• BMB Reports
• /
• 제40권4호
• /
• pp.554-561
• /
• 2007

Shen and colleagues (Lin et al., 2004) have recently shown that overexpression of the Drosophila DNA methyltransferase 2 isoform C, dDnmt2c, extended life span of fruit flies, probably due to increased expression of small heat shock proteins such as Hsp22 or Hsp26. Here, I demonstrate with immunoprecipitations that overexpressed dDnmt2c interacts with endogenous Hsp70 protein in vivo in S2 cells. However, its C-terminal half, dDnmt2c(178-345) forms approximately 10-fold more Hsp70-containing protein complexe than wild-type dDnmt2c. Overexpressed dDnmt2c(178-345) but not the full length dDnmt2c is able to increase endogenous mRNA levels of the small heat shock proteins, Hsp26 and Hsp22. I provide evidence that dDnmt2c(178-345) increases Hsp26 promoter activity via two heat shock elements, HSE6 and HSE7. Simultaneously overexpressed Hsp40 or a dominant negative form of heat shock factor abrogates the dDnmt2c(178-345)-dependent increase in Hsp26 transcription. The data support a model in which the activation of heat shock factor normally found as an inactive monomer bound to chaperones is linked to the overexpressed C-terminus of dDnmt2c. Despite the differences observed in flies and S2 cells, these findings provide a possible explanation for the extended lifespan in dDnmt2c-overexpressing flies with increased levels of small heat shock proteins.

• 한국정밀공학회지
• /
• 제21권2호
• /
• pp.122-129
• /
• 2004

There is an increasing need for large flat panel display devices. PDP (Plasma Display Panel) is one of the most promising candidates for this need. Thermal shock failure of PDP glass during manufacturing process is a critical issue in PDP industry since it is closely related to the product yield and the production speed. In this study, thermal shock resistance of PDP glass is measured by water quenching test and an analysis scheme is described for estimating transient temperature and stress distributions during thermal shock. Based on the experimental data and the analysis results, a simple procedure for predicting the thermal shock failure of PDP glass is proposed. The fast cooling process for heated glass plates can accelerate the speed of PDP production, but often leads to thermal shock failure of the glass plates. Therefore, a design guideline for preventing the failure is presented from a viewpoint of high speed PDP manufacturing process. This design guideline can be used for PDP process design and thermal -shock failure prevention.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2000년도 춘계 학술대회논문집
• /
• pp.39-44
• /
• 2000

Two-dimensional Navier-Stokes codes are used to simulate the shock tunnel in Konkuk university. In order to design experiments in impulse facilities properly and to interpret data from such facilities, it is necessary to understand how the flow approaches steady state. This is done by determining the transient flow field and flow establishment time around a given model. This will be accomplished by developing appropriate CFD codes which solve the Navier-Stokes equations, and simulating the starting process and resulting unsteady viscous flow phenomena. The starting process in a shock tunnel consists of multiple shock interactions and contact discontinuities, which are difficult to solve with the classical shock capturing schemes. A recently developed high resolution scheme is adapted for resolving the unsteady phenomena of those multiple shock interactions and contact surfaces during the starting process. The bifurcation phenomenon due to the interactions of the reflected shock from the end of the shock tube with the boundary layer generated by the incident shock becomes of particular interest. By comparing with the experiment results, the accuracy of the numerical analysis is validated and it is demonstrated that the properties which can hardly be obtained through the experiment can be estimated.

• 동의신경정신과학회지
• /
• 제11권1호
• /
• pp.37-46
• /
• 2000

We investigated the effects of lemon pure essential oils on the heat shock-induced apoptosis in human astrocyte cell line CCF-STTG1. In previous studies, hear shock has been reported to induce the apoptosis or programmed cell death through the activation of caspase-3. Treatment of CCF-STTG1 cells with heat shock markedly induced apoptotic cell death as determined by flow cytometry. Interestingly, pretreatment of CCF-STTG1 cells with lemon pure essential oils inhibited the heat shock-induced apoptosis. Lemon also inhibited the heat shock-induced apoptosis in primary cultured rat astrocytes. To determine whether lemon inhibits the heat shock-induced activation of these apoptotic proteases, activation of CPP32 was assessed by Western blotting. Consistent with flow cytometry, DNA fragmentation and giemsa staining, heat shock-induced activation of CPP32 was blocked by lemon pure essential oil. PARP, cysteine protease substrates were fragmented as a consequence of apoptosis by heat shock. Lemon oil inhibited the PARP fragmentation. This essential oil also inhibited the heat shock-induced activation of caspase-3. These results suggest that lemon pure essential oils may modulate the apoptosis through the activation of the ICE-like caspases.

• 한국가시화정보학회지
• /
• 제10권2호
• /
• pp.32-38
• /
• 2012

In recent years a unique drug delivery system named as the transdermal drug delivery system has been developed which can deliver drug particles to the human skin without using any external needle. The solid drug particles are accelerated by means of high speed gas flow through a shock tube imparting enough momentum so that particles can penetrate through the outer layer of the skin. Different systems have been tried and tested in order to make it more convenient for clinical use. One of them is the contoured shock tube system (CST). The contoured shock tube consists of a classical shock tube connected with a correctly expanded supersonic nozzle. A set of bursting membrane are placed upstream of the nozzle section which retains the drug particle as well as initiates the gas flow (act as a diaphragm in a shock tube). The key feature of the CST system is it can deliver particles with a controllable velocity and spatial distribution. The flow dynamics of the contoured shock tube is analyzed numerically using computational fluid dynamics (CFD). To validate the numerical approach pressure histories in different sections on the CST are compared with the experimental results. The key features of the flow field have been studied and analyzed in details. To investigate the performance of the CST system flow behavior through the shock tube under different operating conditions are also observed.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.1643-1648
• /
• 2004

