• Journal of Ginseng Research
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• v.40 no.3
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• pp.304-308
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• 2016

Background: Joboksansam, Korean bird wild ginseng, is an artificially cultivated wild ginseng germinated from bird feces. Although numerous pharmacologic activities of wild ginsengs have been reported, the beneficial effect of joboksansam in cancer has not been elucidated. In this study, we investigated the in vivo and in vitro anticancer activities of joboksansam powder. Methods: To evaluate the in vivo anticancer activity of joboksansam, we established a xenograft mouse model bearing RMA cell-derived cancer. Direct cytotoxicity induced by joboksansam powder was also investigated in vitro using (3-4-5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide (MTT) assay. The inhibitory activity of this powder on the activation of cell survival signaling involving Akt and Src was examined with immunoblot analysis. Results: Joboksansam powder displayed strong inhibitory activity against the increased tumor size, increased weight of total body and cancer tissues, and mortality of tumor-bearing mice. Joboksansam powder also suppressed the activation of survival regulatory enzymes Akt and Src, as assessed by phosphorylation levels in the immunoblot analysis of tumor tissues. Interestingly, the viability of RMA cells in vitro was directly decreased by joboksansam treatment. Conclusion: Overall, our results strongly suggest that joboksansam powder has the potential to protect against cancer generation by direct cytotoxic effects on cancer cells resulting from suppression of cell survival signaling.

• Journal of Ginseng Research
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• v.31 no.3
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• pp.159-174
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• 2007

Pharmacology of Korean Red ginseng gives us unique possibility to develop new class of antiepileptic drugs today and to improve one's biological activity. The chemical structures of ginsenosides (GS) have some principal differences from well-known antiepileptic new generation drugs. The antiepileptic effect of GS was also demonstrated in all models of epilepsy in rats (young and adult), which have studied, in all models of epilepsy including status epilepticus (SE), induced by lithium - pilocarpine. In our experiments in rats new evidences on protective effects were exerted as a result of premedication by GS. Pre-treatment of several GS could induce decrease of the seizures severity and brain structural damage (by MRI), neuronal degeneration in hippocampus. Wave nature of severity of motor seizures during convulsive SE was observed during lithium-pilocarpine model of SE in rats (the first increase of seizures was 30 min after the beginning of SE and the second - 90 min after. The efficacy of treatment on SE by ginsenoside as expected was observed after no less 3 weeks by daily GS i.p. administration. It is blocked SE or significantly decrease the severity of seizures during SE. The implication of presented data is that combination of ginsenosides from Korean Red ginseng and ginseng cell culture Dan25 that could be applied for prevention of epileptical status development. However, a development of optimal ratio of different ginsenosides $(Rb_1$ Rc, Rg, Rf,) should consummate in the new antiepileptic drug development.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2E
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• pp.73-86
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• 1995

The transducer section of the forward-looking ultrasound imaging catheter (FLUIC) consists of a circular piezoelectric element as a vibrator and a conical acoustic mirror as a perfect reflector. A small diameter piezoelectric transducer element is mounted on the side of a catheter's rotating shaft. The unique design of FLUIC provides the capability to form a two-dimensional image of a cross-section of vessel in front of the catheter, which is lacking in the present generation of intravascular ultrasound (IVUS) transducers, as well as a conventional side view image. The mirror configuration for the transducer section of the FLUIC is designed using an approximated ray tracing techniques. The diffraction transfer function approach [1] developed for the field prediction from primary sources is generalized and extended to predict the secondary diffraction characterstics from an acoustic mirror. The extended model is verified by simulation and experiment through a simple plane reflector and employed to analyzed the field characteristics of a FLUIC.

• The Journal of the Acoustical Society of Korea
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• v.32 no.2
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• pp.116-123
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• 2013

This paper represents generation of time-varying underwater acoustic channels by performing scattering simulation with time-varying ocean surface and Kirchhoff approximation. In order to estimate the time-varying ocean surface, 1D Pierson-Moskowitz ocean power spectrum and Gaussian correlation function were used. The computed scattering coefficients are applied to the amplitudes of each impulse of BELLHOP simulation result. The scattering coefficients are then compared with measured doppler spectral density of signal components which were scattered from ocean surface and the correlation time used in the Gaussian correlation function was estimated by the comparison. Finally, bit-error-rate and channel correlation simulations were performed with the generated time-varying channel based on passive time-reversal communication scenario.

