• 한국축산시설환경학회지
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• 제14권3호
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• pp.149-158
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• 2008

본 시험은 젖소농가에서 보유하고 있는 여러가지 형태의 착유시스템에 대하여 계절별 세척수의 발생량과 이화학적 특성을 알아보고자 바켓식, 파이프라인식, 텐덤식, 헤링본식 등 착유시스템 유형별로 각각 3농가를 선정하여 계절별로 조사를 실시하였으며, 그 결과는 다음과 같다. 1. 착유시스템 유형별 세척수 발생량은 텐덤식과 헤링본식에서 많았으며 바켓식이 적었다 (P<0.05). 2. 착유작업별 세척수 발생량은 착유기 세척에 가장 많은 량의 세척수를 사용하였으며 여름철의 경우 텐덤식 $398.8{\ell}$, 헤링본식 $407.7{\ell}$가 다른 착유시스템보다 많은 세척수를 사용하였다 (p<0.05). 3. 착유과정에서 발생하는 세척수 발생량을 조사한 결과, 평균 $15.4{\ell}$/두였으며, 계절별로는 여름이 $16.4{\ell}$로 가장 많은 세척수가 발생되었다. 4. 착유과정에서 발생하는 세척수의 $BOD_5$는 착유실 세척시 발생하는 세척수가 $906.4mg/\ell$로 가장 높았으며, 유두 세척시 가장 낮은 $212.4mg/\ell$로 나타났다. COD, SS 등도 착유실 바닥세척시 가장 높은 경향을 보였다. 5. 세척수의 이화학적 특성은 pH는 $7.3{\sim}8.2$의 범위로 착유작업 단계에 따라 차이를 나타내었으며, 착유작업 후 착유실 외부로 흘러나오는 배출수의 $BOD_5$, COD, SS, T-N, T-P는 각각 731.2, 479.0, 751.6, 79.1, $14.7mg/\ell$였다. 이상의 시험결과를 종합해 보면 착유시스템 유형별 세척수 발생량은 바켓식, 파이프 라인식, 텐덤식 및 헤링본식이 각각 143.9, 487.9, 914.0, $856.7{\ell}$로 조사되었으며, 착유과정에서 발생하는 세척수량은 착유우 두당 $15.4{\ell}$로 착유시스템 유형 및 착유우 사육두수에 따라 낙농가도 농가실정에 맞는 세척수 처리시설 및 용량을 확보해야 할 것으로 판단된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2273-2278
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• 2007

Brazed Plate Heat Exchanger (BPHE) is a type of compact plate heat exchanger with parallel corrugated plates which are brazed together in series. Each plate hascorrugation called herringbone pattern. Inside a BPHE, hot fluid and cold fluid alternate its flow direction to establish counter current flow configuration. Two-phase flow heat transfer and pressure drop of R-22 in BPHE were experimentally measured in this study. In the present experiments, single-phase region and two-phase region coexist in a BPHE. Therefore, the inside of a BPHE have to be divided into single phase region and two phase region and analyzed accordingly. The results from the single phase flow analysis are then extended to the two phase flow analysis to correlate the condensation and evaporation heat transfer and pressure drop for the refrigerant R-22 in the BPHEs. Previous models for two- phase friction factor have been compared with the present experimental results.

• Toxicological Research
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• 제27권3호
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• pp.149-152
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• 2011

We describe here a multicentric spontaneous malignant schwannoma obtained from one male F344 rat, and this animal was the subject of a carcinogenicity study for which it was treated with diisodecyl phthalate. The animal of the control group not treated with diisodecyl phthalate showed dyspnea and severe lordosis. On the necropsy, two tan, firm, encapsulated masses were observed in the subcutis of the lumbosacral region and the left inguinal region of the abdominal cavity, respectively; the masses were $25{\times}17{\times}8$ mm and $16{\times}14{\times}8$ mm in size, respectively. Histologically, the tumor consisted of spindle and pleomorphic cells that grew in various patterns, that was, sweeping fascicles and herringbone and local organoid patterns. The pleomorphic neoplastic cells had more than two nuclei. Additionally, the diagnosis of malignant schwannoma was confirmed by the immune reactivity of the tumor cells for S-100 protein.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.77-83
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• 2007

