• Korean Journal of Applied Biomechanics
• /
• v.28 no.2
• /
• pp.135-141
• /
• 2018

Objective: The purpose of this study was to investigate the effect of functional ankle instability (FAI) and surgical treatment (ST) on postural stability and leg stiffness during vertical-drop landing. Method: A total of 21 men participated in this study (normal [NOR]: 7, FAI: 7, ST: 7). We estimated dimensionless leg stiffness as the ratio of the peak vertical ground reaction force and the change in stance-phase leg length. Leg length was calculated as the distance from the center of the pelvis to the center of pressure under the foot. Furthermore, the analyzed variables included the loading rate and the dynamic postural stability index (DPSI; medial-lateral [ML], anterior-posterior [AP], and vertical [V]) in the initial contact phase. Results: The dimensionless leg stiffness in the FAI group was higher than that of the NOR group and the ST group (p = .018). This result may be due to a smaller change in stance-phase leg length (p = .001). DPSI (ML, AP, and V) and loading rate did not show differences according to the types of ankle instability during drop landing (p > .05). Conclusion: This study suggested that the dimensionless leg stiffness was within the normal range in the ST group, whereas it was increased by the stiffness of the legs rather than the peak vertical force during vertical-drop landing in the FAI group. Identifying these potential differences may enable clinicians to assess ankle instability and design rehabilitation protocols specific for the impairment.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.121.1-121
• /
• 2001

Congestion control is a critical issue in TCP networks, Recently, active queue management (AQM) was proposed for congestion control at routers. The random early detection RED algorithm is widely known in the AQM algorithms, We present an adaptive nonlinear RED (NRED) algorithm, which has nonlinear drop probability profile. The proposed algorithm enhanced the performance of the RED algorithm by the self-parameterization based on the traffic load Furthermore, the proposed algorithm can effectively adapt itself between he RED and the drop-tail queue management by adopting proper nonlinearity in the drop probability profile. Through simulation, we show the effectiveness of the proposed algorithm comparing with the drop-tail and the original RED algorithm.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.67 no.3
• /
• pp.155-159
• /
• 2018

Recently, the expansion or establishment of facilities for the logistics system is increasing. Conveyor facilities play a major role in sorting and transporting logistics. Induction motors are widely used for the operation of these conveyor systems. In the logistics system, a large number of induction motors are used. These motors have a considerable distance from the power source side and have a low power factor. The installation position for the power factor compensation of the induction motor is very important. Since the voltage drop depends on the length of the line, it is an important parameter in capacitor capacity determination for power factor compensation. The capacity of the capacitors installed to compensate the power factor of the inductive load should be designed to the extent that self-excitation does not occur. In this study, we analyze the method of compensating the proper power factor considering the voltage drop and the installation position of the induction motor in the logistics system.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.3
• /
• pp.205-209
• /
• 2017

Unlike spherical drop impact, ellipsoidal drop impact can control the bouncing height on a heated surface by significantly altering impact behavior. To scrutinize the effect of the aspect ratio (AR) of the drop on the bounce suppression, in this study, non-axisymmetric spreading behaviors are observed from two side views and characterized based on the spreading width of the drop for horizontal principal axes. In addition, the maximum spreading width is investigated for various ARs. The results show that as the AR increases, the maximum spreading width of the minor axis increases, whereas that of the major axis shows no significant variation. In the regime of high AR and high impact velocity, liquid fragmentations by three parts are observed during bouncing. These fragmentations are discussed in this work. The hydrodynamic features of ellipsoidal drop impact will help understand bouncing control on non-wetting surfaces for several applications, such as self-cleaning and spray cooling.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2020.07a
• /
• pp.167-168
• /
• 2020

본 연구는 학업중단청소년 패널조사 5차년도 조사(2017년) 데이터를 활용하여 학업중단 청소년의 진로불안이 우울에 영향을 미치는 과정에서 외적 보호요인으로 작용하는 사회적 관계(부모애착, 또래애착)와 내적 보호요인으로 작용하는 자아탄력성의 매개효과를 검증하고자 한다.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.7
• /
• pp.530-532
• /
• 1999

A new lateral device entitled SB-DCEST(segmented p-base dual-channel emitter switched thyristor), which suppresses the snapback is proposed and successfully fabricated. The proposed device effectively suppressed the snapback phenomenon by employing the gigh resistance in self-aligned segmented p-base when compared with the conventional DCEST. The experimental results show that the SB-DCEST has the low forward voltage drop of 4.3 V at anode current of $150 A/cm^2$ with the eliminated snap-back regime, while conventional DCEST exhibits higher forward voltage drop of 5.3 V.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.02a
• /
• pp.314-315
• /
• 2003

링형 네트워크는 자연재해나 사고로 인한 시스템 절체 복구 기능을 수행 할 수 있어서 기간 망에서 오랫동안 사용되어왔다. 최근 WDM을 이용한 링형 네크워크에 대한 관심이 고조되면서, 특히 1심을 이용한 self-healing 또는 restoration 등에 관한 연구가 활발히 이루어지고 있다. 하지만 절체 복구 기능을 수행할 수 있는 소자들이 너무 고가이고, 시스템이 복잡해지는 문제점이 있다. 본 논문에서는 저가의 광 Add／Drop Mux, 리던던시(Redundancy)미디어 컨버터 칩과 이중 광모듈 을 사용한 복구 기능을 가지는 단심 양방향 링형 WDM-EPON 시스템을 구현하였다. (중략)

• Journal of Aerospace System Engineering
• /
• v.2 no.2
• /
• pp.8-13
• /
• 2008

The fuel tank systems of fixed wing and rotary wing aircrafts require the self-sealing and crash-worthiness for their survivability. For these requirements, the flexible composite fuel tank is generally used. In this study, the drop and penetration performance of a fuel tank is investigated. The FE simulation includes the drop and penetration test of a fuel tank using MSC.DYTRAN. MSC.DYTRAN can provide the fluid-structure modeling of these test from Euler and Lagrange grids. Using MSC.DYTRAN, the finite modeling of the test cube of the flexible fuel tank and its FE simulation are performed for various environments. The simulation results can show if the test cube satisfies the performance requirements of the fuel tank.

• Journal of the Korea Safety Management & Science
• /
• v.10 no.4
• /
• pp.145-152
• /
• 2008

According to the Korea Agency for Technology and Standards under the Commerce Ministry, OLED device's lifetime is defined 50% drop of luminance. OLED device is self-emitting operating device, that means it becomes different color between pixels under using environment. That's reason of the different luminance drop ratio & chromaticity coordinates shift ratio with time. The problem is there is not recovered after luminance drop and color shift. We can recognize the difference of color as image sticking. First we studied when human recognize the difference of color and second we apply the method of OLED device's lifetime test that's able to check different color between pixels.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.1286-1288
• /
• 1996

An add/drop control chip for SDH transmission system has been designed in AT&T 0.5um CMOS ORCA FPGA. This device plays an important role in achieving self-healing ring operation which protects against failure. After this device receives each 24-ch AU-3 signals from the west, east, and add parts, it outputs each 24-ch switched signals through the control data of system control port. This device consists of eight sub-part such west/east transmitting part, west/east receiving part, add/drop control part, AIS control part, and CPU interface part. The designed device is capable to ring networks as well as linear networks.