• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.206-206
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• 2008

압전소자를 이용한 초음파 모터는 전자기적 원리로 동작하는 기존의 모터에 비해 구조가 간단하고 소형, 경량화가 가능하며 저속에서 큰 토크가 가능하고 ${\mu}m$단위 까지 정밀제어가 가능하다는 장점 등으로 인해 그 응용분야가 점차 확대되고 있다. 초음파 모터의 원리는 수평과 수직방향에서 변위가 타원형 운동을 형성하는 것이다. 따라서 선택한 타원운동의 방식에 의해서 모터의 형상이 달라진다. 초음파 모터는 액츄에이터를 사용하여 만들기 때문에 액츄에이터의 특성은 모터의 타원변위나 토크에 영향을 미친다. 단판형 액츄에이터에 비하여 적층 액츄에이터는 입력 임피던스를 낮추어 낮은 구동전압에서 구동이 가능하며 큰 변위와 토크를 발생하기 때문에 진동자의 수명 향상과 구동전압을 낮추기에 적합하다. 적층 액츄에이터는 변위량이나 응력 등을 개선하기 위해서 전기기계 결합계수(kp) 및 압전 d상수가 큰 재료가 요구되며, 고전압에서 장시간 구동 시 마찰에 의한 열손실을 감소시키기 위해 높은 기계적 품질계수(Qm)를 가져야한다. 적층 시 내부전극으로 사용하는 Pd, Pt가 함유된 전극은 가격이 비싸 제조비용을 상승시킨다. 상대적으로 값싼 Ag전극을 사용하면 비용절감을 할 수 있지만 융점이 낮아서 저온소결이 불가피하다. 따라서, 특성이 우수한 적층 액츄에이터를 제조하기 위해서 저손실, 저온소결 할 수 있는 액츄에이터 재료가 필요한 실정이다. L1-B4 혈 선혈 초음파 모터는 L1모드와 B4모드의 공진 주파수가 일치하여야 큰 변위를 얻을 수 있는데 이전의 논문에서 Atila를 이용한 시뮬레이션 결과를 분석한 봐 있다. 적층 액츄에이터의 층수를 5,7,9,11,13,15층으로 하여 L1-B4모드에서의 공진주파수를 비교한 결과 13 층일 때 두 모드가 비슷한 공진주파수를 보였고, 티원변위궤적도 다른 층수에 비해 크게 나타났다. 본 연구에서는 시뮬레이션 결과 가장 좋은 특성을 보인 13층 액츄에이터로 선형 초음파 모터를 제작하였다. 또한, 액츄에이터는 압전 및 유전특성이 우수한 저온소결 PZW-PMN-PZT세라믹을 이용하여 제작하였고, 내부전극으로 Ag전극을 사용하였다. 제작된 13 층 선형초음파모터를 가지고 프리로드 및 전압에 따른 속도를 조사하였고, 시뮬레이션 결과와 비교해 보았다.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.263-271
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• 1987

The cyclical trend and seasonal variations of chestnut prices have been analyzed to find out the chestnut price fluctuation in Korea during 1966-1985. The optimum prices, production, and plantation area for the next twenty five years (1986-2010) have been forcasted by the derived equation models. The results of study can be summarized as follows: 1. The chestnut prices were increased by 14.67 percent per annum during 1966-1972, an d decreased by 9.24 percent during 1973-1985, due to the excessive production of chestnut. 2. The chestnut prices showed the lowest price during the harvesting season, especially in October (89.1), and highest in July (109.1). Seasonal fluctuation of chestnut prices were 0.0837 (C.V value) during 1966-1975, and 0.0706 during 1976-1985. Such a seasonal fluctuation of chestnut prices tends to be even with the passage of time. 3. The equation model of predicted chestnut prices was derived as follows : PR=117788.088 - 7.60 TC/Pop + 6.585 GNP/Pop The chestnut prices will be the lowest in 1988, but increased rapidly thereafter. 4. The equation model of optimum chestnut production was derived as follows : $${\ell}n\;PD/Pop=-8.5147-0.8267{\ell}n\;PR+3.3063{\ell}n\;GNP/Pop$$ To maintain optimum chestnut prices according to this model, chestnut production should be 133,000 ton for 1988, and 1,899,000 ton for 2010. 5. Optimum chestnut plantation area will be 4,000 ha in 1988, and thereafter total plantation area will be up to 57,400 ha in 2010.

