한국 초파리집단의 선택불리에 관한 지구 자기장의 5배인 자기장의 영향

박은규,정승문,김중현,최오목 圓光大學校 1995 論文集 Vol.29 No.2

본 연구에서는 한국 선유도의 자연집단 야생형 초파리와 가시돌연변이형 황색체-소시 초파리를 Helmholtz coils 장치를 이용해서 유도한 지구 자기장의 5배인 자기장내의 집단과 비교 집단인 지구 자기장내의 집단에서 발생율 변동과 성적 선택빈도를 조사하여, 선택불리에 관한 유전적 행동을 관찰해서 다음과 같은 결과를 얻었다. 1.야생형 유전자(+)를 운반하는 염색체의 선택빈도는 15세대까지 평균 빈도가 지구 자기장의 5배인 자기장내의 초파리 집단, 지구 자기장내의 초파리 집단이 각각 0.6489, 0.6553으로 관찰되었다. 이 결과는 지구 자기장의 5배인 초파리 집단에서 더 강한 선택불리 행동을 보여 주었다. 2.초파리 집단의 발생율 변동은 지구 자기장의 5배인 자기장내의 초파리 집단 3세대(13.60%), 지구 자기장내의 초파리 집단 6세대(22.35%), 8세대(22.30%)에서 아주 낮은 발생율의 변동을 보여주었으며, 2개의 상이한 자기장내 초파리 집단의 전체 평균 발생율은 지구 자기장의 5배인 자기장내의 초파리 집단, 지구 자기장내의 초파리 집단에서 각각 58.07%, 41.93%로 관찰되었으며, 후자보다 전자에서 발생율이 증가함을 보여 주었다. 3.돌연변이형 황색체-소시 유전자(ym)를 운반한 염색체의 선택빈도는 각각의 자기장내의 초파리 집단에서 0.0542, 0.0646으로 관찰되었다. 이 결과는 지구 자기장의 5배인 자기장내의 초파리 집단에서 0.0542로 상대적으로 강하게 선택불리 행동을 보여 주었다. 4.돌연변이형 황색체 유전자(y)를 운반한 염색체의 선택빈도는 각각의 초파리 집단에서 0.0185, 0.0144로 관찰되었다. 이 결과는 비교 집단인 지구 자기장내의 초파리 집단에서 0.0144로 더 강한 선택불리 행동을 보여 주었다. 5.돌연변이형 소시 유전자(m)을 운반한 염색체의 선택빈도는 각각의 조절된 자기장내의 초파리 집단에서 0.0328, 0.0190으로 관찰되었다. 이 결과도 지구 자기장내의 초파리 집단에서 0.0190으로 상대적인 강한 선택불리 행동을 보여 주었다. 6.수컷이 가지고 있는 Y-염색체의 선택빈도는 각각의 초파리 집단에서 0.2457, 0.2467로 관찰되었다. 이 결과는 지구 자기장의 5배인 초파리 집단에서 0.2457로 더 높은 선택불리 행동을 보여 주었다. 7.Duncan's multiple range test의 LSD값으로 유의 차이 유무 검정을 하였던 바 야생형 유전자의 A 그룹과 돌연변이형 유전자들의 B 그룹사이에서 고도의 유의 차이가 있음이 밝혀졌다. To elucidate the genetic behavior of selective disadvantage among visible mutants of Drosophila melanogaster bred and kept by the genetic study laboratory room. Wonkwang University and the wild type collected at Sunyoudo island in Korea, and reared under the influence of two different strength of magnetic fields, i.e. the quintuple and the ambient magnetic field, this study was carried out at the above indicated laboratory room. 1.The mean selective frequencies of wild gene(+)-carry chromosome up to 15th generation, affected by two different magnetic fields, showed 0.6489 and 0.6553 with the magnetic field strength as mentioned order before. The data explains that the population of Drosophila melanogaster reared in the quintuple magnetic field showed higher selective disadvantage. 2.The variations of emergence rates of the populations of Drosophila melanogaster altering by generation showed the drastic lowest values at the specified generation, for example, 13.60% under the quintuple magnetic field at the third generation and 22.35% and 22.30% under the ambient magnetic field at the 6th and 8th generation. The over-all mean emergence rates of the populations of Drosophila melanogaster reared in controlled magnetic fields, i.e. the quintuple and the ambient magnetic fields using Helmholtz coils, showed 58.07% and 41.93% respectively. Referring to these data, the population of flies raised in the quintuple magnetic field showed a relatively higher emergence rate than the ambient magnetic field. 3.The mean selective frequencies of the individual of ym gene-bearing chromosomes showed 0.0542 and 0.0646 by the same order of magnetic field strength indicated above. It was shown that the population of flies reared in the quintuple strength generated by Helmholtz coils cleared the relatively strong selective disadvantage being 0.0542. 4.The mean selective frequencies of the mutant that carries y gene-bearing chromosome showed 0.0185 and 0.0144 from the two different magnetic fields in the same magnetic order. The results indicated that the population of flies from the ambient magnetic field showed higher selective disadvantage frequency, 0.0144. 5.The mean selective frequencies for the mutant carrying m gene-bearing chromosome were calculated as to be 0.0328 and 0.0190 for the same order of magnetic field strength. The found from this results is that the selective disadvantage behavior for the mutant rearing m gene chromosome in the ambient magnetic field was stronger than the one, being 0.0190. 6.The mean selective frequencies of the male flies which carries Y-chromosome showed 0.2457 and 0.2467 respectively. The results indicated that the male flies from the quintuple magnetic field showed higher selective disadvantage being 0.2457. 7.Through Duncan's multiple range test and LSD value, the highly significant differences between A group of the wild type and B group of the other three mutants were calculated.

