The research aimed to develop a high-efficiency plate-type heat exchanger for exhaust gas using computational fluid dynamics (CFD) thermal analysis based on the plate shape, and to identify the optimal shape. Following this, a water/air plate heat exchanger was manufactured, and its characteristics were studied experimentally. As the Re number increases on the gas (or air) side, the heat transfer rate increases significantly, whereas an increase in the Re number on the water side leads to a smaller increase in heat transfer. This is attributed to the larger convective heat resistance on the gas side, causing a substantial reduction in gas-side heat resistance as gas velocity increases, resulting in a considerable overall reduction in heat resistance. The fluid flow pressure drop showed similar results between the CFD calculations and experimental outcomes.

In this paper, the control technique of the stepping motor using back electromotive force(B-EMF) without encoder is investigated. The stepping motor generally uses the rotary encoder to detect the rotor position. Since this method increases the cost and the motor configuration size, the new closed-loop control method applied for the B-EMF was implemented by using current detect circuit, AD-converter, and micro controller unit(MCU). The contorl loop of stepping motor became very simplified. The current change of stepping motor measured by the amplifier was measured and analyzed, when the missing step is occurred. Based on the data from current feedback, position errors were compensated and confirmed by using AD-converter.

In this paper investigated the without encoder drive for stepping motor using back electromotive force(B-EMF). In generally stepping motor should be rotary encoder to rotor position, the rotary encoder is adopted to detect the position. But in this way increase cost and volume. This paper propose B-EMF & closed-loop method was implemented using current detect circuit, AD-converter and MCU(micro controller unit). So that stepping motor environment is very simplify. The current of stepping motor was measured by using amplifier. The change of current was measured and analyzed, when the missing step occurred. Based on data from current feedback, position errors were compensated and it was confirmed by using AD-converter.

The regeneration of periodontium is the goal of periodontal therapy. Many periodontologists try to achieve this goal by using guided tissue regeneration(GTR) method. However, these procedures always include several disadvantages. Recombinant human bone morphogenetic protein-2 (rhBMP-2) stimulated ectopic bone formation when it was implanted in rat muscles with insoluble bone matrix by differentiating muscle cells into chondrocytes and osteoblasts. The purpose of this study was to evaluate the osteoinductive potential of the mixture of rhBMP-2 (5 μg/ml) and heparin (0.25 or 25 μg/ml ) at the critically sized rabbit calvarial defects. And this study aimed to reveal that heparin also acts to enhance the bone forming activity of rhBMP-2. The 12 rabbits (4-month-old; NewZealand White) were used in the present study. 5 μg/ml of rhBMP-2 and 0, 0.25 or 25 μg/ml of heparin were mixed and blotted into anorganic bovine bone and filled cranial defects. The animals were sacrificed following a time schedule (1, 3, and 6 weeks). Sections were made in 7 μm thicknesses, stained with H&E and Masson's trichrome method, and examined under a light microscope. The differences among each obtained percent value were evaluated by one-way analysis of variance. A p value of p<0.05 was considered statistically significant and an ANOVA test was performed to verify significant differences. To adjust for multiple comparisons when one-way analysis of variance showed a significant difference between groups (p<0.05), Scheffe`s post hoc test was used to identify which group differences accounted for the significant p-value. In control group, osteoinduction was not outstanding, however, in experimental groups, osteoinduction was significantly outstanding, and as the concentration of heparin mixed with rhBMP-2 increased, osteoinduction was increased. Mixtures of rhBMP-2 and heparin affect bone formation at initial bone formation, but that effect disappeared following a time lapse.

