• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.369-374
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• 2000

This study was conducted to investigate the seismic behavior assessment of circlular-tied bridge piers, particularly with regard to assessing the displacement ductility. The experimental variables of bridge piers test consisted of transverse steel details, amount and spacing different axial load levels etc. The test results indicated that reinforcement concrete bridge piers with confinement steel by the code specification exhibited sufficient ductile behavior and seismic performance. Aldo, it is found that current seismic design code specification of confinement steel requirements may be revised.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.257-260
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• 2001

As today's network infrastructure continues to grow and DiffServ IP networks ate now available to provide various levels of flexible QoS services. DiffServ guarantees good scalability but shows dynamic QoS dependent on network traffic loads. Therefore, in this paper, we investigate the dynamics of DiffSev QoS and present analytical model to estimate the allowable traffic load under the given network conditions.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.274-285
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• 1998

Increasing flexibility and lightness of recently built high-rise buildings make the structures susceptible to loads such as earthquakes and winds. Therefore, higher performance vibration control systems to reduce the vibration levels are demanded more than any time in the past. One of typical active vibration control systems is the active mass damper(AMD). In this paper, an active vibration control system consisting of small shaking table, building model, sensors, signal processing board and AMD is constructed. The dynamic characteristics of these individual systems are investigated through the experimental study. The performance of the active vibration control system is verified through harmonic resonant load excitation on building model.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.297-304
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• 1997

Sphere anemometry technique is re-visited for low gas velocity measurements during full-scale fire tests. This technique has the advantage of requiring only one channel per sphere for data acquisition, in addition to being cheap and rugged, The results indicate that the technique is useful for small fuel load burns with low radiation levels. For large fuel loads, the usefulness is up to sprinkler activation temperatures.

• Journal of Animal Science and Technology
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• 제44권2호
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• pp.261-270
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• 2002

This study was executed to elucidate the degree of satisfaction with working environment and the factors affecting it for workers who are engaged in the composting plants with livestock manure in the Han-river watershed. As an evaluation on site, we applied the self-administered questionaire including general characteristics, working conditions, degree of satisfaction with working environment, and degree of satisfaction with working condition. Simultaneously, we analysed the exposure levels of odor (ammonia, hydrogen sulfide, and odor intensity) in the boundary area of plants. As a result of the study, health condition, odor, work load, dust, and smoking were proved to be the main factors affecting the degree of satisfaction with working environment for workers who are employed in the composting plants with livestock manure in the Han-river watershed. Of them, it was investigated that health condition, odor, and work load accounted for 61.3% of the total degree of satisfaction with working environment and health condition(p$<$0.01), odor(p$<$0.05), work load(p$<$0.05), and dust(p$<$0.05) were statistically significant. It was concluded that the degree of satisfaction with working environment was high for the workers who had good health status and low for the workers who had the relatively considerable work load and were often exposed to odor and dust. Therefore, to increase the degree of satisfaction with working environment for workers who are engaged in the composting plants with livestock manure, the measures that can reduce the exposure levels of odor and dust emitting from the composting plant with livestock manure should be improved.

• Journal of the Korea Concrete Institute
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• 제19권5호
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• pp.529-537
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• 2007

The purpose of this study is to discuss how strength and ductility of each system in low-rise reinforced concrete buildings composed of extremely brittle, shear and flexural failure lateral-load resisting systems have influence on seismic capacities of the overall system, which is based on nonlinear seismic response analyses of single-degree-of-freedom structural systems. In order to simulate the triple lateral-load resisting system, structures are idealized as a parallel combination of two modified origin-oriented hysteretic models and a degrading trilinear hysteretic model that fail primarily in extremely brittle, shear and flexure, respectively. Stiffness properties of three models are varied in terms of story shear coefficients, and structures are subjected to various ground motion components. By analyzing these systems, interaction curves of demand strengths of the triple system for various levels of ductility factors are finally derived for practical purposes. The result indicates that demand strength levels derived can be used as a basic information for seismic evaluation and design criteria of low-rise reinforced concrete buildings having the triple lateral-load resisting system.