A Magnetic Field Separation Technique for a Scaled Model Ship through an Earth’s Magnetic Field Simulator

Hyun-Ju Chung,Chang-Seob Yang,Woo-Jin Jung 한국자기학회 2015 Journal of Magnetics Vol.20 No.1

This paper presents an experimental technique to accurately separate a permanent magnetic field and an induced one from the total magnetic fields generated by a steel ship, through compensating for the Earth’s magnetic field. To achieve this, an Earth’s magnetic field simulator was constructed at a non-magnetic laboratory, and the field separation technique was developed, which consisted of five stages. The proposed method was tested with a scaled model ship, and its permanent and induced magnetic fields were successfully extracted from the magnetic field created by the ship. Finally, based on the separated permanent magnetic field data, the permanent magnetization distribution on the hull was predicted by solving an inverse problem. Accordingly, the permanent magnetic fields generated by the ship can easily be calculated at any depth of water.

초파리 집단의 선택불리에 관한 지구자기장 2배의 자기장 영향

김은태,정승문,박은규 圓光大學校 1996 論文集 Vol.31 No.2

본 연구에서는 한국 거제도의 자연집단 야생형 초파리와 가시돌연변이형 황색체-백색안 초파리를 Helmholtz coils장치를 이용해서 유도한 지구자기장 2배의 자기장내의 집단과 비교 집단인 지구자기장내의 집단에서 발생된 성적 선택빈도를 조사하여, 선택불리에 관한 다음과 같은 유전적 행동의 결과을 얻었다. 초파리 집단의 전체 평균 발생율은 Helmholtz coils장치를 이용해서 유도한 지구 자기장 2배의 지기장내의 집단과 지구자기장내 집단에서 각각 55.10%와 44.90%로 관찰되었다. 이 결과는 지구자기장내의 초파리 집단의 발생율이 지구자기장 2배의 초파리 집단의 발생율보다 상대적으로 낮은 수치로 조사되었다. 야생형 유전자를 운반한 염색체의 선택빈도는 20세대까지 전체 평균빈도가 위의 양집단에서 각각 0.7177과 0.7180으로 관찰되었다. 이 결과는 지구자기장 2배의 자기장 집단에서 더 높은 선택불리 행동을 보여 주었다. 돌연변이형 yw 유전자를 운반한 염색체의 선택빈도는 각각의 조절된 자기장내의 초파리 집단에서 각각 0.0349와 0.0372로 관찰되었다. 이 결과도 지구자기장 초파리 집단보다 지구자기장 2배의 자기장 초파리 집단에서 더 강한 선택불리를 보여 주었다. Duncan's multiple range test와 LSD값으로 유의차이 유무를 검정하였던 바 야생형 그룹과 다른 3개의 돌연변이형 그룹사이에서 고도의 유의차이가 있음이 밝혀졌다. To elucidate the genetic behavior of selective disadvantage among sex-linked mutants of Drosophila melanogaster bred and kept by the genetic study laboratory room, Wonkwang University and the wild type collected at Keojaedo island, and reared under the influence of two different strength of magnetic fields, i.e. the double and the ambient magnetic field, this study was carried out at the above indicated laboratory room. The over-all mean emergence rates of Drosophila melanogaster populations reared in controlled magnetic fields, i.e. the double using Helmholtz coils and the ambient showed 55.10% and 44.90% respectively. Referring to these data, the fly population raised in the ambient magnetic field showed a relatively lower emergence rate than the double magnetic field population. The mean selective frequencies of wild type gene-carrying chromosomes up to tweentieth generation, affected by two different magnetic fields, showed 0.7177 and 0.7180 with the magnetic field strength as mentioned other before. The data explains that Drosophila melanogaster population reared in the double magnetic field showed higher selective disadvantage. The selective frequencies of the individual of yw gene-bearing chromosomes showed 0.0349 and 0.0372 by the same order of magnetic field strength indicated above. It was shown that the fly population reared at the double strength generated by Helmholtz coils cleared the relatively strong selective disadvantage being 0.0349, however the opposite value was 0.0372 resulted from the ambient magnetic field. Through Duncan's multiple range test and LSD value, the highly significant differences between the wild type and anyone of the other three mutants were calculated.