• Korean Journal of Human Ecology
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• v.19 no.6
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• pp.1031-1044
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• 2010

Corresponding to the rapid growth of the aging population without an adequate social safety net for the elderly, older people face great disadvantages due to sudden illness or poor health and a lack of support from the younger generation. Furthermore, older women are suffering from a drastic deterioration of their economic status because of insufficient retirement savings. Examining the impact of labor force participation and living arrangement on health status and life satisfaction in later life, it is important to consider gender differences in context of social policies for the elderly. Using data based on a stratified national sample of the elderly by the Korean Longitudinal Study of Aging (KLoSA), multiple regression model were used to estimate the relationships between labor force participation and health status and subjective life satisfaction concerning the quality of their later life. The result indicates that good health status and high level of life satisfaction are associated with the type of paid work status for the elderly men, but those are associated with the type of non paid work, such as family businesses employees for the elderly women. Significant differences in chronic health condition and subjective life satisfaction by employment characteristics are found among the elderly. In addition, older women's high level of life satisfaction was associated with the participation of the social activity. The major conclusion from these results should help us understand gender differences in the elderly and acknowledge further exploration of gender variations in these people's later life.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3065-3072
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• 2013

Direct synthesis of $H_2O_2$ and in situ oxidative desulfurization of model fuel over Au/Ti-HMS and Au/TS-1 catalysts has been comparatively investigated in water or methanol. Maximum amount (82%) of active $Au^0$ species for $H_2O_2$ synthesis was obtained. Au/Ti-HMS and Au/TS-1 exhibited the contrary performances in $H_2O_2$ synthesis as $CH_3OH/H_2O$ ratio of solvent changed. $H_2O_2$ decomposition and hydrogenation in water was inhibited by the introduction of methanol. Effect of $O_2/H_2$ ratio on $H_2O_2$ concentration, $H_2$ conversion and $H_2O_2$ selectivity revealed a relationship between $H_2O_2$ generation and $H_2$ consumption. The highest dibenzothiophene removal rate (83.2%) was obtained over Au/Ti-HMS in methanol at 1.5 of $O_2/H_2$ ratio and $60^{\circ}C$. But removal of thiophene over Au/TS-1 should be performed in water without heating to obtain a high removal rate (61.3%). Meanwhile, $H_2$ conversion and oxidative desulfurization selectivity of $H_2$ were presented.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.197-202
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• 2012

Block Train Services(BTS) are actively studied in many countries for higher productivity and eco-friendly systems of inland freight distribution. However it is difficult for an ordinary student or researcher to approach for understanding and studying BTS because rail transport is operated monopolistically by Korea government and most freight information in each company belongs to its business secret due to the industrial characteristics. For such reasons, the study aimed to develop a BTS simulation model that it supports understanding and strategic decision required for BT operation. To build the result, expert depth-interviews were conducted with analysis of relative references through the domestic representative BT operating company K. The simulator refers to the Busan NewPort-Uiwang section and functionally, it supports scenario generation and analysis on BT operation. It makes a contribution to study a new type's technological application for learning and strategic analysis of BTS.

• Molecules and Cells
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• v.43 no.7
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• pp.662-670
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• 2020

We have investigated the involvement of the pre-mRNA processing factor 4B (PRP4) kinase domain in mediating drug resistance. HCT116 cells were treated with curcumin, and apoptosis was assessed based on flow cytometry and the generation of reactive oxygen species (ROS). Cells were then transfected with PRP4 or pre-mRNA-processing-splicing factor 8 (PRP8), and drug resistance was analyzed both in vitro and in vivo. Furthermore, we deleted the kinase domain in PRP4 using Gateway™ technology. Curcumin induced cell death through the production of ROS and decreased the activation of survival signals, but PRP4 overexpression reversed the curcumin-induced oxidative stress and apoptosis. PRP8 failed to reverse the curcumin-induced apoptosis in the HCT116 colon cancer cell line. In xenograft mouse model experiments, curcumin effectively reduced tumour size whereas PRP4 conferred resistance to curcumin, which was evident from increasing tumour size, while PRP8 failed to regulate the curcumin action. PRP4 overexpression altered the morphology, rearranged the actin cytoskeleton, triggered epithelial-mesenchymal transition (EMT), and decreased the invasiveness of HCT116 cells. The loss of E-cadherin, a hallmark of EMT, was observed in HCT116 cells overexpressing PRP4. Moreover, we observed that the EMT-inducing potential of PRP4 was aborted after the deletion of its kinase domain. Collectively, our investigations suggest that the PRP4 kinase domain is responsible for promoting drug resistance to curcumin by inducing EMT. Further evaluation of PRP4-induced inhibition of cell death and PRP4 kinase domain interactions with various other proteins might lead to the development of novel approaches for overcoming drug resistance in patients with colon cancer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.1
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• pp.77-87
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• 2003

