for the conditioning of dewatering property was E-851, which is a cationic polyelectrolyte made of polyacrylarnide, and the opùmum dosage was O .24~ O .6% of unit s이ids weight. Mesh Screen, Drum Screen, Cyclone Drum Filter, Screw Press, High-speed Screw Decanter, Low-speed Screw Decan ter, and Dissolved Air Flotation Process had been investigated in this study. According to the results, the Screw Press was the best dewatering equipment for the small & medium size for feedlot and lowspeed Screw Decanter was the best for the large size feεdlot & public owned treatment facilities for the primary Solid-Liquid separation, and the most suitable secondary treatment process was DAF. On the other hand, reductions for the requirement of bu1 king agent and organic loading by Solid-Liquid separarion procεss were 94.8% and 84.7%, respecrively. Therefore, the Solid-Liquid separarion process must be required for the successful rrearment of swine wasrewarer from slurry feedlot.

고감도 SQUID 냉각을 위한 저잡음 듀아의 설계 및 특성 조사

유권규,이용호,김기웅,권혁찬,김진목,Yu, K.K.,Lee, Y.H.,Kim, K.,Kwon, H.,Kim, J.M. 한국초전도학회 2010 Progress in superconductivity Vol.11 No.2

We have fabricated the low noise liquid helium(LHe) dewar with a different shape of thermal shield to apply the 64-channel SQUID(Superconducting Quantum Interference Device) gradiometer. The first shape of thermal shield was made of an aluminum plate with a wide width of 100 mm slit and the other shape was modified with a narrow width of 20 mm slit. The two types of dewars were estimated by comparing the thermal noise and the signal-to-noise ratio(SNR) of magnetocardiography(MCG) using the $1^{st}$ order SQUID gradiometer system cooled each dewar. The white noise was different as a point of the dewar. The noise was increased as close as the edge of dewar, and also increased at the thermal shield with the more wide width slit. The white noise of the dewar with thermal shield of 100 mm slit was 6.5 fT/$Hz^{1/2}$ at the center of dewar and 25 fT/$Hz^{1/2}$ at the edge, and the white noise of the other one was 3.5 - 7 fT/$Hz^{1/2}$. We measured the MCG using 64-channel SQUID gradiometer cooled at each LHe dewar and compared the SNR of MCG signal. The SNR was improved of 10 times at the LHe dewar with a modified thermal shield.

Structure of a DNA Duplex Containing a Site-Specific Dewar Isomer : Structural Influence of the 3'-T.G base pair of the Dewar product

Choi,Byong-Seok,Lee,Joon-Hwa The Korea Science and Technology Center 2000 BMB Reports Vol.33 No.3

In contrast to the pyrimidine (6-4) pyrimidone photoproduct [(6-4) adduct], its Dewar valence isomer (Dewar product) is low mutagenic and produces a broad range of mutations with a 42% replication error frequency. In order to determine the origin of the mutagenic property of the Dewar product, we used experimental NMR restraints and molecular dynamics to determine the solution structure of a Dewar-lesion DNA decamer duplex, which contains a mismatched base pair between the 3'-T residue and an opposed G residue. The 3'-T of the Dewar lesion forms stable hydrogen bonds with the opposite G residue. The helical bending and unwinding angles of the DW/GA duplex, however, are much higher than those of the DW/AA duplex. The stable hydrogen bonding of the G15 residue does not increase the thermal stability of the overall helix. It also does nt restore the distorted backbone conformation of the DNA helix that is caused by the forming of a Dewar lesion. These structural features implicate that no thermal stability, or conformational benefits of G over A opposite the 3'-T of the Dewar lesion, facilitate the perferential incorporation of an A. This is in accordance with the A rule during translation replication and leads to the low frequent 3'-T -> C mutation at this site.

액체 헬륨 듀아의 온도 특성 연구

이정희(Jung-Hee Lee),이영신(Young-Shin Lee),임현균(Hyun-Kyoon Lim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

The techniques of cooling down cryogen are used to make superconductors superducting state at very low temperature, 4 K. This paper studied on the temperature characteristic of liquid helium dewar. The dewar has a 30 L liquid helium capacity, a hold time of 5 days. The dewar has two thermal shield, 150K and 40K. The temperature was measured at the end of thermal shield and was compared with the thermal analysis. The thermal analysis of helium dewar were carried out with a finite element method program, ANASYS 10. The simulation result has predicted similar temperature data in manufactured helium dewar.