Fabrication and magnetic properties of hexagonal BaFe12O19 ferrite obtained by magnetic-field-assisted hydrothermal process

Min Zhang,Jianming Dai,Qiangchun Liu,Qiang Li,Zhenfa Zi 한국물리학회 2018 Current Applied Physics Vol.18 No.11

High magnetic field effects on the microstructure and magnetic properties of BaFe12O19 hexaferrites synthesized hydrothermal method have been investigated. The obtained results indicate that the lattice constant decreases gradually as the magnetic field strength increases, which may be attributed to the lattice distortion resulted from the high magnetic field. Polycrystalline BaFe12O19 samples prepared under magnetic field strength at zero and 5 T are single phase. It is found that application of external magnetic field during synthesis can induce orientated growth of the hexaferrite crystals along the easy magnetic axis. The magnetic properties can be effectively regulated by an application of high magnetic fields. It is observed that the BaFe12O19 prepared under a 5 T magnetic field exhibits a higher room-temperature saturation magnetization (66.3 emu/g) than that of the sample (43.6 emu/g) obtained without magnetic field. The results can be explained as the enhanced crystalline, improvement of Fe3+ ions occupancy and the oriented growth induced by the external magnetic field. The growing orientation of particles gives rise to increased coercivity due to the enhancement in shape anisotropy. It is expected that an application of magnetic field during the formation of magnetic nanoparticles could be a promising technique to modify magnetic properties with excellent performance.

Flow response of magnetic fluid surface by pitching motion

Bae, Hyung-Sub,Yun, Young-Won,Park, Myeong-Kwan The Korean Society of Mechanical Engineers 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.2

This research analyses the dynamic behavior of magnetic fluid that sloshes due to the pitching motion of the container. To analyze the behavior of magnetic fluid, we first analyze the equations that govern magnetic fluid as well as the momentum equation of the sloshing that results from a magnetic field. In each case, we conducted simulation and compared the results from simulation with those from experiments. When sloshing does not occur, the surface of the magnetic fluid rises towards the location of intensity of the magnetic field; in the absence of an additional, external body force, the fluid remains elevated. In case sloshing occurs simultaneously with the application of the magnetic field, the elevation of the surface as a result of the magnetic field is maintained. Further, we can confirm that if the excitation frequency of sloshing is small, the wave motion of the surface is small because the magnetic body force dominates the effect of sloshing. Even if the excitation frequency increases, the wave motion of the fluid surface is smaller than when a magnetic field is not applied. The fluid surface rises in that location where the intensity of the magnetic field is strong. Where the intensity of the magnetic field is weak, the height of the fluid surface is lower than the initial level that obtains in the absence of a magnetic field. Through the study, we can conclude that the sloshing behavior of magnetic fluid is influenced by the magnetic field intensity and distribution.

