• 한국운동역학회지
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• 제26권2호
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• pp.167-174
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• 2016

Objective: The purpose of this study was to determine the interrelationship between ranges of motion of the knee and ankle joints on the sagittal plane and the attenuation magnitude of impact shock at high frequency (9~20 Hz) in the support phase during downhill running. Method: Fifteen male heel-toe runners with no history of lower extremity injuries were recruited for this study (age, $25.07{\pm}5.35years$; height, $175.4{\pm}4.6cm$; mass, $75.8{\pm}.70kg$). Two uniaxial accelerometers were mounted to the tuberosity of tibia and sacrum, respectively, to measure acceleration signals. The participants were asked to run at their preferred running speed on a treadmill set at $0^{\circ}$, $7^{\circ}$, and $15^{\circ}$ downhill. Six optical cameras were placed around the treadmill to capture the coordinates of the joints of the lower extremities. The power spectrum densities of the two acceleration signals were analyzed and used in the transfer function describing the gain and attenuation of impact shock between the tibia and the sacrum. Angles of the knee and ankle joints on the sagittal plane and their angle ranges were calculated. The Pearson correlation coefficient was used to test the relationship between two variables, the magnitude of impact shock, and the range of joint angle under three downhill conditions. The alpha level was set at .05. Results: Close correlations were observed between the knee joint range of motion and the attenuation magnitude of impact shock regardless of running slopes (p<.05), and positive correlations were found between the ranges of motion of the knee and ankle joints and the attenuation magnitude of impact shock in $15^{\circ}$ downhill running (p<.05). Conclusion: In conclusion, increased knee flexion might be required to attenuate impact shock during downhill and level running through change in stride or cadence while maintaining stability, and strong and flexible ankle joints are also needed in steeper downhill running.

• The Korean Journal of Physiology and Pharmacology
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• 제22권4호
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• pp.457-465
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• 2018

The expression of BCL-2 interacting cell death suppressor (BIS), an anti-stress or anti-apoptotic protein, has been shown to be regulated at the transcriptional level by heat shock factor 1 (HSF1) upon various stresses. Recently, HSF1 was also shown to bind to BIS, but the significance of these protein-protein interactions on HSF1 activity has not been fully defined. In the present study, we observed that complete depletion of BIS using a CRISPR/Cas9 system in A549 non-small cell lung cancer did not affect the induction of heat shock protein (HSP) 70 and HSP27 mRNAs under various stress conditions such as heat shock, proteotoxic stress, and oxidative stress. The lack of a functional association of BIS with HSF1 activity was also demonstrated by transient downregulation of BIS by siRNA in A549 and U87 glioblastoma cells. Endogenous BIS mRNA levels were significantly suppressed in BIS knockout (KO) A549 cells compared to BIS wild type (WT) A549 cells at the constitutive and inducible levels. The promoter activities of BIS and HSP70 as well as the degradation rate of BIS mRNA were not influenced by depletion of BIS. In addition, the expression levels of the mutant BIS construct, in which 14 bp were deleted as in BIS-KO A549 cells, were not different from those of the WT BIS construct, indicating that mRNA stability was not the mechanism for autoregulation of BIS. Our results suggested that BIS was not required for HSF1 activity, but was required for its own expression, which involved an HSF1-independent pathway.

• 한국항공우주학회지
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• 제40권12호
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• pp.1025-1031
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• 2012

본 연구에서는 간단한 압축성 유체이론에 기초하여 렘젯 엔진의 초음속 흡입구를 개념 설계하고 보다 넓은 범위의 운영조건에서 안정적인 성능을 내도록 블리딩 유동제어 연구를 수행하였다. 초음속 흡입구의 성능을 개선시키기 위해서는 충격파 안정성, 충격파-경계층 상호작용 및 유동 박리를 적절히 제어할 수 있어야 한다. 비점성 해석을 통해 얻어진 1차 기초설계 형상으로부터 점성을 고려하여 충격파의 강도와 경계층 및 박리의 효과가 반영된 2차 수정설계를 수행하였다. 그 결과 설계조건에서 충격파가 안정화되고 목표 흡입 유량을 만족하는 형상을 얻었다. 흡입구가 탈 설계조건 내에서도 성능이 유지되도록 하기 위해 블리딩을 적용하였다. 질량유량 경계조건을 이용하여 블리딩 효과를 모델링 하였으며 위치와 개수를 조절해가며 성능변화를 관찰하였다.

• Journal of Microbiology and Biotechnology
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• 제24권8호
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• pp.1118-1122
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• 2014

The present study shows that DR1114 (Hsp20), a small heat shock protein of the radiation-resistant bacterium Deinococcus radiodurans, enhances tolerance to hydrogen peroxide ($H_2O_2$) stress when expressed in Escherichia coli. A protein profile comparison showed that E. coli cells overexpressing D. radiodurans Hsp20 (EC-pHsp20) activated the redox state proteins, thus maintaining redox homeostasis. The cells also showed increased expression of pseudouridine (psi) synthases, which are important to the stability and proper functioning of structural RNA molecules. We found that the D. radiodurans mutant strain, which lacks a psi synthase (DR0896), was more sensitive to $H_2O_2$ stress than wild type. These suggest that an increased expression of proteins involved in the control of redox state homeostasis along with more stable ribosomal function may explain the improved tolerance of EC-pHsp20 to $H_2O_2$ stress.

