• International Journal of Automotive Technology
• /
• v.7 no.1
• /
• pp.69-74
• /
• 2006

Residual stresses are introduced in aluminum cylinder head during quenching at the end of the T6 heat treatment process. Tensile residual stress resulted from quenching is detrimental to fatigue behavior of a cylinder head when it is overlapped with stresses of engine operation load. Quenching simulation has been performed to assess the distribution of residual stress in the cylinder head. Analysis revealed that in-homogeneous temperature distribution led to high tensile residual stress at the foot of the long intake port, where high stresses of engine operation load are expected. Measurements of residual stress have been followed and compared with the calculated results. Results successfully proved that high tensile residual stress, which was large enough to accelerate fatigue failure of the cylinder head, are formed during quenching process at the end of heat treatment at the same critical position. Effect of quenching parameters on the distribution of residual stress in cylinder head has been investigated by choosing different combination of heat treatment parameters. It was demonstrated that changes of quenching parameters led to more homogeneous temperature distribution during cooling and could reduce tensile residual stress at the critical region of the cylinder head used in this study.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.1
• /
• pp.80-89
• /
• 1998

The residual gas in an spark-ignition engine is one of important factors on emissions and performance such as combustion stability. With high residual gas fractions, flame speed and maximum combustion temperature are decreased and these are deeply related with combustion stability especially at idle and NOx emission at relatively high engine load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating parameters. In the present study, the quantitative measurement technique of residual gas fraction was studied by using Fast Response Flame Ionization Detector(FRFID). The measuring technique and model for estimation of residual gas fraction were reported in this paper. By the assuming that the raw signal from FRFID saturates with the same slope for firing and misfiring cycle, in-cylinder hydrocarbon(HC) concentration can be estimated. Residual gas fraction can be obtained from the in-cylinder HC concentration measured at firing and motoring condition. The developed measurement and calibration procedure were applied to the limited engine operating and design condition such as intake manifold pressure and valve overlap. The results show relevant trends by comparing those from previous studies.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.25 no.4
• /
• pp.253-257
• /
• 2016

The effects of re-peening on the compressive residual stress and fatigue life of Al7075-T6 were investigated. The compressive residual stress induced on the surface of components by shot peening is known to increase the fatigue life. However, the fatigue load relaxes the compressive residual stress of components. Re-peening is a technique to again induce the relaxed compressive residual stress and increase the total fatigue life of components. In this study, the re-peening process was applied to fatigue-loaded specimens. The compressive residual stress and fatigue life were examined for re-peened specimens with fatigue ratios of 30%, 50%, and 70%. The results showed that the compressive residual stress of the specimens was relaxed under the fatigue load. The re-peening process significantly increases the compressive residual stress and total fatigue life.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.10
• /
• pp.4297-4302
• /
• 2015

Background: To evaluate HPV testing by Hybrid Capture II (HCII) in conjunction with cytology in detecting the residual/recurrence disease after treatment of high-grade cervical intraepithelial neoplasia (CIN II-III) with loop electrosurgical excision procedure (LEEP). Materials and Methods: A retrospective review of 158 patients with histologically confirmed CIN II-III who underwent LEEP between January 2011 and October 2012 was conducted. Post-treatment control was scheduled at the 3rd, 6th, 12th and 18th month. All patients were followed up by Pap smear and HR-HPV genotype and viral load testing. Results: Pre-treatment, HR-HPV DNA, was detected in all specimens of the patients. At follow-up, 25 patients were diagnosed as the residual/recurrent disease during the FU visit, among whom, 16 patients with positive margin: 13 patients (52%) with HR-HPV DNA+/cytology+, 2 patients (8%) with HR-HPV DNA+/cytology-, 1 patient (4%) with cytology+/HR-HPV DNA-; 9 patients with clean margin - 5 patients (55.6%) with HR-HPV DNA+/cytology+; 2 patients (22.2%) with HRHPV DNA+/cytology-, 2 patients (22.2%) with cytology+/HR-HPV DNA-. None of them persisting HR-HPV DNA-/cytology-with positive or negative margin was identified as the residual/recurrent disease. The majority of residual/recurrent disease was detected at the 12th and 18th month FU, and there was almost no difference in the sensitivity and negative predictive value (NPV) between at the 3rd month and the 6th month FU visits. 14 residual/recurrence disease (14/46:30.4%) had pre-treatment high viral load (>5 000 RUL/PC) and 11 (11/112, 9.8%) with pre-treatment low viral load, P<0.05. Conclusions: (1) The persistence HR-HPV DNA is the root cause of the residual/recurrent disease for the women treated for high-grade CIN; the pre-treatment viral load and margin can be seen as the predictor. (2) The FU visit beginning at the 6th month post-treatment and lasting at least 24 months with the combination of cytology and HPV testing. (3) Patients with high pre-treatment HPV load, which is considered as one risk of developing the residual/recurrent disease, should be paid more attention (especially above 500RUL/PC) to by clinicians.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.4
• /
• pp.26-33
• /
• 2000