Assessment of Magnetic Field Mitigation and Electrical Environmental Effects for Commercially Operating 154kV Transmission Lines with Passive Loop

Lee, Byeong-Yoon,Myung, Sung-Ho,Ju, Mun-No,Cho, Yeun-Gyu,Lee, Dong-Il,Lim, Yun-Seog,Kim, Sang-Beom The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.3

Power frequency magnetic field is still a critical problem for new construction of overhead power transmission lines in Korea because most people have been concerned about possibly carcinogenic effects of it. Although reference level of power frequency(60Hz) magnetic field has been set to 200uT in ICNIRP guidelines published in 2010, Korean government has no intention of adjusting 83.3uT specified by law in 2006 to this new reference level in consideration of people's concerns for the time being. Regardless of the current regulated magnetic field value, electric utility company has been trying to reduce magnetic field in the residential area in the vicinity of overhead power transmission lines to take into account of public concerns on the long-term effect of magnetic fields. In an effort to reduce magnetic field, engineering side has made considerable efforts to develop passive loop based, cost-effective mitigation technique of power frequency magnetic field more than ten years. In order to verify developed power frequency magnetic field mitigation technique based on passive loop, a horizontal type of passive loop was designed and installed for commercially operating 154kV overhead power transmission line for the first time in Korea. The measurement results before and after the installation of passive loop showed that magnetic field could be reduced to about 20%. The electrical environmental effects such as AN, RI and TVI were assessed before and after the installation of passive loop and these values were complied with the requirements specified by electric utility. It has been confirmed from the field test results that passive loop could be commercially and cost-effectively utilized to mitigate power frequency magnetic field.

Assessment of Magnetic Field Mitigation and Electrical Environmental Effects for Commercially Operating 154kV Transmission Lines with Passive Loop

Byeong-Yoon Lee,Sung-Ho Myung,Mun-No Ju,Yeun-Gyu Cho,Dong-Il Lee,Yun-Seog Lim,Sang-Beom Kim 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.3

Power frequency magnetic field is still a critical problem for new construction of overhead power transmission lines in Korea because most people have been concerned about possibly carcinogenic effects of it. Although reference level of power frequency(60Hz) magnetic field has been set to 200uT in ICNIRP guidelines published in 2010, Korean government has no intention of adjusting 83.3uT specified by law in 2006 to this new reference level in consideration of people’s concerns for the time being. Regardless of the current regulated magnetic field value, electric utility company has been trying to reduce magnetic field in the residential area in the vicinity of overhead power transmission lines to take into account of public concerns on the long-term effect of magnetic fields. In an effort to reduce magnetic field, engineering side has made considerable efforts to develop passive loop based, cost-effective mitigation technique of power frequency magnetic field more than ten years. In order to verify developed power frequency magnetic field mitigation technique based on passive loop, a horizontal type of passive loop was designed and installed for commercially operating 154kV overhead power transmission line for the first time in Korea. The measurement results before and after the installation of passive loop showed that magnetic field could be reduced to about 20%. The electrical environmental effects such as AN, RI and TVI were assessed before and after the installation of passive loop and these values were complied with the requirements specified by electric utility. It has been confirmed from the field test results that passive loop could be commercially and cost-effectively utilized to mitigate power frequency magnetic field.

Dependence of the Magnetic Energy Barrier on the Strength of the Applied Magnetic Field in Nanostructured Cells of Exchange-Coupled Trilayers

J. K. Han,C. W. Han,임상호 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6

In this study, the change in the magnetic energy barrier is investigated as a function of the applied magnetic field. Elliptical nanostructured cells of exchange-coupled trilayers that have lateral dimensions of 160 nm (long axis) × 80 nm (short axis) are considered for various values of the thickness asymmetry for the two magnetic layers. An accurate analytical equation for the total energy, which includes effective magnetostatic fields averaged over the entire magnetic layer is used. In the absence of the thickness asymmetry, the magnetic energy barrier initially decreases slowly with increasing the magnetic field, followed by a steeper decrease in the intermediate field range. However, in the presence of thickness asymmetry, the decrease in the magnetic energy barrier occurs quite steeply even at small magnetic fields, and this tendency increases with increasing thickness asymmetry. Consequently, as the thickness asymmetry increases, the applied field dependence of the magnetic energy barrier approaches that observed for a single-layered thin film. A significant reduction of the magnetic energy barrier is observed by using the simplifying assumption concerning the magnetostatic fields which was frequently used in the past. This clearly emphasizes the importance of using an accurate equation for the total energy in calculating the magnetic energy barrier of nanostructured exchanged-coupled trilayers.

