• Title/Summary/Keyword: Irregular field

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A Study of the Domain Structure of Polycrystalline MnZn Ferrites (Bitter Method를 이용한 다결정 MnZn 페라이트의 자구 구조 관찰)

  • 안성진;김창경;변태영;홍국선
    • Journal of the Korean Magnetics Society
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    • v.10 no.3
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    • pp.143-148
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    • 2000
  • We made MnZn ferrites by conventional ceramic processing method and observed magnetic domain structures by Bitter method. The Bitter method revealed that the domain structure of the surface is stripe-like. When a magnetic field was applied, the domain wall motion was observed during the initial magnetization process and the irregular motion of domain wall or domain rotation was observed near the saturation magnetic field (90∼120 Oe).

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Supersonic Jet Noise Control via Trailing Edge Modifications

  • Kim, Jin-Hwa;Lee, Seungbae
    • Journal of Mechanical Science and Technology
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    • v.15 no.8
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    • pp.1174-1180
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    • 2001
  • Various experimental data, including mixing areas, cross correlation factors, surface flow patterns on nozzle walls, and far field noise spectra, was used to draw a noise control mechanism in a supersonic jet. In the underexpanded case, mixing of the jet air with ambient air was significantly enhanced as presented before, and mixing noise was also dramatically reduced. Screech tones, in the overexpanded case, were effectively suppressed by trailing edge modifications, although mixing enhancement was not noticeable. From mixing and noise performance of nozzles with modified trailing edges, enhancing mixing through streamwise vortices seems an effective way to reduce mixing noise in the underexpanded flow regime. However, screech tones in the overespanded flow regime is well controlled or suppressed by making shock cells and/or spanwise large scale structures irregular and/or less organized by a proper selection of trailing edges. The noise field in the overexpanded flow regime was greatly affected by the symmetricity of the nozzle exit geometry. In the underexpanded flow regime, the effects of the symmetricity of the nozzle exit on mixing were negligible.

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Use of Rigid Scattering Body in the use of NAH based on the inverse BEM (역경계요소법에 근거한 근접 음향 홀로그래피에서 강체 산란체의 이용)

  • 김성일;정지훈;이정권
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.486-489
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    • 2004
  • The NAH based on the inverse BEM is used to reconstruct the source field, which is advantageous in dealing with the irregular source. In the implementation of this technique, a large number of pressure measurements is required because an over-determined pressure data set is required. These conditions accordingly cause the increase of measurement time and associated effort along with the error due to mal-positioning. The purpose of this study is to reduce such inconveniences: Instead of increasing the number of field pressure data, the number of transfer paths between the source and the receiver is increased by placing rigid scattering body in-between the source and receiver. For validating the usefulness and effectiveness of the method, the numerical analyses of interior problem are demonstrated. As a result, it is thought that the proposed method enables the measurement at smaller number of sensor positions and the monitoring of surface vibration with less experimental effects than before.

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A Study of Three-dimension Tissue Equivalent Compensator for 6MV X-Rays (6MV X-선에 대한 삼차원적 조직보상체의 연구)

  • Kim, Ok-Bae;Choi, Tae-Jin;Suh, Soo-Jhi
    • Radiation Oncology Journal
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    • v.7 no.1
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    • pp.133-140
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    • 1989
  • Three-dimension paraffin compensator was designed to construct the tissue equivalent compensator for irregular body contours and obiliques beam incidence. The ratio of compensator thickness to tissue deficit was depended on field size, depth and air gap because the scattered dose loss. The ratio of compensator-tissue was optimized 0.79, 0.73, 0.61 and 0.56 in 6MV x-rays as function of field size $4{\times}4$, $10{\times}10$, $20{\times}20$ and $30{\times}30cm^2$ respectively. in our study. Using this tissue equivalent compensator, it can be got 2% difference of dose at same mid-plane in phantom study.

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Prediction of Wave Transformation in the Kwangan Beach (광안해역에서의 파랑변형예측)

  • 박정철;김재중;김인철
    • Journal of Ocean Engineering and Technology
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    • v.15 no.2
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    • pp.6-10
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    • 2001
  • Water waves propagate over irregular bottom bathymetry are transformed by refraction, diffraction, shoaling, reflection etc. Principal factor of wave transform is bottom bathymetry, but in case of current field, current is another important factor which effect wave transformation. The governing equation of this study is develope as wave-current equation type to investigate the effect of wave-current interaction. It starts from Berkhoff's(1972) mild slope equation and is transformed to time-dependent hyperbolic type equation by using variational principal. Finally the governing equation is shown as a parabolic type equation by splitting method. This wave-current model was applied to the kwangan beach which is located at Pusan. The numerical simulation results of this model show the characteristics of wave transformation and flow pattern around the Kwangan beach fairly well.