• Pediatric Infection and Vaccine
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• 제24권1호
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• pp.44-53
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• 2017

Purpose: The aim of this study was to investigate the risk factors for posttransplant lymphoproliferative disorder (PTLD) and to evaluate the association between Epstein-Barr viral load and the development of PTLD in pediatric heart transplant recipients. Methods: We reviewed children aged <18 years who underwent heart transplantation and quantitative analysis of blood Epstein-Barr virus (EBV) viremia at our institute from January 2006 to March 2015. Clinical characteristics and EBV viral loads were compared according to the presence of PTLD. Results: Over 9 consecutive years, a total of 40 heart transplant recipients, were included. Among 28 children with available EBV viral load measurements, seven patients (25%) had EBV viremia only defined as at least one time of ${\geq}457copies/mL$. PTLD occurred in three recipients (7.5%) 4.3, 6.3, and 17.0 months after transplant and all PTLD cases had preceding EBV viremia. The median age at transplant was 5.3 years (range, 0.5 to 6.0 years) in the PTLD group, compared with 11.9 years (range, 0.3 to 17.8 years) in the non-PTLD group (P=0.021). The median values of the peak EBV levels in the PTLD group were 3,452,170 copies/mL (range, 46,750 to 7,622,910 copies/mL); the peak EBV levels in the non-PTLD group were 3,112 copies/mL (range, 2,250 to 103,000 copies/mL). Conclusions: Younger age at transplant and presence of EBV viremia were associated with the development of PTLD in pediatric heart transplant recipients. A prospective study will be required to determine the blood EBV load for predicting the development of PTLD in these patients.

• Journal of Korean Neurosurgical Society
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• 제58권5호
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• pp.412-418
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• 2015

Objective : To investigate the effects of posterior implant rigidity on spinal kinematics at adjacent levels by utilizing a cadaveric spine model with simulated physiological loading. Methods : Five human lumbar spinal specimens (L3 to S1) were obtained and checked for abnormalities. The fresh specimens were stripped of muscle tissue, with care taken to preserve the spinal ligaments and facet joints. Pedicle screws were implanted in the L4 and L5 vertebrae of each specimen. Specimens were tested under 0 N and 400 N axial loading. Five different posterior rods of various elastic moduli (intact, rubber, low-density polyethylene, aluminum, and titanium) were tested. Segmental range of motion (ROM), center of rotation (COR) and intervertebral disc pressure were investigated. Results : As the rigidity of the posterior rods increased, both the segmental ROM and disc pressure at L4-5 decreased, while those values increased at adjacent levels. Implant stiffness saturation was evident, as the ROM and disc pressure were only marginally increased beyond an implant stiffness of aluminum. Since the disc pressures of adjacent levels were increased by the axial loading, it was shown that the rigidity of the implants influenced the load sharing between the implant and the spinal column. The segmental CORs at the adjacent disc levels translated anteriorly and inferiorly as rigidity of the device increased. Conclusion : These biomechanical findings indicate that the rigidity of the dynamic stabilization implant and physiological loading play significant roles on spinal kinematics at adjacent disc levels, and will aid in further device development.

• Journal of Bio-Environment Control
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• 제26권2호
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• pp.64-71
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• 2017

The study was performed on the effects of crop load of pear (Pyrus pyrifolia Nakai) trees on shoot growth, reserved nutrients, and fruit production for two years, as well as regrowth of cuttings treated with various cold temperatures in 2012 and 2013. Crop load adjustments included three levels of fruiting; 54 (60%), 90 (100%), and 126 fruits per tree (140%). As increasing crop load from 60% to 140%, water sprout growth decreased, and one-year old shoot resulted in declined concentrations of total carbon, macro-nutrients, and free sugar. The 140% of crop load greatly increased fruit yield of approximately 35 tons per ha in both 2011 and 2012 but slightly reduced weight, size, and soluble solid contents in fruit. However, 140% of crop load increased annual production income to approximately over 10 million won compared to the 60% and 100% of crop load. Germination rates in the cuttings did not rapidly decrease up to $-20^{\circ}C$ in a growth chamber condition. The 140% of crop load decreased germination rates less than 70% of cuttings grown under $-30^{\circ}C$. Amounts of electrolyte leakage in the cuttings under various cold temperatures were not significantly different among the adjustment of crop load.

• Journal of the Korea institute for structural maintenance and inspection
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• 제23권2호
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• pp.130-134
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• 2019

In this paper, a laser-based non-contact load cell is newly developed for measuring forces in prestressed concrete tendons. First, alumina particles have been sprayed onto an empty load cell which has no strain gauges on it, and the layer has been used as a passive stress sensor. Then, the spectral shifts in fluorescence spectroscopy have been measured using a laser-based spectroscopic system under various force levels, and it has been found that the relation of applied force and spectral shift is linear in a lab-scale test. To validate the field applicability of the customized load cell, a full-scale prestressed concrete specimen has been constructed in a yard. During the field test, it was, however, found that the coating surface has irregular stress distribution. Therefore, the location of a probe has to be fixed onto the customized load cell for using the coating layer as a passive stress sensor. So, a prototype customized load cell has been manufactured, which consists of a probe mount on its casing. Then, by performing lab-scale uniaxial compression tests with the prototype load cell, a linear relation between compression stress and spectrum shift at a specific point where laser light had been illuminated has been detected. Thus, it has a high possibility to use the prototype load cell as a force sensor of prestressed concrete tendons.