액체헬륨을 이용한 위성시험용 극저온패널 냉각시스템 개발 및 검증

조혁진(Hyokjin Cho),문귀원(Guee-Won Moon),서희준(Hee-Jun Seo),이상훈(Sang-Hoon Lee),홍석종(Seok-Jong Hong),최석원(Seok-Weon Choi) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

The cooling system utilizing liquid helium to chill the cryopanel (around 800 ㎜ by 700 ㎜ dimensions) down to 4.2 K was designed, implemented, and tested to verify the role of this cryopanel as a heat sink from the payload of spacecraft inside the large thermal vacuum chamber (effective dimensions: 8 m (Φ) × 10 m (L)) of KARI. Two LHe Dewars, one is main Dewar and the other is refilling Dewar, were used to supply liquid helium or cold helium gas into this cryopanel, and flow control for target temperature of the cryopanei within the requirement was done through fine adjustment of pressure inside the LHe Dewars. Return helium gas from the cryopanel was reused as a thermal barrier to minimize the heat influx on the core liquid helium supply pipe. Around three hours cooling time from ambient temperature to 40 K, the capacity to maintain the cryopanel at intermediate temperature, and 1K uniformity over the entire cryopanel surface at around 40 K with 20 W cooling power was verified through the test.

Direct Measurement of Thermal Noise and Eddy-current Noise Induced in Metals by Using a 1st-order SQUID Gradiometer

유권규,김기웅,이용호 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.61

We measured magnetic field noise induced in a copper disk, an aluminum disk and a brass disk for several conditions using superconducting quantum interference device gradiometer. The metallic samples were solid blocks, enamel-insulated dense coil-foils with several wire diameters, and a manually wound sparse coil winding. The metallic samples were positioned at 7 - 60 mm from the sensing coil of an axial first-order gradiometer with a baseline of 70 mm. Magnetic field noises were measured with the samples at room, liquid nitrogen and liquid helium temperatures. Intrinsic noises of the SQUID gradiometers were around 3 - 4 fT/Hz1/2. Depending on the material type, the shape of the sample, the distance from the sensing coil and the temperature of metal, the magnetic flux noise was different, increasing to the range of 6 - 100 fT/Hz1/2. We fabricated two-types of low-noise liquid-helium dewars with a different shapes of the metal plate for the thermal radiation shield for the multi-channel SQUID system for measuring the magnetocardiogram. We evaluated the fabricated dewars with comparing system noises and magnetocardiograms by using 64-channel SQUID gradiometer systems cooled in the fabricated dewars.

액체헬륨을 이용한 위성시험용 극저온패널 냉각시스템 개발 및 검증

조혁진(Hyokjin Cho),문귀원(Guee-Won Moon),서희준(Hee-Jun Seo),이상훈(Sang-Hoon Lee),홍석종(Seok-Jong Hong),최석원(Seok-Weon Choi) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.2

인공위성 적외선 탑재체의 열싱크 역할을 위해, 액체헬륨을 이용하여 극저온패널(가로 약 800 ㎜, 세로 약 700 ㎜)을 4.2 K까지 냉각시키는 시스템을 설계, 개발, 검증하였다. 유효직경 8 m, 유효 깊이 10 m의 대형열진공챔버에서 검증된 본 냉각시스템은 500리터 용량의 액체헬륨용기 두 개(극저온 패널로의 액체헬륨 또는 저온헬륨가스 주 공급용기 및 주공급용기로의 재충진용기)를 사용하였는데, 목표인 극저온패널의 냉각 및 온도제어는 주 공급용기 내부의 미세압력조절을 통해 액체헬륨 공급유량을 제어함으로써 이루었다. 극저온패널에 공급된 후 배기되는 저온 헬륨가스는 특별히 설계, 제작된 사중진공배관의 제3층을 흐르며 열차단막의 역할을 수행함으로써, 액체헬륨 공급 라인인 제1층(중심배관)으로의 열유입을 최소화하였다. 극저온패널을 상온에서 40 K(합성표준불확도 194 mK)까지 냉각시키는데 약 3시간이 소요되었으며, 20 W의 열을 발산하는 극저온패널을 40 K 주변 온도에서 1 K 이내의 온도균일도를 가지며 유지할 수 있었다. A cooling system utilizing liquid helium to chill the cryopanel (800 ㎜ × 700 ㎜ dimensions) down to 4.2 K was designed, implemented, and tested to verify the role of the cryopanel as a heat sink for the payload of a spacecraft inside the large thermal vacuum chamber (effective dimensions : 8 m (Φ) × 10 m (L)) of KARI (Korea Aerospace Research Institute). Two LHe (Liquid Helium) Dewars, one for the main supply and the other for refilling, were used to supply liquid helium or cold helium gas into this cryopanel, and flow control for the target temperature of the cryopanel within requirements was done through fine adjustment of the pressure inside the LHe Dewars. The return helium gas from the cryopanel was reused as a thermal barrier to minimize the heat influx on the core liquid helium supply pipe. The test verified a cooling time of around three hours from the ambient temperature to 40 K (combined standard uncertainty of 194 mK), the capacity for maintaining the cryopanel at intermediate temperatures, and a 1 K uniformity over the entire cryopanel surface at around 40 K with 20 W cooling power.