• Journal of Gastric Cancer
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• v.23 no.1
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• pp.224-249
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• 2023

Gastric cancer is heterogeneous in morphology, biology, genomics, and treatment response. Alterations in human epidermal growth factor receptor 2 (HER2) overexpression, microsatellite instability (MSI) status, programmed death-ligand 1 (PD-L1) levels, and fibroblast growth factor receptor 2 (FGFR2) can be used as biomarkers. Since the combination of fluoropyrimidine/platinum plus trastuzumab that was investigated in the ToGA trial was approved as a standard of care in HER2-positive patients in 2010, no other agents showed efficacy in the first- (HELOISE, LOGiC, JACOB trials) and second- (TyTAN, GATSBY, T-ACT trials) line treatments. Despite the success in treating breast cancer, various anti-HER2 agents, including a monoclonal antibody (pertuzumab), an antibody-drug conjugate (ADC; trastuzumab emtansine [T-DM1]), and a small molecule (lapatinib) failed to translate into clinical benefits until the KEYNOTE-811 (first-line) and DESTINY-Gastri01 (≥second-line) trials were conducted. The incorporation of HER2-directed treatment with immune checkpoint inhibitors in the form of a monoclonal antibody or ADC is now approved as a standard treatment. Despite the promising results of new agents (engineered monoclonal antibodies, bi-specific antibodies, fusion proteins, and small molecules) in the early phase of development, the management of HER2-positive gastric cancer requires further optimization to achieve precision medicine with a chemotherapeutic backbone. Treatment resistance is a complex process that can be overcome using a combination of chemotherapy, targeted agents, and immune checkpoint inhibitors, including novel agents. HER2 status must be reassessed in patients undergoing anti-HER2 treatment with disease progression after the first-line treatment. As a general guideline, patients who need systemic treatment should receive chemotherapy plus targeted agents, anti-angiogenic agents, immune checkpoint inhibitors, or their combinations.

• Hanyang Medical Reviews
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• v.33 no.1
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• pp.10-16
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• 2013

Follicular helper T cells (Tfh) play a significant role in providing T cell help to B cells during the germinal center reaction, where somatic hypermutation, affinity maturation, isotype class switching, and the differentiation of memory B cells and long-lived plasma cells occur. Antigen-specific T cells with IL-6 and IL-21 upregulate CXCR5, which is required for the migration of T cells into B cell follicles, where these T cells mature into Tfh. The surface markers including PD-1, ICOS, and CD40L play a significant role in providing T cell help to B cells. The upregulation of transcription factor Bcl-6 induces the expression of CXCR5, which is an important factor for Tfh differentiation, by inhibiting the expression of other lineage-specific transcription factors such as T-bet, GATA3, and RORγt. Surprisingly, recent evidence suggests that CD4 T cells already committed to Th1, Th2, and Th17 cells obtain flexibility in their differentiation programs by downregulating T-bet, GATA3, and RORγt, upregulating Bcl-6 and thus convert into Tfh. Limiting the numbers of Tfh within germinal centers is important in the regulation of the autoantibody production that is central to autoimmune diseases. Recently, it was revealed that the germinal center reaction and the size of the Tfh population are also regulated by thymus-derived follicular regulatory T cells (Tfr) expressing CXCR5 and Foxp3. Dysregulation of Tfh appears to be a pathogenic cause of autoimmune disease suggesting that tight regulation of Tfh and germinal center reaction by Tfr is essential for maintaining immune tolerance. Therefore, the balance between Tfh and Tfr appears to be a critical peripheral tolerance mechanism that can inhibit autoimmune disorders.