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Determination of Magnetic Flux Distribution around the Salent Pole by means of the Fluid Mapper (Fluid mapper에 의한 철극형 전기기기의 자극 주변에서의 자속분포의 결정)

  • 우형주;고명삼
    • 전기의세계
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    • v.14 no.1
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    • pp.35-39
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    • 1965
  • Field problems are solved by a variety of methods. In the relatively small number of cases that are simiple enough, the mathematical attack may be the method of choice. But many field problems with irregular boundary condition must be handled by the use of the electrolitic tank analog, conducting paper or the fluid mapper analog for the purpose of effectiveness and convenience. The method of choice depends on the actual of the problems. There is no one best way to solve all problems. The following points have been described in this apepr, 1. Theoretical studies are made of the vector which is produced by leading the fluid flow vector by a right angle. 2. Curvilinear square method is described., 3. Determination on magnetic flux distribution and variation according to the magnitude of exciting currents.

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Domain formation characteristics during thermomagnetic recording for amorphous TbFe and TbFeCo alloy thin films

  • Kim, Soon-Gwang
    • Proceedings of the Optical Society of Korea Conference
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    • 1989.02a
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    • pp.235-241
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    • 1989
  • Static according tests were carried out on a series of amorphous TbFe thin films of various composition under a constant laser irradiation condition. Examination of recorded domain configurations by using polarizing microscope led to the categorization of domain characteristics into 3 distinctly different types; i.c., type A: circular domains with smooth boundaries, the size not sensitive to variation of bias field, type B: domains of irregular shape at low bias, the size increasing and the boundaries getting smoother and more circular with increasing bias field and type C: not recordable. Critical factor which distinguishes among each types was fond to be the relative magnitude of H and H of the film near T, regardless of constituent atomic species. Micromagnetical process of thermomagnetic recording cycle was analyzed scheniatically for each type.

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First Report of Anthracnose Disease Caused by Colletotrichum gloeosporioides in Stonecrop

  • Jeon, Chang Wook;Kwak, Youn-Sig
    • Journal of agriculture & life science
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    • v.50 no.5
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    • pp.251-255
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    • 2016
  • In year of 2013, anthracnose disease symptoms were observed on stem of stonecrop in a plant resource field, Southern Forest Resource Research Center, Jinju, South Korea. The disease symptoms were appeared 2-5 cm smudged irregular black spot color on the plant stems. Suspected pathogen was isolated from the lesion with surface sterilization method and identified it as Colletotrichum gloeosporioides by morphological characteristics and phylogenetic analyses. Artificially inoculated the isolated pathogen led to the similar disease symptom as originally observed in the field. The fungal pathogen was re-isolated from the inoculated lesion and it exhibited the same characteristics compared to the original isolate. This is the first report of anthracnose of stonecrop grown in open fields, caused by Colletotrichum gloeosporioides in Korea.

Accuracy Analysis of Topographic Survey Data for the Official Land Price Appraising (공시지가산정을 위한 지형·지세조사 자료의 정확도 분석)

  • Lee, Chang-Han;Sung, Chun-Ja
    • Journal of Cadastre & Land InformatiX
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    • v.48 no.1
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    • pp.153-167
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    • 2018
  • Despite many criticisms that topographic survey data for the official land price appraising collected annually using field survey method might be inaccurate, there is only few concrete research on it. This paper investigated whether the topographic survey data collected by a local government using field survey method is consistent with the data analyzed using the digital elevation model to examine its accuracy. The accuracy analysis indicated that 324 out of 1537 lots of land have inconsistent results which means the ratio of inconsistency is 17.36%. Among 11 areas studied, five had the inconsistency ratio above 20% while the worst one had 38.71%. The inconsistency ratio is generally higher for the rough terrain with irregular slope and high altitude while it is relatively lower for the terrain with smooth landform. The analysis results imply that there are limitations in investigating the topology by field survey method. Therefore, the official land price appraising policy should set precise criterion and change over to highly accurate geographic information analysis method to effectively and accurately examine topology, given the fact that the topology of the Republic of Korea has complicated features with irregular slope and altitude.

Field Technique of Non-Educated Constructors in Timber Structure of Korean-Style Secondary Station(Gong-So) -Focused on the Sin-Sung and Su-Bun Secondary Stations- (한옥 공소의 목구조 방식에 나타난 민간 기술자의 현장기법 -천주교 신성공소와 장수천주교회 수분공소를 중심으로-)

  • Park, Kwang-Hyun;Kim, Tai-Young
    • Journal of the Korean Institute of Rural Architecture
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    • v.12 no.1
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    • pp.49-56
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    • 2010
  • This paper is aimed to clarify field technique of non-educated constructors in timber structure of korean-style secondary station(Gong-So) on the annex of catholic church. The main object of this study is Sin-Sung and Su-Bun secondary stations which post-lintel structure was 2high columns(Go-Ju) 5beams(Ryang) in Jeon-Buk area of Korea. We reached the following conclusion. Firstly, these secondary stations are required a lots of space for number of persons with the introduction of basilica plane. These plans have different intervals in the layout. Secondly, they constructed the holy space by using high columns(Nae-Jin-Go-Ju). The former problems of plan layout are sloved by reinforcement and replacement eaves and rafter of logitudinal. Thirdly, the elements showed the natural feature such as irregular wooden floor, arch-type head pentrating tie and a ceiling. In the end, we knew that non-educated constructor had found a way in the problem for accepting unreasonable work.