• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.214-215
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• 2011

RF 플라즈마의 경우 일반적인 싱글 랑뮤어 프루브를 사용하여 I-V 파형을 구하는 경우에, 우리는 시평균한 값만을 구할 수 있다. 일반적인 플라즈마 반응 챔버의 구조상, 양 전극의 크기가 다르기 때문에, 시간에 따라 진동하는 플라즈마 포텐셜의 형태는 정확한 사인파의 형태가 아니다. 그렇기 때문에 플라즈마 포텐셜에 따라서 진동하는 데이터를 시평균한 값에는 DC 오프셋 성분이 나타난다. 이러한 DC 오프셋값은 랑뮤어 프루브를 통한 플라즈마 포텐셜 측정시에 오차로 나타난다. 우리는 DC 오프셋에 의한 에러값을 보정하기 위해 멀티 프루브를 사용할 수 있다. 가장 흔하게 쓰이는 듀얼 랑뮤어 프루브의 경우를 살펴보면, 내부의 전원이 플로팅되어 있으며 전압인가를 위한 회로 또한 접지에서 절연되어 있기 때문에, 플라즈마 포텐셜이 시간에 따라 흔들려도 전체적인 전위가 플라즈마 포텐셜과 함께 움직이기 때문에, 앞에서 말한 DC 오프셋에 의한 오차를 줄일 수있다는 장점이 있다. 그러나, 이를 위하여는 회로의 절대적인 플로팅이 필요하지만 실제 듀얼 랑뮤어 프루브의 전원 회로를 구현시에는, 트랜스포머 등을 사용하여 회로를 절연시켜도 회로에 기생적으로 발생하는 콘덴서 성분 때문에 플로팅에 영향을 받을 수 있다. 또한 양극과 음극 사이의 내부 임피던스가 다르게 나타난다. 실제로 기존의 듀얼 랑뮤어를 가지고 RF 플라즈마를 측정할 때에, 듀얼 랑뮤어 프루브의 두 팁 간에 서로 다른 전압-전류 파형이 나타나곤 한다. 이러한 두 팁간의 전압-전류 파형의 차이는 두 팁이 물리적으로 완전히 동일한 구조를 가질 수 없기 때문에 발생 하기도 하지만, 위에서 밝힌 원인에 의해서도 발생한다. 이로 인하여 듀얼 랑뮤어 프루브에 의한 I-V 파형은 이론 상 원점을 대칭으로 한 기함수의 형태이어야 하는데, 실제 측정 결과를 보면 이러한 대칭 형태의 모양을 보기 힘들다. 우리는 이에 이를 보정하기 위하여 위상이 180도 차이가 나는 두 개의 삼각파 발생 전원을 각각 듀얼 랑뮤어 프루브의 양 팁에 인가하여 두 팁 간의 내부 저항과 기생 임피던스 등을 일치시킨 프루브를 디자인하였으며 이 프루브를 이용한 실험에서, 비교적 완벽하게 원점에 대하여 대칭하는 I-V 커브를 구할 수 있었다. 이에 이 논문에서는 새로운 회로와 이 회로로 이루어진 듀얼 랑뮤어 프루브를 사용하여 플라즈마를 진단하는 방법에 대하여 기술한다.

• Journal of the Korean Chemical Society
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• v.46 no.6
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• pp.545-549
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• 2002

Many theories for polymeric liquids are based on the concepts of cell, hole, free volume or lattice etc. In the theories, van der Waals potential, Lennard-Jones 6-12 potential and their modified potentials are commonly used.In this work, Mie(p, 6) potential was applied to the Continuous Lattice Fluid Theory (which extends the discrete lattices of Lattice Fluid Theory to classically continuous lattices) and Dee-Walsch's Cell Theory (which modifies Flory's Equa-tion of State Theory). Both of them are known to be successful theories for polymeric liquids. Thus, PVT values chang-ing with p (the exponent in the repulsion potential) were calculated and compared with experimental values. And, calculated values of Lattice Fluid Theory, Flory's Equation of State Theory and Cho-Sanchez Theory using pertubation method were also compared. Through the calculated results, van der Waals potential, Lennard-Jones 6-12 potential and Mie(p, 6) potential for polymeric liquids were compared with each other.

