• Journal of Advanced Marine Engineering and Technology
• /
• 제17권4호
• /
• pp.20-27
• /
• 1993

Emulsified oily wastewater is generally hard to treat in separating oil and water by conventional separators. In this paper the magnetohydrodynamic water treatment device was used to separate oil from emulsified oily wastewater which contained high conductivity. The emulsified oil removal rates and economic ranges of oil separation at various factors were investigated to confirm the influence of the magnetic field in MHD water treatment device according to the characteristics of emulsion brake. Experimental results proved that the oil removal rates were proportional to Lorentz force which depends on the intensity of magnetic field, conductivity and velocity of wastewater.

• 대한기계학회논문집A
• /
• 제30권2호
• /
• pp.179-186
• /
• 2006

Dielectrophoresis has received considerable attention for separating nanotubes according to electronic types. Here we examine the effects of surface conductivity of semiconducting single-walled carbon nanotubes (SWNT), induced by ionic surfactants, on the sign of dielectrophoretic force. The crossover frequency of semiconducting SWNT increases rapidly as the conductivity ratio between the particle and medium increases, leading to an incomplete separation of ionic surfactant suspended SWNT at an electric field frequency of 10 MHz. The surface charge of SWNT is neutralized by an equimolar mixture of anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant cetyltrimenthylammonium bromide (CTAB), resulting in negative dielectrophoresis of semiconducting species at 10 MHz. A comparative Raman spectroscopy study shows a nearly complete separation of metallic SWNT.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집A
• /
• pp.848-853
• /
• 2001

A study about the shrink fits of rotor and retaining ring in generator was performed for the cases of three radial interference. The shrink-fitted retaining ring used to restrain the end turns of the winded coils in the rotor against centrifugal force requires very careful attention during design and manufacture because it has traditionally been the highest-stressed component of the generator. The contact pressures and residual stresses were obtained by the finite element analysis for each radial interference at zero, 100% rated, and 120% rated speeds, respectively. The results of analysis show that the radial interference in use needs to be increased carefully.

• 전기학회논문지
• /
• 제62권6호
• /
• pp.825-832
• /
• 2013

In this study, Independent Component Analysis (ICA) algorithms are suggested to extract the original ECG part from the mixed signal contaminated with the unwanted frequency components and especially 60Hz power line disturbances. With this aim, we implement a novel method to suppress the baseline-wandering disturbances and power line artefacts contained in patch-electrodes sensory ECG data by separating the unmixed signal with finding the optimal weight W based on Kurtosis value. With applying brutal force and gradient ascent searching algorithm to find W, we can conclude that the unwanted frequency components especially in the ambulatory ECG data can be eliminated by Independent Component Analysis.

• Journal of Magnetics
• /
• 제22권2호
• /
• pp.266-274
• /
• 2017

In this paper, torques of two motors are compared by Finite Element Analysis (FEA). One has a symmetric rotor structure and the other has an asymmetric rotor structure. The comparison shows that the asymmetric rotor structured motor has reduced torque ripple compared to the symmetric. The torque of the compared motor models was analyzed by separating into magnetic torque and reluctance torque. Through the analysis of torque component separated, it is shown that the magnetic torque and the reluctance torque compensate each other in the motor with the asymmetric structure rotor. Here "compensate" means decrementing the effect of one or more harmonics. It is shown how this compensation appears between the magnetic torque and the reluctance torque by looking into back electro motive force (emf) and the relative permeability distribution of rotor core.

• 대한기계학회논문집
• /
• 제15권1호
• /
• pp.145-153
• /
• 1991

본 연구에서는 Toh가 개발하여 stretchforming에 응용한 강소성 대변형 이론 을 압연문제에 적용하여 강소성 대변형 유한요소 프로그램을 개발하는데 있다.

• 시큐리티연구
• /
• 제50호
• /
• pp.307-337
• /
• 2017

집회의 자유는 헌법에서 보장하고 있는 기본권적 자유이다. 우리의 현실을 보면 집회의 자유는 경찰의 관리통제 하에 있을 때에만 보장되고, 그렇지 않을 때는 진압해야 할 대상으로 인식되고 있다. 심지어 경찰은 '깨진 유리창 이론(broken window theory)'을 거론하면서 조그만 불법이 심각한 불법․폭력시위로 변질될 수 있다는 이유로 집회의 평화성 보다는 '준법'여부에 집착하고 있는 듯한 태도를 보여주고 있다. 이러한 태도는 집회에 참여하는 시민을 진압해야 할 대상으로 내몰게 되는 결과를 초래하고 있다. 이 글은 최근 문제되고 있는 경찰물리력 사용수단으로서 차벽과 물포를 중심으로 물리력 사용요건과 현황을 분석하고, 그 개선방안을 제시하였다. 우선, 차벽의 설치는 집회장소를 항의의 대상으로부터 분리시킴으로써 집회가 갖는 본질적인 소통의 기능을 차단하고 있다. 따라서 차벽설치는 불법행위에 직면하여 예방을 위한 경고에도 불구하고 차벽설치 이외 다른 방법으로는 '사람의 생명 신체에 위해를 끼치거나 재산에 중대한 손해를 끼칠 우려가 있는 긴급한 경우'에 한하여 허용되어야 할 것이다. 이러한 긴급성이 없다면 차벽은 사전예방적 차원뿐만 아니라 사후예방적 차원에서도 허용되어서는 안된다. 물포는 사람의 생명․신체에 위해를 가할 우려가 있는 경찰장비로서 기본권의 중대한 제한을 가져오는 강제조치이다. 따라서 사람의 신체에 중대한 위험을 초래할 수 있는 조준 직사살수는 원칙적으로 금지되어야 한다. 다만 그 위험성을 고려하여 타인의 법익이나 공공의 안녕질서에 직접적인 위험이 '명백하게 초래'된 경우에 한하여 다른 대안이 없는 경우에 보충적으로 사용하여야 한다. 아울러 그 사용기준 등에 대해서는 물포가 위해성 경찰장비인 점을 고려하여 법률로 명시해야 한다.