When a shock wave propagates into a Helmholtz resonator, very complicated wave phenomena are formed both inside and outside the resonator tube. Shock wave reflection, shock focusing phenomena and shock-vortex interactions cause strong pressure fluctuations inside the resonator, consequently leading to powerful sound emission. In the present study, the wave phenomena inside and outside the Helmholtz resonator are, in detail, investigated with a help of CFD. The Mach number of the incident shock wave is varied below 2.0 and several types of resonators are tested to investigate the influence of resonator geometry on the wave phenomena. A TVD scheme is employed to solve the axisymmetric, compressible, Euler equations. The results obtained show that the configuration of the Helmholtz resonator significantly affects the peak pressure of shock wave focusing, its location, the amplitude of the discharged wave and resonance frequency.

• 대한기계학회논문집B
• /
• 제22권9호
• /
• pp.1229-1237
• /
• 1998

Experiments of shock-wave/turbulent boundary layer interaction were conducted by using a supersonic wind tunnel. Nominal Mach number was varied in the range of 1.6 to 3.0 by means of different nozzles. The objective of the present study is to investigate the effects of boundary layer suction on normal shock-wave oscillations caused by shock wave/boundary layer interaction in a straight duct. Two-dimensional slits were installed on the top and bottom walls of the duct to bleed turbulent boundary layer flows. The bleed flows were measured by an orifice. The ratio of the bleed mass flow to main mass flow was controlled below the range of 11 per cent. Time-mean and fluctuating wall pressures were measured, and Schlieren optical observations were made to investigate time-mean flow field. Time variations in the shock wave displacement were obtained by a high-speed camera system. The results show that boundary layer suction by slits considerably reduce shock-wave oscillations. For the design Mach number of 2.3, the maximum amplitude of the oscillating shock-wave reduces by about 75% compared with the case of no slit for boundary layer suction.

• 조명전기설비학회논문지
• /
• 제20권6호
• /
• pp.63-68
• /
• 2006

22,900[V] 전압에서 발생하는 감전사고를 살펴보기 위하여 최근의 감전사고에 대한 통계자료를 분석하였다. 22,900[V] 전압의 감전사고의 메커니즘을 실증하기 위해서 분석 결과에 근거하여 모의 감전사고 실험을 수행하였다. 실험에서는 여러 가지 상황에서 모의된 감전사고의 위험성을 정량적으로 분석하기 위하여 인체모형에 흐르는 전류를 측정하였다. 실험결과 감전 상황과 관계없이 일단 감전사고가 발생하면 인체에 치명적인 것으로 밝혀졌다.

• 근관절건강학회지
• /
• 제29권1호
• /
• pp.60-68
• /
• 2022

Purpose: This study aimed to investigate the changes in reality shock among new nurses and their influencing factors to identify turnover reduction methods. Methods: A total of 146 new nurses from 6 general hospitals participated in the survey. The survey data were collected from August 5 to November 10, 2015. Results: The mean scores for factors related to turn over were 2.75 for nurse practice environment, 2.84 (4point scale) for reality shock, and 3.08 (5point scale) for turnover intention. A significant difference in the impact of reality shock was observed depending on whether the nurses selected their work unit (F=6.24, p=.003) and whether they could take the possibility of holiday on the desired day at will (t=-2.57, p=.013). Changes in reality shock correlated with turnover intention, with the 'increased reality shock' group demonstrating an odds ratio of 2.37 (CI: 1.41~3.98) for turnover intention. Conclusion: The current findings indicate the need for lowering reality shock and turnover intention by considering nurses' work-related characteristics and improving their practice environments. To further study the changes in reality shock new nurses experienced, additional research is warranted while homogenizing the participants in terms of preceptorship duration and timing of independence.

• 융합보안논문지
• /
• 제12권5호
• /
• pp.51-59
• /
• 2012

본 연구는 민간경비원들의 사건충격이 직무스트레스에 미치는 영향을 심층적으로 분석하고 규명하는데 목적이 있다. 이러한 본 연구의 목적을 달성하기 위하여 2012년 수도권소재 민간경비원 10명을 대상으로 참여관찰과 심층면담분석방법을 이용하였다. 수집된 인터뷰 자료는 컴퓨터를 이용하여 부호화 하였으며, 사건충격, 직무영향, 직무스트레스, 조직생활 등으로 분석하였다. 결론은 다음과 같다. 첫째, 민간경비원들은 업무현장에서 발생된 자살, 테러위협, 상사의 비리 등과 같은 사건충격은 큰 심리적 불안감을 주고 있는 것으로 나타났다. 둘째, 민간경비원들은 과거에 겪었던 사건충격으로 인해 업무에 대한 두려움, 대인기피 증 현상으로 인해 타 업무 분야로 이직하는데 중요한 영향을 미치고 있는 것으로 나타났다. 셋째, 민간경비원들은 과거 자신이 경험한 사건충격으로 인해 상당부분의 직무스트레스를 경험했던 것으로 나타났다. 즉, 과거 사건충격은 고객접점에 직접적인 영향을 미친다. 넷째, 민간경비원들은 과거 사건충격을 극복하지 못할 경우 개인의 조직생활을 감소시키는 것으로 나타났다. 즉, 사건충격은 민간경비 조직문화에서 상사부하간의 신뢰형성 및 팀웍을 감소시킨다.