• 산경연구논집
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• 제8권7호
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• pp.7-12
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• 2017

Purpose - This research examines the short-run and long-run effect of external shocks (oil price and exchange rate) on domestic food price in Indonesia. Research design, data, and methodology - Three variables are used in this research. The variables are food price index, Rupiah's exchange rate of Indonesia, and crude oil price from 1998 until 2015 using Vector Error Correction Model (VECM). Results - The increasing of oil price and the depreciation of Rupiah's rate push the domestic food price in long-run, but do not impact significantly in short- term. The response of food price to oil prices shock and exchange rate shock are positive and persistent throughout the entire sample period. The exchange rate and oil price shocks have a small proportion explaining for the fluctuations of food price index but increasing over time. Conclusions - The policymaker should concern on solving the problem of oil price increase and depreciation of exchange rate on Indonesia's food price as they are important factors that can affect the price stability. The government should not rely on food imports because the price is strongly influenced by the movements in the exchange rate.

• 물과 미래
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• 제21권2호
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• pp.173-182
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• 1988

St. Venant식에서 상대적으로 마찰경사항이 크고 연속적 파형이 유입하는 경우와 급격한 불연속 부위를 가진 충격파가 유입하는 경우에 유한차분 수치해의 특성을 비교하였다. 그 결과 단일 증감파에는 Keller Box 해법이 $0.5{\leq}{\theta}{\leq}1.0$, ${\theta}+{\psi}$=1로 두 매개변수를 정했을 때 정확도와 효율성, 안전성의 측면에서 가장 좋았다. 그러나 충격파에서는 Preissmann 형태의 매개변수 ${\psi}$(=0.5)를 사용하여야만 안정하였다. Lax-Wendroff, Richtmyer 해법은 Leap Frog에 비해 안정성에서, Lax-Fredrich 해법에 비해 정확성에서 더 좋은 방법임이 단일 증감파의 수치실험에서 나타났고, 충격파에서는 Lax-Fredrich가 다른 양해법들에 비해 과도한 수치적 dissipation을 Leap Frog은 느린 질량전달을 보였다.

• 전력전자학회논문지
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• 제23권5호
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• pp.305-312
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• 2018

DC distribution systems has recently taken the spotlight. Concerns over human safety and stability facility are raised in DC distribution systems. Std. IEC 60479 provides basic guidance on "the effects of shock current on human beings and livestock" for use in the establishment of electrical safety requirements and suggests an electrical impedance of the human body. This study analyzes impedance spectrums based on the electrical equivalent impedance circuit for the human body; human body impedances measured by experiments are analyzed below the fundamental frequency (60 Hz). The analysis shows that the equivalent impedance circuit for the human body should be modified at least in low-frequency range below the fundamental frequency (60 Hz). The DC residual current detection method that can classify electric shock accidents of humans and electric leakages of facilities is proposed by applying the analysis result. The detection method is verified by experiments on livestock.

• BMB Reports
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• 제40권1호
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• pp.107-112
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• 2007

To study the functioning of HSP70 in Escherichia coli, we selected NtHSP70-2 (AY372070) from among three genomic clones isolated in Nicotiana tabacum. Recombinant NtHSP70-2, containing a hexahistidine tag at the amino-terminus, was constructed, expressed in E. coli, and purified by $Ni^{2+}$ affinity chromatography and Q Sepharose Fast Flow anion exchange chromatography. The expressed fusion protein, $H_6NtHSP70$-2 (hexahistidine-tagged Nicotiana tabacum heat shock protein 70-2), maintained the stability of E. coli proteins up to 90$^{\circ}C$. Measuring the light scattering of luciferase (luc) revealed that NtHSP70-2 prevents the aggregation of luc without ATP during high-temperature stress. In a functional bioassay (1 h at 50$^{\circ}C$) for recombinant $H_6NtHSP70$-2, E. coli cells overexpressing $H_6NtHSP70$-2 survived about seven times longer than those lacking $H_6NtHSP70$-2. After 2 h at 50$^{\circ}C$, only the E. coli overexpressing $H_6NtHSP70$-2 survived under such conditions. Our NtHSP70-2 bioassays, as well as in vitro studies, strongly suggest that HSP70 confers thermo-tolerance to E. coli.

• 한국추진공학회지
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• 제23권4호
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• pp.10-20
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• 2019

충격파 개념을 이용하는 유체 추력벡터 제어는 빠른 벡터링 응답, 간단한 구조 및 낮은 무게로 인하여 큰 벡터링 성능을 달성하는데 많은 이점을 제공한다. 본 논문에서는 전산유체역학 기법을 사용하여 슬롯 인젝터를 가진 3차원 직사각형 초음속 노즐에 대하여 연구를 수행하였다. 계산 방법론을 검증하기 위하여 수치 결과를 실험 데이터로 비교하였다. 대칭 평면에서의 상부 및 하부 노즐벽을 따르는 압력분포는 시험 결과와 잘 일치하였다. $k-{\omega}$ SST 난류모델을 기반으로 한 수치해석을 통하여, 운동량 플럭스 비율의 영향을 철저히 조사하여 추력의 성능 변화를 명확하게 나타내었다.

• 로봇학회논문지
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• 제17권1호
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• pp.48-57
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• 2022

In this paper, we propose a legged landing platform for the quadcopter taking off and landing in the ship environment. In the ship environment with waves and winds, the aircraft has risks being overturned by contact impact and excessive inclination during landing on the ship. This landing platform has four landing legs under the quadcopter for balancing and shock relief. In order to make the quadcopter balanced on ships, the position of each end effector was controlled by PID control. And shocks have mainly happened when quadcopter contacts the ship's surface as well as legs move fast. Hence, impedance control was used to cope with the shocks. The performance of the landing platform was demonstrated by a simulation and a prototype in three sea states based on a specific size of a ship. During landing and tracking the slope of the ship's surface, oscillations of rotation and translation from the shock were mitigated by the controller. As a result, it was verified that transient response and stability got better by adding impedance control in simulation models and prototype experiments.