Bone morphogenetic proteins (BMPs) are known to promote osteogenesis, and clinical trials are currently underway evaluating the ability of BMPs to promote bone formation in grafting procedures and fracture healing. Some studies, have independently reported that sulfated polysaccharides particularly heparin, enhance the osteoblastic differentiation induced by BMPs in vitro, and another study demonstrated that heparin enhanced the bone formation induced by BMP‐2 in vivo. This study was performed to examine adipose stem cell responses to rhBMP‐2 alone and rhBMP‐2 with heparin at 0.25, and 25 μg/㎖ concentrations, respectively, in culture media. Adipose stem cells were cultured for 2, 4, and 8 days toward the osteoblastic differentiation in rhBMP‐2 alone and rhBMP‐2 with heparin at 0.25, and 25 μg/㎖ concentrations, respectively, in culture media. Verification of the stem cell lineage was performed in two ways. The first method was a continuous sequential culture until 5th generation. The second method was using monoclonal antibodies for STRO‐1 and CD 90. Naphthol AS phosphate‐fast blue BB staining for alkaline phosphatase was used for verifying osteoblastic differentiation because Alkaline phosphatase activity had been used as an osteoblastic differentiation marker and degree of osteoblastic activity. Alizarin red staining was also used as an osteoblastic differentiation marker because it quantifies the calcium levels in cells or tissues. During the 5th generation culture, cultured cells actively proliferated, and these cultured cells showed a positive reaction to STRO‐1 and CD90 cell surface molecules. Naphthol AS phosphate‐fast blue BB staining and Alizarin red staining were positive in most samples of each group at 2, and 4 days and positive reaction was proportioned to degree of morphological differentiation. In the concentration of 25 μg/ml of heparin, the ALP activity was highest at the 2nd day in the culture, and then the activities of ALP were decreased significantly at 4, and 8 days. The ALP activity was greatest at the 4th day of the culture, and then decreased significantly at the 8th day in 0 μ g/ml and 0.25 μg/ml of heparin concentrations, Adipose stem cells could be differentiated in rhBMP‐2 in culture media, and the addition of heparin to BMP‐2 promoted differentiation of osteoblasts. Moreover, morphological differentiation was associated with the activity of osteoblasts. This study was shown that, when heparin concentration increases, the early differentiation of the cells was brought about, but the early differentiated cells were rapidly progressed to degenerative changes

본 연구에서는 노후된 기존 콘크리트 포장위에 아스팔트 덧씌우기를 했을 때 윤하중으로 인하여 발생하는 전단 반사균열을 모사할 수 있는 실내 실험방법을 개발하였다. 또한 각 혼합물의 기본 특성시험을 토대로 본 연구에서 개발한 실험방법을 사용하여 각 혼합물의 전단 반사균열 저항 특성을 비교 분석하였다. 그 결과 본 연구에서 개발한 실험방법을 사용하여 측정한 전단 반사균열 저항 특성이 재료 및 보강 효과의 차이를 적절히 보여 현장에서의 상황을 잘 모사할 수 있을 것으로 판단된다. 또한 일부 혼합물에 대하여 기존 피로수명 예측모델을 이용하여 전단 파괴수명을 예측한 결과 높은 상관성을 보여 향후 포장의 수명을 상대적으로 예측하는 것이 가능할 것으로 기대된다.

본 연구는 아스팔트 콘크리트 덧씌우기에서 야기되는 반사균열에 대한 저항성을 향상시키기 위하여 개질재 및 보강재를 사용하여 제조한 혼합물의 성능을 평가하기 위하여 수행하였다. 아스팔트 개질재로는 LDPE와 SBS 및 카본블랙을 이용하였고. 보강재로는 합성섬유(PF), 비닐(PV), 그리드(GG)를 이용하였다. 배합설계를 통해 얻은 최적아스팔트 함량으로 아스팔트 혼합물 슬래브를 제조하였다. 아스팔트 혼합물을 몰드에 붓기 전에 몰드 바닥에 비닐이나 그리드를 미리 깔아 보강 층으로서 만들었다. 갭(균열)이 있는 시멘트 콘크리트 위에 부착된 아스팔트 혼합물 공시체에 유압식 동적하중기를 이용하여 반복하중을 재하하였다. 반복하중에서 균열진전을 측정하여 각 처리 혼합물의 균열 지연효과를 평가하였다. 본 연구의 시험 결과로부터 특정 조합의 아스팔트 혼합물이 휨 파괴(Mode I)에 의한 반사균열 지연에 상당히 효과적인 것으로 나타났다.