• Clinical and Experimental Pediatrics
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• v.50 no.12
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• pp.1200-1205
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• 2007

Purpose : We performed this study to investigate the outcome of surfactant replacement therapy (SRT) in above nearterm neonates who were required mechanical ventilatory care due to meconium aspiration pneumonia (MAP), respiratory distress syndrome (RDS) or other severe pneumonia (PN). Methods : 48 patients, gestational period ${\geq}36weeks$, who were admitted in NICU of Dongsan Medical Center, Keimyung University between July 1999 and June 2004 were enrolled. They were divided into three groups, MAP group (15 cases), RDS group (27 cases) and PN group (6 cases). All patients were received SRT and evaluated several clinical data (gestational age, oxygen index, duration of ventilator care) and outcome (complications and mortality rate) between pre-SRT and post-SRT. The mean dose of surfactant (modified bovine surfactant, Newfacten, Yuhan Co., Seoul, Korea) was 120 mg/kg. Results : Among each groups, mean pre-SRT OI was higher in MAP group ($21{\pm}3.2$) than other groups, mean duration (days) of ventilatory care and oxygen therapy were similar distributions. Compared with pre-SRT values, significant improvements (P<0.05) in mean values for FiO2 and oxygenation index were documented at 12 hours after SRT. Early complications (persistent pulmonary hypertension of newborm, pneumothorax) and survival rate were lower in MAP group. Within RDS group, earlier SRT (given before 12 hours of life) revealed significantly lower early complication rate than later SRT (given after 12 hours of life) (13.3% vs 58.3%, P<0.05) Conclusion : Our study suggested that SRT seems to be an effective therapy in above nearterm neonates with severe pulmonary disease, and earlier SRT tends to reduce complications in RDS group than later therapy.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.2
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• pp.99-104
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• 2015

The aim of this study is to develop a physiologically based pharmacokinetic (PBPK) model in intra-abdominal infected rats, and extrapolate it to human to predict moxifloxacin pharmacokinetics profiles in various tissues in intra-abdominal infected human. 12 male rats with intra- abdominal infections, induced by Escherichia coli, received a single dose of 40 mg/kg body weight of moxifloxacin. Blood plasma was collected at 5, 10, 20, 30, 60, 120, 240, 480, 1440 min after drug injection. A PBPK model was developed in rats and extrapolated to human using GastroPlus software. The predictions were assessed by comparing predictions and observations. In the plasma concentration versus time profile of moxifloxcinin rats, $C_{max}$ was $11.151{\mu}g/mL$ at 5 min after the intravenous injection and $t_{1/2}$ was 2.936 h. Plasma concentration and kinetics in human were predicted and compared with observed datas. Moxifloxacin penetrated and accumulated with high concentrations in redmarrow, lung, skin, heart, liver, kidney, spleen, muscle tissues in human with intra-abdominal infection. The predicted tissue to plasma concentration ratios in abdominal viscera were between 1.1 and 2.2. When rat plasma concentrations were known, extrapolation of a PBPK model was a method to predict drug pharmacokinetics and penetration in human. Moxifloxacin has a good penetration into liver, kidney, spleen, as well as other tissues in intra-abdominal infected human. Close monitoring are necessary when using moxifloxacin due to its high concentration distribution. This pathological model extrapolation may provide reference to the PK/PD study of antibacterial agents.

• Parasites, Hosts and Diseases
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• v.37 no.3
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• pp.181-188
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• 1999

We investigated the value of mitochondrial small subunit rRNA gene (mt SSU rDNA) PCR-RFLP as a taxonomic tool for Acanthamoeba isolates with close inter-relationships. Twenty-five isolates representing 20 species were included in the analysis. As in nuclear 18s rDNA analysis, two type strains (A. astronyxis and A. tubiashi) of morphological group 1 diverged earliest from the other strains, but the divergence between them was less than in 18s riboprinting. Acanthamoeba griffini of morhological group 2 branched between pathogenic (A. culbertsoni A-1 and A. healyi OC-3A) and nonpathogenic (A.palestinensis Reich, A. pustulosa GE-3a, A. royreba Oak Ridge, and A lenticulata PD2S) strains of morphological group 3. Among the remaining isolates of morphological group 2, the Chang strain had the identical mitochondrial riboprints as the type strain of A. hatchetti. AA2 and AA1, the type strains of A. divionensis and A. paradivionensis, respectively, had the identical riboprints as A. quina Vil3 and A. castellanii Ma. Although the branching orders of A. castellanii Neff, A. polyphaga P23, A. triangularis SH621, and A. lugdunensis L3a were different from those in 18S riboprinting analysis, the results obtained from this study generally coincided well with those from 18S riboprinting. Mitochondrial riboprinting may have an advantage over nuclear 18S rDNA riboprinting beacuse the mt SSU rDNAs do not seem to have introns that are found in the 18S genes of Acanthamoeba and that distort phylogenetic analyses.