• Journal of Bio-Environment Control
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• v.9 no.2
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• pp.94-100
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• 2000

This study was conducted to investigate the changes of electric potentials of leaf surface induced by environmental stimuli in plant. The values of electric potentials varied with different intervals of light on and off, and light qualities and moreover, their changes were also varied according to the time of a day. Additionally, stimuli such as candle light, wind, or 5$^{\circ}C$ cool water spray also evoked considerable changes in leaf surface electric potentials and their signal patterns varied with species of plants tested. In frequency analysis of electric potentials, the distribution values by FFT were highest in 1-10 Hz frequency zone by the majority of stimuli. These results suggested that changes in leaf surface electric potentials depended upon plant species even though stimulus was the same and vice versa.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.69-76
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• 1990

To find out whether isotropic magnetic bubble propagation can be achived by changing magnetostriction coefficients, bias margins and bubble collapse fields of $2.5{\mu}m$ period "diamond" bubble propagation tracks were measured which were fabricated on three magnetic garnet thin films with nearly isotropic magnetostriction coefficients (${\lambda}111{\simeq}{\lambda}100$). The results showed substantially isotropic bubble propagation in "super","good" and "bad" tracks for all three garnet films. From the bubble collapse fields, the bubble potential well depths vs. the direction of the in-plane rotating magnetic fields were plotted. The results showed that substantial differances in the potential well shapes exist for the three "good," "bad" and "super" tracks when ${\Delta}(=({\lambda}111-{\lambda}100)/{\lambda}100)$ was 0.5 (film AK92). However, the differences were minimal when ${\Delta}$ were 0.3 (film Aka8) or 0.1 (film AKb1). In other words, the bubble potential wells were nearly isotropic. The above two measurements indicate that nearly isotropic bubble propagation can be achieved when B is between 0.1 and 0.3.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.415-420
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• 2020

Crowd flows occur in metropolitan railway transit stations, terminals, multiple buildings, and stadiums and are important in ensuring the safety as well as smooth flow of pedestrians in these facilities. In this study, the author developed a new computational analysis method for crowd flow dynamics and applied it to models of transit connecting paths. Using the analysis method, the potential value of the exit was assigned the smallest value, and the potential value of the surrounding grids gradually increased to form the overall potential map. A pathline map was then constructed by determining the direction vector from the grid with large potential value to the grid and small potential. These pathlines indicate basic routes of passenger flow. In all models of the analysis object, the pedestrians did not move to the first predicted shortest path but instead moved using alternative paths that changed depending on the situation. Even in bottlenecks in which pedestrians in both directions encountered each other, walking became much smoother if the entry time difference was dispersed. The results of the analysis show that a method for reducing congestion could be developed through software analysis such as passenger flow analysis without requiring hardware improvement work at the railway station.

• Journal of the Korean earth science society
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• v.35 no.6
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• pp.412-421
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• 2014

In order to develop an effective mineral exploration technique, this study was carried out about the potential mapping of Gagok mine. The deposit model of Gagok mine is widely known. Based on the deposit model, we constructed mining indicator indices using related igneous rocks, faults, and carbonate rocks. By analyzing the spatial correlation between ore and indicator index structures, we decided the weighting values of indices according to the distance from the index structure. The 3D potential mapping was performed using 3D geological model and geological indices. The analyzed potential map verified that the locations and patterns of high potential regions of the results were well matched with those of the known ore bodies. Using the potential mapping results, we could effectively predict the location of a high potential area that has similar geological settings with ore.

• Journal of the Korean Wood Science and Technology
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• v.28 no.1
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• pp.55-64
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• 2000

Culture maturity assessment can be used to control fruiting body flush timing. Culture maturity of sawdust-based substrate was evaluated by using oak mushroom, (Lentinula edodes (Berk.) Pegler). The influence of substrate water potential (${\psi}$) on the growth and fruiting of three genotypes of L. edodes was also investigated. Glucosamine content revealed a peak at the fruiting body senescent stage. Glucosamine increased steadily to the sporophore senescent stage, and sharply declined at crop treatment. Lipid phosphate and ergosterol contents peaked at pinning and button break stages, respectively. Therefore lipid phosphate and ergosterol contents would be considered as the convenient measurement for judging culture maturity and fruiting potentials. The substrate pH values before inoculation and on the fruiting stage were varied from 6.3 to 4.0. This pH changes were detected as changes in color from bluish purple to yellow by direct bromphenol blue(BPB) spraying, and shown a good correlation with fruit body yield of the 1 st flush. Concerning water potential of the cultures, a slight reduction of water potential, -0.5MPa, stimulated mycelial and colony growths on liquid, agar and sawdust-based substrates. The water potential of well-colonized matured substrate was -0.7MPa and -4.0MPa, before and after the fruiting, respectively. Excellent water providing capacity (higher ${\psi}$) is expected to well-matured cultures with a high density of mycelial colonization. Also, the substrate water potential significantly affected by the interaction between genotypes and spawn run time.