The residual stress and birefringence in injection-molded plastic parts can be divided into the flow-induced residual stress and birefringence produced in flowing stage, the thermally-induced residual stress and birefringence produced in cooling stage. However, the physics involved in the generation of the thermally-induced residual stress and birefringence still remains to be understood. Because polymer experiences viscoelastic history near the glass-transition temperature it is hard to model the entire process. Volume relaxation phenomenon was included to predict the final thermally-induced residual stress and birefringence in quenched plastic parts more accurately. The present study focused on comparing the predicted values far thermally-induced residual stress and birefringence with and without volume relaxation behavior (or free volume theory) under free and constrained quenching conditions. As a result, tile residual stress remained as a tensile stress at the center and as a compressible stress near the surface for the free quenching cases. In contract the residual stress remained as a compressible stress at the center and as a tensile stress near the surface fur the constrained quenching cases. The residual birefringence remained as minus values at the center and as plus values near the surface for the free quenching cases. Interestingly the residual birefringence showed minus values in entire zone for the constrained quenching cases. In the prediction of birefringence only the case including free volume theory showed the correct result for the distribution of birefringence in thickness direction.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.403-404
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• 2013

최근 scaling down의 한계에 부딪힌 DRAM과 Flash Memory를 대체하기 위한 차세대 메모리(Next Generation Memory)에 대한 연구가 활발히 진행되고 있다. ITRS (international technology roadmap for semiconductors)에 따르면 PRAM (phase change RAM), RRAM (resistive RAM), STT-MRAM (spin transfer torque magnetic RAM) 등이 차세대 메모리로써 부상하고 있다. 그 중 RRAM은 간단한 구조로 인한 고집적화, 빠른 program/erase 속도 (100~10 ns), 낮은 동작 전압 등의 장점을 갖고 있어 다른 차세대 메모리 중에서도 높은 평가를 받고 있다 [1]. 현재 RRAM은 주로 금속-산화물계(Metal-Oxide) 저항 변화 물질을 기반으로 연구가 활발하게 진행되고 있다. 하지만 근본적으로 공정 과정에서 산소에 의한 오염으로 인해 수율이 낮은 문제를 갖고 있으며, Endurance 및 Retention 등의 신뢰성이 떨어지는 단점이 있다. 따라서, 본 연구진은 산소 오염에 의한 신뢰성 문제를 근본적으로 해결할 수 있는 다양한 금속-질화물(Metal-Nitride) 기반의 저항 변화 물질을 제안해 연구를 진행하고 있으며, 우수한 열적 안정성($>450^{\circ}C$, 높은 종횡비, Cu 확산 방지 역할, 높은 공정 호환성 [2] 등의 장점을 가진 WN 박막을 저항 변화 물질로 사용하여 저항 변화 메모리를 구현하기 위한 연구를 진행하였다. WN 박막은 RF magnetron sputtering 방법을 사용하여 Ar/$N_2$ 가스를 20/30 sccm, 동작 압력 20 mTorr 조건에서 120 nm 의 두께로 증착하였고, E-beam Evaporation 방법을 통하여 Ti 상부 전극을 100 nm 증착하였다. I-V 실험결과, WN 기반의 RRAM은 양전압에서 SET 동작이 일어나며, 음전압에서 RESET 동작을 하는 bipolar 스위칭 특성을 보였으며, 읽기 전압 0.1 V에서 ~1 order의 저항비를 확보하였다. 신뢰성 분석 결과, $10^3$번의 Endurance 특성 및 $10^5$초의 긴 Retention time을 확보할 수 있었다. 또한, 고저항 상태에서는 Space-charge-limited Conduction, 저저항 상태에서는 Ohmic Conduction의 전도 특성을 보임에 따라 저항 변화 메카니즘이 filamentary conduction model로 확인되었다 [3]. 본 연구에서 개발한 WN 기반의 RRAM은 우수한 저항 변화 특성과 함께 높은 재료적 안정성, 그리고 기존 반도체 공정 호환성이 매우 높은 강점을 갖고 있어 핵심적인 차세대 메모리가 될 것으로 기대된다.