BiPbSrCaCuO 초전도 자기검출소자

이상헌,이성갑,이영희 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.5

The magnetic field sensor was fabricated with superconducting ceramics of BiPbSrCaCuO system. The sensor at liquid nitrogen temperature showed the increase of electrical resistance by applying magnetic field. Actually, the voltage drop across the sensor was changed from zero to a value more than 100 $\mu\textrm{V}$ by the applied magnetic field. The change of electrical resistance depended on magnetic field. The sensitivity of this sensor was 2.9 $\Omega$/T. The sensing limit was about 1.5${\times}$10$\^$-5/ T. The increase of electrical resistance by the magnetic field was ascribed to a modification of the Josephson junctions due to the penetrating magnetic flux into the superconducting material. Considering the observed properties of the superconductor with trapped magnetic flux, a magnetic sensor was fabricated to detect simultaneously both the intensity and the direction of the magnetic field.

원형무코일로 구성된 MRI용 초전도 자석의 설계와 비교

김용권(Yong-Gwon Kim),현정호(Jung-Ho Hyun),서증훈(Jeung-Hoon Seo),김혁기(Hyug-Gi Kim),오창현(Chang-Hyun Oh) 大韓電子工學會 2011 電子工學會論文誌-SC (System and control) Vol.48 No.6

본 논문에서는 초전도 자석의 자장 균일도를 개선하기 위한 방법으로 3가지 형태의 magnet 모델을 제안하고 각각의 자석형태에 대하여 같은 세기의 자장을 (Magnet field strength) 가질 경우에 최소전력 방식으로 최적화된 전류 분포에 해당하는 coil wire의 길이 그리고 해당 조건에서의 자장의 불균일도를 시뮬레이션을 통하여 비교 분석하였다. 구성된 3가지 magnet type을 동일한 조건 (계산 점의 개수 18개 20㎝ DSV)에 대해서 wire길이와 main field inhomogeneity를 비교하였으며 이러한 시뮬레이션 결과를 통하여 얻을 수 있는 결론은 계산점의 수가 적을수록 wire의 길이는 짧아지나 field inhomogeneity는 높아진다는 것이다. 즉 Magnet shim을 수행할 경우 계산점을 줄이는 방법으로는 짧은 wire의 길이와 main field homogeneity를 동시에 만족하도록 최적화 하는 것이 거의 불가능함을 의미하는 것이다. 그러나 DSV를 줄였을 경우에 계산점을 줄였을 때에 비해 우수한 결과 값을 얻을 수 있었다. 결론적으로 공간적으로 개방되어 있는 magnet model의 경우 계산점을 줄여 shimming을 진행할 경우 동일한 imaging region의 크기에 대해 더 많은 전류(또는 wire 길이)가 필요하고 field 균일도도 떨어졌으나 작은 ROI를 대상으로 영상을 얻는 경우 유용하게 사용될 수 있다. This paper proposed a method which is the three types of magnet model for improving field inhomogeneity of superconducting magnet. The length of coil wire was compared for the optimized current pattern using minimum power methods and field inhomogeneity under the specific simulation condition in case of same magnet field strength about each magnet type field inhomogeneity. Length of wire and field inhomogeneity were compared under the same condition(18 target points 20㎝ DSV). According to the simulation results the smaller target points can reduce the wire length but it can not improve the field inhomogeneity. Length of wire and low field inhomogeneity can not improve in same time. However small DSV and reducing target points can overcome the these problem. And to conclude if it processes shimming as reducing target points in case of magnet model which is open to space about the size of same imaging region it needs a lot of current values( or the length of wire) and decreases field homogeneity but it is useful to get small ROI.