• Journal of Periodontal and Implant Science
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• v.34 no.3
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• pp.489-498
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• 2004

Recent studies have demonstrated that human periodontal ligament cells express receptor activation of nuclear factor ${\kappa}B$ ligand (RANKL) which enhances the bone resorbing activity of osteoclasts differentiated from hematopoietic preosteoclasts. The purpose of this study is to determine the effects of p38 MAPK and JNK kinase upon regulating RANKL and OPG in response to $IL-1{\beta}$(l ng/ml) in rat periodontal ligament cells. Soluble RANKL was measured by immunoassay. The effects of p38 MAPK on RANKL and OPG expression was determined by RT-PCR. The results were as follows: 1. Periodontal ligament cells which stimulated by $IL-1{\beta}$ increased soluble RANKL synthesis by dose-dependent pattern. 2. p38 MAP kinase inhibitor (SB203580) showed regulation of soluble RANKL expression by dose-dependent manners. 3. p38 MAP kinase inhibitor (SB203580) regulated the expression of RANKL, but it dose regulate the expresseion of OPG. 4. JNK (c-jun $NH_2-terminal$ kinase) inhibitor (PD98059) did not regulate mRANKL and mOPG. These results suggested that p38 MAPK play a significant role in RANKL gene expression.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.107-112
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• 2006

Free Radical Scavening and inflammatory of the methanol extracts, which were prepared from 6 difffrent bran of rice, were evaluated to investigate bioactive substances. Among them, the extract of C3GHibyeo and Heugjinjubyeo showed strong DPPH scavening activities (73.25% and 50.38% at 0.4 mg/ml, respectively). The extract of C3GHibyeo and Heugjinjubyeo showed strong thrombin inhibition activities (258.76% and 243.52% inhibition at 5 mg/ml, respectively). The result of antibacterial activity by Zone assay showed that C3GHi rice extract $(250{\mu}g\;and\;500{\mu}g)$ inhibited attachment of Helicobactor pylori on the ATCC48504 and COO1 cell line. But no effect on the SEO cell line. Cytotoxicity of blackish purple rice extract on the H. pylori doesn't showed. These result support a functional superiority of rice-base livelihood, and suggest that the development of healthy food using functional ingredients of rice is possible.

• International Journal of Oral Biology
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• v.35 no.3
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• pp.83-89
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• 2010

We investigated the role of the central MAPK pathways in extra-territorial (referred) pain resulting from inflammation of the temporomandibular joint (TMJ). Experiments were carried out on male Sprague-Dawley rats weighing 220-280 g. Under anesthesia, these animals were injected with $50\;{\mu}L$ of complete Freund's adjuvant (CFA) into the TMJ using a Hamilton syringe. In the control group, saline was injected into the TMJ. To identify the extent of inflammation of the TMJ, Evans blue dye (0.1%, 5 mg/kg) was injected intravenously at 1, 3, 6, 9, 12 and 15 days after CFA injection. The concentration of Evans blue dye in the extracted TMJ tissue was found to be significantly higher in the CFA-treated animals than in the saline-treated group. Air-puff thresholds in the vibrissa pad area were evaluated 3 days before and at 3, 6, 9, 12, 15 and 18 days after CFA injection into the TMJ. Referred mechanical allodynia was established at 3 days, remained until 12 days, and recovered to preoperative levels at 18 days after CFA injection. This referred mechanical allodynia was observed in contralateral side area. To investigate the role of central MAPK pathways, MAPK inhibitors ($10\;{\mu}g$) were administrated intracisternally 9 days after CFA injection. SB203580, a p38 MAPK inhibitor, significantly attenuated referred mechanical allodynia, as compared with the vehicle group. PD98059, a MEK inhibitor, also reduced CFA-induced referred mechanical allodynia. These results suggest that TMJ inflammation produces extra-territorial mechanical allodynia, and that this is mediated by central MAPK pathways.