• 대한치과교정학회지
• /
• 제13권2호
• /
• pp.147-154
• /
• 1983

This experiment was performed to study the effect of $PGE_2$ on the bone resorption at the tooth movement by orthodontic force. The experimental animals were the Sprague-Dawley strain rats. The orthodontic force was applied by the insertion of separating clamp made of 0.014' (0.356mm) wire to the interproximal site between the 2nd and the 3rd upper right molars. In experiment I, $0.2{\mu}g,\;0.4{\mu}g,\;0.8{\mu}g,\;and\;1.0{\mu}g\;PGE_2$ were locally injected at the submucosa near the 2nd molar of the maxilla each. The effect was detected by the count of the number of osteoclasts appeared at the compressed surface of interradicular bone. In experiment II, 1.0 mg/kg indomethacin (a specificc inhibitor of prostaglandin synthetas.) was subcutaneously injected. The effect was examined by the count of the number of cateoclasts appeared at the compressed surface of interradicular bone. The obtained results were follows; 1. The number of osteoclasts on the compressed surface of the interradicular bone increased in proportion to the increased dosage of $PGE_2$ administered. The number of osteoclasts increased significantly at the administration of $0.8{\mu}g\;and\;1.0{\mu}g\;PGE_2$ in contrast to the control (P<0.05). 2. The administration of 1.0 mg/kg indomethacin decreased the number of osteoclasts at the compressed bony surface significantly (P<0.01).

• 항공우주정책ㆍ법학회지
• /
• 제26권2호
• /
• pp.69-100
• /
• 2011

현행 '항공법'의 벌칙조항 및 '항공안전 및 보안에 관한 법률'은 항공교통의 안전이 지상 및 해상교통과 비교해볼 때 상대적으로 운항안전체계의 영향을 많이 받고 있고, 범죄의 대상이 될 경우 항공기에 탑승한 승객 및 승무원의 안전만을 위협하는 것이 아니라, 항공기 그 자체가 지상의 인원과 재산에 막대한 피해를 입힐 수 있는 가능성을 고려하여 입법되었다고 할 수 있다. 그러나 현행법을 분석해 보면, 일부 규정의 경우 적용대상 및 행위방법이 지나치게 광범위하여 구체성을 상실하고 있으며, 그 적용대상 및 행위방법을 개별화하지 않고 일률적으로 지나치게 높은 법정형을 규정하고 있는 경우가 다수이고, 입법상의 몇가지 중대한 흠결이 존재하고 있으며, 입법 체계상 법률 상호간의 적용영역에서도 문제의 소지가 있다. 이와 같은 항공관련 형사특별법의 입법상의 문제는 그 입법과정에 형사법 전문가 보다는, 항공안전전문가나 정책입안자의 참여가 더 적극적으로 이루어진 결과이거나, 전문가그룹 간의 상호 의사소통이 충분히 이루어지지 않은 결과로 보인다.

• 상하수도학회지
• /
• 제32권6호
• /
• pp.479-485
• /
• 2018

Large amounts of oily wastewater discharged from various industrial operations (petroleum refining, machinery industries and chemical industries) cause serious pollution in the aquatic environment. Although dissolved air flotation (DAF) separating oil pollutants using microbubbles represents current practice, bubble size cannot be selectively controlled, and lots of power is required to generate microbubbles. Therefore, to investigate performance of the DAF process, this study examined the distribution of different sizes of microbubbles resulting from changes in physical shear force via modifying shapes of a slit-nozzle without an additional power supply. Three types of slit-nozzles (different angle, shape and length of the slit-nozzle) were used to analyze the distribution of bubble size. At a slit angle of $60^{\circ}$, shear force was 4.29 times higher than a conventional slit, and particle size distribution (PSD) in the range between 2 and $20{\mu}m$ more than doubled. Treatment efficiency of synthetic oily wastewater through the coagulation-DAF process achieved 90% removal of COD by injecting $FeCl_3$ and PACl of 250 mg/L and 100 mg/L, respectively, and the same performance resulted using $FeCl_3$ of 200 mg/L and PACl of 80 mg/L employing a slit-nozzle angle of $60^{\circ}$. This study shows that a coagulation-DAF process using a modified slit-nozzle can improve the pre-treatment of oily wastewater.