This paper presents numerical and experimental works for simultaneous pumping and mixing small liquid using asymmetric microelectrode arrays, based on AC electroosmotic flows. To this end, four arrangements of electrode pairs were considered with diagonal/herringbone shapes. Numerical simulations were made of three-dimensional geometries by using the linear theory. The results indicated that the helical flow motions induced by the electrode arrays play a significant role in the mixing enhancement. The pumping performance was influenced by the slip velocity at the center region of the channel compared to that near the side walls. To validate the numerical predictions, the microfluidic devices were made through MEMS. The flow rate was obtained by using micro PIV, increasing the applied frequency. The electrolyte was potassium chloride solution. The flow patterns above electrodes were visualized to see lateral flow for mixing. The experimental results showed good agreements with the numerical predictions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1758-1760
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• 2008

Under typical operating conditions, flows in microfluidic devices are laminar and molecular diffusion across the channels is slow, which makes an efficient mixing in microfluidic devices difficult to achieve. The mechanism to achieve effective mixing in laminar flows is that of repetitive stretching and folding. Essential is to generate spatially periodic flows with crossing cross sectional streamlines. A mapping method is employed to analyze mixing in micromixers, enabling us to investigate the progress of mixing both qualitatively and quantitatively. The progress of mixing is characterized by a measure of mixing, called the discrete intensity of segregation. The mapping method is applied to mixing in such micromixers as the staggered herringbone mixer, the barrier embedded micromixer, and the three-dimensional serpentine channel to demonstrate the capability of the numerical scheme to tackle general mixing problems in microfluidic devices.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.906-910
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• 2003

This paper numerically analyzes the dynamic characteristics of a spindle system supported by two identical journal bearings considering bearing span that has dynamic load due to its mass unbalance. The Reynolds equation is transformed to solve a herringbone grooved journal bearing. The Reynolds equations are solved using FEM in order to calculate the pressure distribution in a fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors, such as whirl radius or angular displacement of a rotor, are determined by solving its nonlinear equations of motion with the Runge-Kutta method. This research shows that the same bearing spans of upper and lower journal bearings produce the minimum runout and friction torque of a spindle system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1076-1082
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• 2003

As functional requirement of massive digital information storage devices are on a trend for the higher data transfer rate and lower cost, many different technical efforts are being tested and implemented in the industry. FDB(Fluid Dynamic Soaring) is one of the major breakthroughs in rotor design in terms of TMR budget. Although FDB analysis based on Reynolds' equation is well established and popularly being used for DB design especially for the estimation of bearing stiffness, there are obvious limitations in the approach due to the inherent assumptions. A generalized analysis tool employing the full Navier-Stokes equation and the energy balance is to be beneficial for detailed FDB design In this publication, an efficient geometry modeling method is presented that provides fully integrated inputs for general FVM/FDM codes. By virtue of the flexibility of the presented method, many different detailed FDB design and analysis are carried over with ease.

• 한국재료학회지
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• 제27권9호
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• pp.484-488
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• 2017

In the present study, domain evolution processes of a near-morphotropic PZT ceramic during poling was studied using vertical piezoresponse force microscopy (PFM). To perform macroscopic poling in bulk polycrystalline PZT, poling was carried out in a stepwise fashion, and PFM scan was performed after unloading the electric field. To identify the crystallographic orientation and planes for the observed non-$180^{\circ}$ domain walls in the PFM images, compatibility theory and electron backscatter diffraction (EBSD) were used in conjunction with PFM. Accurate registration between PFM and the EBSD image quality map was carried out by mapping several grains on the sample surface. A herringbone-like domain pattern consisting of two sets of lamellae was observed; this structure evolved into a single set of lamellae during the stepwise poling process. The mechanism underlying the observed domain evolution process was interpreted as showing that the growth of lamellae is determined by the potential energy associated with polarization and an externally applied electric field.

• Tribology and Lubricants
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• 제18권5호
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• pp.364-370
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• 2002

In this paper, numerical analyses were undertaken to calculate the static and dynamic performances of step-pocket, inward pumping spiral grooved, outward pumping spiral grooved and herringbone grooved bearings. For each bearing, optimal values for various design parameters were obtained to maximize the load capacity and the stiffness and bearing performances were calculated. The optimized performances of these bearings were compared to conclude that the performance of step-pocket bearing is better than the other bearings.

• 한국소음진동공학회논문집
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• 제14권9호
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• pp.779-784
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• 2004

This paper numerically analyzes the dynamic characteristics of a spindle system supported by two identical journal bearingsconsidering bearing span that has dynamic load due to its mass unbalance. The Reynolds equation is transformed to solve a herringbone grooved journal bearing. The Reynolds equations are solved using FEM in order to calculate the pressure distribution in a fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors, such as whirl radius or angular displacement of a rotor, are determined by solving its nonlinear equations of motion with the Runge-Kutta method. This research shows that the same bearing spans of upper and lower journal bearings produce the minimum runout and friction torque of a spindle system.