In-cylinde flow and mixture formation are key contributors to both idle stability and combustion stability at part load condition in SI engine. The real time measurements of air-fuel ration and in- cylinder residual gas fraction are particularly important to obtain a better understanding of the mechanisms for combustion and emissions especially during cold start and throttle transient condition. This paper reports the cycle resolved measurements of residual gas fraction and equivalence ration near speak plug with value timing change and their effects on combustion characteristics at part load. The results showed that the effect of intake value opening on the residual gas fraction was smaller than that of exhaust valve closing because of the decreases of exhaust gas reverse flow from exhaust port. The variation of equivalence ratio near spark plug increased with the increase of value overlap and it closely related with heat release rate and combustion stability

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.279-282
• /
• 2005

A real-time measurement and control system was developed, This system is used for nurses at hospitals to check the residual quantity and changing time of Ringer's solution in nurses' room. Load Cell is utilized as a sensor to check the residual quantity of Ringer's solution, This Load Cell detects the physical changes of Ringer's solution and transfers electronic signal to the amplifier. Amplified analog signal is converted into digital signal by NO converter. Developed Embedded system, which computes these data with microprocess(8052) then makes it possible to monitor the residual quantity of Ringer's solution real-time on a server computer. A Checking system on Residual Quantity of Ringer's Solution Using Load cell cut costs using a simple design for a circuit

• Geomechanics and Engineering
• /
• v.16 no.2
• /
• pp.113-124
• /
• 2018

Under repeated loading, the residual stresses within the subgrade and subsoil can accelerate the deformation of the road structures. In this paper, a series of laboratory cyclic loading model tests and small-scale model tests were conducted to investigate the dynamic stress response within soils under different loading conditions. The experimental results showed that a dynamic stress accumulation effect occurred if the soil showed cumulative deformation: (1) the residual stress increased and accumulated with an increasing number of loading cycles, and (2) the residual stress was superimposed on the stress response of the subsequent loading cycles, inducing a greater peak stress response. There are two conditions that must be met for the dynamic stress accumulation effect to occur. A threshold state exists only if the external load exceeds the cyclic threshold stress. Then, the stress accumulation effect occurs. A higher loading frequency results in a higher rate of increase for the residual stress. In addition to the superposition of the increasing residual stress, soil densification might contribute to the increasing peak stress during cyclic loading. An increase in soil stiffness and a decrease in dissipative energy induce a greater stress transmission within the material.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.10
• /
• pp.81-88
• /
• 2012

Surge protective devices(SPDs) are widely used as a most effective means protecting the electrical and electronic equipment against overvoltages such as lightning and switching surges. When installing SPDs, it is essential that the voltage protection level provided by SPDs should be lower than the withstand voltage of the equipment being protected. But even the proper selection of SPDs are achieved, the voltage at the equipment terminal may be higher than the residual voltage of SPD due to the reflection and oscillation phenomena. This paper was focused on the investigations of the conditions for which the equipment is protected by an SPD taking into account the influences of the protective distance and type of load. The protective effects of SPD with voltage-limiting component were analyzed as functions of types of load and protective distance between the SPD and load. As a result, in the cases of long protective distances, capacitive loads and loads with high resistance, the voltage at the load terminal was significantly higher than the residual voltage of SPD. It was found that the proper installation of SPDs should be carried out by taking into account the protective distance and type of load to achieve reliable protection of electronic equipments against surges.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.8
• /
• pp.35-47
• /
• 2020

For permanent anchors used for slope reinforcement, bearing capacity and durability should be secured during the period of use. However, according to recent domestic and foreign studies, phenomena such as tension fractures, damage to anchorages, deformation and damage to slope and reduction of residual load over time have been reported along the long-term behavior of the anchors. These problems are expected to increase in the future, which will inevitably lead to problems such as increasing maintenance costs and relevant facility collapse. It is necessary to improve maintenance procedures and methods of ground anchors more practically. In this study, the problems and limitations of domestic maintenance methods were analyzed by conducting a literature study, and the measurement data of load cells installed on the install ground anchors were analyzed to determine the change in the residual load with regard to the elapsed date of the anchors. Based on the results, the effect of the construction conditions of anchors and the soil compositions on the increase and decrease of load were identified.

• International Journal of Korean Welding Society
• /
• v.5 no.1
• /
• pp.60-65
• /
• 2005

In the field of welding the mechanical behavior of a welded structure under consideration may be predicted via heat transfer and welding residual stress analysis. Usually such numerical analyses are limited to small regular mesh models or test specimens. Nevertheless, there is very few strength assessment of the whole structure that includes the effect of welded residual stress. The present work is based on the specialized finite element codes for the calculation of nonlinear heat transfer details and residual stress including the external load on the welded RHS (Rectangular Hollow Section) T-joint connections of the whole structure. First the thermal history of the combined fillet and butt-welded T-joint equal width cold-formed RHS are calculated using nonlinear finite element analysis (FEA) considering the quarter model of the joint. Then using this thermal history the residual stress around the joints has been evaluated. To validity the FEA result, the calculated residual stresses were compared with the available experimental results. The residual stress obtained from the quarter model is mapped to the full model and then to the whole structure model using FEM codes. The results from the FEM codes were exported to the commercial package for visualization and further analysis applying loads and boundary conditions on the whole structure. The residual stress redistribution along with the external applied load is examined computationally.