• 한국지구물리탐사학회:학술대회논문집
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• 2010.10a
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• pp.155-156
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• 2010

포텐셜 자료의 해석을 위해서는 상하향 연속을 이용하는 경우가 많다. 빠른 계산과 다양한 적용성 때문에 FFT(Fast Fourier Transform)을 이용한 상하향 연속을 주로 사용하는데, FFT를 적용하기 위해서는 격자망 형태로 얻어진 자료가 필요하다. 현장 중자력 자료는 보통 산발적(scattered)으로 얻어지기 때문에 FFT를 수행하기 위하여 격자망 자료로 변환하는 격자화(gridding) 과정에서 계산적인 오차가 발생한다. 반면 등가샘(equivalent source) 방법은 주어진 자료에 맞는 가상의 샘(source)들의 조합을 생성하고, 구해진 샘들의 조합으로부터 임의의 영역에서 필드값을 구하므로 격자화 과정이 필요없다. 이 연구의 목적은 등가샘 방법의 필요성을 보이고 여러 가지 등가샘 알고리즘을 비교분석하고 현장 자료에 사용하기 적합한 등가샘 방법들을 보여주는데 있다. 그림 1에서 보듯이 FFT를 사용한 상향 연속은 FFT 이론상 전 영역에 대한 적분이 필요하나 현장에서는 일부분의 자료만을 획득할 수 있으므로 상향 연속에서 정확한 자력값으로 연속을 수행하는 것은 불가능하다. 그러나 주어진 값들로 등가샘을 구성하여 상향 연속을수행한 결과는 상대적으로 보다 정확한 해에 도달한다. 또한 등가샘 방법을 이용한 연속의 장점은 그림 2와 같이 얻어진 자료의 높이가 서로 다른 자료를 주어진 높이로 연속을수행할 수 있다는 점이다. 또한 한번 등가샘들을 구성하면 이를 이용하여 격자화, 필터링 등을 해석을 위한 기초 자료처리에 적용할 수 있다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.4
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• pp.233-237
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• 2003

This study was conducted to provide a rational forest management method for a natural oak (Quercus variavilis) forest stand in the central part of South Korea based on characteristics of growth and water relation parameters. Average volume per hectare was 175.1 ㎥ in the study site of oak stands. Basal area and volume of each direction appeared to increase as the slope direction moves from north to south, but annual mean increment and periodic annual increment of DBH for 10 years showed the lowest value at the southern aspect. Maximum water potentials measured between 12 and 14 o'clock were analyzed by direction and elevation in the oak stands. Water potential of oak decreased as the slope changed from the north to the south aspect and water potential increased at lower elevations. Soil water content for the oak stands tended to decrease as the aspect shifted from north to south. Water potential and soil moisture content were highly correlated. It appears that oaks have a higher moisture requirement at the southern aspect, because of stand density related to intraspecific competition.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.1
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• pp.18-23
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• 2004

This study was conducted to provide a national forest management method for natural Pinus densiflora forest stands in central South Korea based on growth characteristics and water relations. Average stand volume per hectare was 259.3㎥ in the pine study site. Basal area, volume, annual mean increment and periodic annual increment of DBH for 10 years at each slope aspect appeared to decrease as the aspect shifts from north to south. Stems per hectare showed the lowest value at the northern aspect. Maximum water potentials measured between 12 and 14 o'clock were analyzed by aspect and elevation. Water potential of pine decreased as the aspect changed from north to south, and water potential increased at lower elevations. Soil water content for the pine stands tended to decrease as the aspect shifted from north to south. Water potential and soil moisture content were highly correlated. Soil water deficits indicate that pines have a higher moisture requirement on the ridge and the southern aspect.