본 연구에서는 노후된 기존 콘크리트 포장위에 아스팔트 덧씌우기를 했을 때 윤하중으로 인하여 발생하는 전단 반사균열을 모사할 수 있는 실내 실험방법을 개발하였다. 또한 각 혼합물의 기본 특성시험을 토대로 본 연구에서 개발한 실험방법을 사용하여 각 혼합물의 전단 반사균열 저항 특성을 비교 분석하였다. 그 결과 본 연구에서 개발한 실험방법을 사용하여 측정한 전단 반사균열 저항 특성이 재료 및 보강 효과의 차이를 적절히 보여 현장에서의 상황을 잘 모사할 수 있을 것으로 판단된다. 또한 일부 혼합물에 대하여 기존 피로수명 예측모델을 이용하여 전단 파괴수명을 예측한 결과 높은 상관성을 보여 향후 포장의 수명을 상대적으로 예측하는 것이 가능할 것으로 기대된다.

본 연구는 아스팔트 콘크리트 덧씌우기에서 야기되는 반사균열에 대한 저항성을 향상시키기 위하여 개질재 및 보강재를 사용하여 제조한 혼합물의 성능을 평가하기 위하여 수행하였다. 아스팔트 개질재로는 LDPE와 SBS 및 카본블랙을 이용하였고. 보강재로는 합성섬유(PF), 비닐(PV), 그리드(GG)를 이용하였다. 배합설계를 통해 얻은 최적아스팔트 함량으로 아스팔트 혼합물 슬래브를 제조하였다. 아스팔트 혼합물을 몰드에 붓기 전에 몰드 바닥에 비닐이나 그리드를 미리 깔아 보강 층으로서 만들었다. 갭(균열)이 있는 시멘트 콘크리트 위에 부착된 아스팔트 혼합물 공시체에 유압식 동적하중기를 이용하여 반복하중을 재하하였다. 반복하중에서 균열진전을 측정하여 각 처리 혼합물의 균열 지연효과를 평가하였다. 본 연구의 시험 결과로부터 특정 조합의 아스팔트 혼합물이 휨 파괴(Mode I)에 의한 반사균열 지연에 상당히 효과적인 것으로 나타났다.

The present study examined the effects of Korean white ginseng (WG, Panax ginseng C. A. Meyer) on the learning and memory function and the neural activity in rats with trimethyltin (TMT)-induced memory deficits. The rats were administered with saline or WG (WG 100 or 300 mg/kg, p.o.) daily for 21 days. The cognitive improving efficacy of WG on the amnesic rats, which was induced by TMT, was investigated by assessing the Morris water maze test and by performing immunohistochemistries on choline acetyltransferase (ChAT), acetylcholinesterase (AchE), cAMP responsive element binding protein (CREB) and brain derived neurotrophic factor (BDNF). The rats treated with TMT injection (control group) showed impaired learning and memory of the tasks, but the rats treated with TMT injection and WG administration produced significant improvement of the escape latency to find the platform in the Morris water maze at the 2nd and 4th days compared to that of the control group. In the retention test, the WG 100 and WG 300 groups showed significantly increased crossing number around the platform compared to that of the control group (p < 0.001). Consistently with the behavioral data, result of immunohistochemistry analysis showed that WG 100 mg/kg significantly alleviated the loss of BDNF-ir neurons in the hippocampus compared to that of the control group (p < 0.01). Also, treatment with WG has a trend to be increased the cholinergic neurons in the hippocampal CA1 and CA3 areas as compared to that of the control group. These results suggest that WG may be useful for improving the cognitive function via regulation of neurotrophic activity.