Structure of a DNA Duplex Containing a Site-Specific Dewar Isomer: Structural Influence of the 3'-T.G base pair of the Dewar product.

Lee, Joon-Hwa,Choi, Byong-Seok Korean Society for Biochemistry and Molecular Biol 2000 Journal of biochemistry and molecular biology Vol.33 No.3

In contrast to the pyrimidine (6-4)pyrimidone photoproduct [(6-4) adduct], its Dewar valence isomer (Dewar product) is low mutagenic and produces a broad range of mutations with a 42 % replicating error frequency. In order to determine the origin of the mutagenic property of the Dewar product, we used experimental NMR restraints and molecular dynamics to determine the solution structure of a Dewar·lesion DNA decamer duplex, which contains a mismatched base pair between the 3'-T residue and an opposed G residue. The 3'-T of the Dewar lesion forms stable hydrogen bonds with the opposite G residue. The helical bending and unwinding angles of the DW/GA duplex, however, are much higher than those of the DW/AA duplex. The stable hydrogen bonding of the G 15 residue does not increase the thermal stability of the overall helix. It also does not restore the distorted backbone conformation of the DNA helix that is caused by the forming of a Dewar lesion. These structural features implicate that no thermal stability, or conformational benefits of G over A opposite the 3'-T of the Dewar lesion, facilitate the preferential incorporation of an A. This is in accordance with the A rule during translesion replication and leads to the low frequent $3'-T{\rightarrow}C$ mutation at this site.

심자도 장비의 냉각장치 특성 최적화를 위한 기하 설계 변수 연구

이정희(Jung-Hee Lee),이영신(Young-Shin Lee),이용호(Yong-Ho Lee),임현균(Hyun-Kyoon Lim),이성진(Sung-Jin Lee) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.2

인체의 심장 활동에 의해 발생되는 생체 자기 신호를 심자도(magnetocardio-gram, MCG)라고 부른다. 이러한 생체자기장은 극저온 상태에서 고감도 자장센서인 SQUID(Superconducting QUantum Interference Device)를 사용함으로서 측정할 수 있다. 이 심자도 장비의 냉각장치는 액체 헬륨을 냉매로 사용하며 이 냉매를 보관하는 방법이 장비의 성능을 좌우한다. 액체 저온 듀아가 극저온 4 K에서 초전도 특성을 유지하기 위하여 사용된다. 본 연구에서는 액체 헬륨 듀아의 온도분포 특성이 연구되었다. 본 연구에서 사용된 듀아는 액체헬륨 용량이 30 L이고 5일간 유지된다. 듀아에는 150 K와 40 K의 이중 차폐체가 설치되었다. 열차폐체 끝단에서의 온도가 측정되었으며 전산모델의 해석결과와 비교되었다. 기하 설계 변수에 대한 최적화 기법을 적용하여 냉각장치인 저온 듀아의 열전단율을 최소화하였으며 듀아의 응력분포에 영향을 갖는 설계 기하 변수들의 특성을 연구하였다. 냉각장치의 열해석 및 최적화해석을 위해 유한요소 코드 ANSYS 10을 사용하였다. 저온 듀아에 사용된 전산모델은 열복사에 의한 영향을 최소화 할 수 있는 분야에서 온도 분포를 예측하는데 유용하게 사용될 수 있다. A magnetocardiogram (MCG) is a recording of the biomagnetic signals generated by cardiac electrical activity. Biomagnetic instruments are based on superconducting quantum interference devices (SQUIDs). A liquid cryogenic Dewar flask was used to maintain the superconductors in a superconducting state at a very low temperature (4 K). In this study, the temperature distribution characteristics of the liquid helium in the Dewar flask was investigated. The Dewar flask used in this study has a 30 L liquid helium capacity with a hold time of 5 d. The Dewar flask has two thermal shields rated at 150 and 40 K. The temperatures measured at the end of the thermal shield and calculated from the computer model were compared. This study attempted to minimize the heat transfer rate of the cryogenic Dewar flask using an optimization method about the geometric variable to find the characteristics for the design geometric variables in terms of the stress distribution of the Dewar flask. For thermal and optimization analysis of the structure, the finite element method code ANSYS 10 was used. The computer model used for the cryogenic Dewar flask was useful to predict the temperature distribution for the area less affected by the thermal radiation.

Analysis and reduction of thermal magnetic noise in liquid-He dewar for sensitive low-field nuclear magnetic resonance measurements

S.-m. Hwang,K. K. Yu,Y. H. Lee,C. S. Kang,K. Kim,S. J. Lee 한국초전도저온학회 (구 한국초전도저온공학회) 2013 한국초전도저온공학회논문지 Vol.15 No.2