• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.916-922
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• 2001

A mechanical face seal is a tribo-element intended to control leakage of working fluid at the interface between a rotating shaft and its housing. Leakage of working fluid decreases drastically as the clearance of the mating seal faces gets smaller. But the very small seal clearance results in an increased reduction of seal life because of high wear and heat generation. Therefore, in the design of mechanical face seals a compromise between low leakage and acceptable seal life is important, and it presents a difficult and practical design problem. A fluid film or sealing dam geometry of the seal clearance affects seal lubrication performance very much, and thereby it is one of the main design considerations. In this study the Reynolds equation for the sealing dam of mechanical face seals is numerically analyzed, using the Galerkin finite element method, which is readily applied to various seal geometries. Film pressures of the sealing dam are analyzed, including the effects of the seal face coning and tilt. Then, lubrication performances of the seals, such as opening forces, restoring moments, leakage, and dynamic coefficients, are calculated, and they are compared to the results obtained by the narrow seal approximation.

• Journal of Animal Science and Technology
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• v.45 no.6
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• pp.1067-1078
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• 2003

This study was designed to determine the effect of gestation housing and parity on the farrowing performance and behaviour of sows during pregnancy, farrowing and lactation periods. Total 18 Duroc sows were randomly assigned after 4 weeks of gestation to either an individual gestation stall or a groups of three with pen gestation system for three parities(1st, 2nd${\sim}$3rd, and 4th${\sim}$5th). Approximately 7 days before predicted farrowing date, sows were transferred to farrowing crates where they remained until 21 days post-partum. Behaviour was recorded on day 60 and 90 of pregnancy for 24 hours, on day of farrowing for farrowing duration and on day 10 of lactation for 2.5 hours in the farrowing crate. The results obtained from this study were summarized as follows: On 60 and 90 day of pregnancy, all sows in both groups made attempts for ventral lying more than for other postures. Sows in the group gestation pen spent more time on walking than those in individual gestation stall(p<0.01); however, the group housed sows were spent less time on drinking than the individually housed sows(p<0.01). There was no significant difference between gestation housings in the occurrence of stereotypy of pregnant sows. On day 60 of pregnancy, sows in the individual gestation stall showed the highest frequency of vacuum chewing and head weaving. However, floor licking and bar licking behaviours were highest in day 90 pregnant sows individually housed. The sows individually housed during the gestation period spent more time on sitting and eating on the day of farrowing in the farrowing crate than the sows group housed. On day 10 of lactation in the farrowing crate, the group housed sows during the gestation period made significantly more attempts for ventral lying than sows individually housed. In conclusion, the occurrence of stereotypy of sows during the gestation and lactation did not differ between gestation housings and farrowing performance of sows during the gestation period was not affected by gestation housing. Thus, the group housing for pregnant sows is a feasible means to improve welfare of sows and to increase the normal behaviour of sows.

• KIEAE Journal
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• v.10 no.4
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• pp.19-28
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• 2010

As design tools, building performance certification systems can be applied to provide adequate guidelines on design process to create environment-friendly buildings. Domestic certification systems of residential building took effect by doing supply to designers and contractors from affiliated organization of governments in the early 2000s. As a result, Building Energy Rating System, Apartment Performance Rating System, Green Homes and other means to promote green designs have been operated. International trends of applying certification systems were started in the early 1990s as forms of LEED in USGBC, BREEAM in BRE, GBTool Canada. These systems aim to evaluate building performance in line with the Climatic Change Convention and realize sustainable building design. In 2009, residential buildings accounted for the largest portion of the internal real estate market with 67.9 percent according to the National Statistical Office data. And for 18 years since 1991, apartments among constructed residential buildings have ranked top taking up 77.7% as of 2009. Apartment performance evaluations accordingly are to promote to constitution of improving tenant quality of life, the residential environment and saving energy and resources in the internal building market. The purpose of this study is to compare and analyze valuation bases of each sector in evaluation systems of residential buildings at home and abroad to upgrade current systems through reflecting the characteristics of residential buildings. Implementation of this study basically include comparison of valuation bases and partial analysis on properties of rating systems to suggest requisites for improvement in building performance certification.

• Land and Housing Review
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• v.7 no.3
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• pp.137-145
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• 2016

This study aims to empirically verify the positive impacts of PB(performance-based) HRM on the organizational effectiveness in a public corporation. The independent variables are 'PB staffing', 'PB appraisal', 'PB compensation'. The dependent variables are 'JS(job satisfaction)', 'OC(organizational commitment)'. The results are as follows. 'PB staffing' shows positive impact on both 'JS' and 'OC', but 'PB compensation' doesn't show positive impact on both 'JS' and 'OC'. Also, it is found that both 'PB appraisal' and 'PB compensation' do not show positive impact on 'OC'. 'PB appraisal' shows positive impact on 'JS', though. From the empirical analysis, the positive effects of the PB-HRM on the organizational effectiveness are partially verified. It is thought that these mixed results are originated from the particular situation in which the surveyed corporation is placed. After the merger of the corporation in 2009, even though it has introduced various PB-HRM systems, it has been through a harsh time such as wage freeze and return as measures of business normalization. This organizational situation may influence the verification of effectiveness of the normal PB-HRM.

• Land and Housing Review
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• v.3 no.1
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• pp.89-96
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• 2012

The purpose of this study was to evaluate the applicability of hybrid ventilation system in apartment housings and present a design method to improve the performance of hybrid ventilation system using the CFD simulation. As the object of CFD simulation, a small apartment houses with area of $51m^2$ and $81m^2$ were selected and evaluated. The test hybrid ventilation system are window frame natural air supply & duct exhaust hybrid system(Hybrid 1) and window frame natural air supply & bathroom and livingroom exhaust hybrid ventilation system(Hybrid 2). To evaluate the ventilation efficiency, we used the locations of diffuser installed for each system as the variables through the CFD simulation. In the case of Hybrid 1, the ventilation efficiency of the exhaust duct diffuser located on the inside room was higher rather than the exhaust duct diffuser located on the entrance. In the case of Hybrid 2, the most efficient system was the system that the diffuser connecting the bathroom static pressure fan is installed on the center of the living room. The ventilation efficiency of the Hybrid 2 in the case of $51m^2$ type was more than 20% of the Hybrid 1. But, The ventilation efficiency of the Hybrid 2 in the case of $84m^2$ type was more than 14% of the Hybrid 1. Therefore, to apply the Hybrid ventilation, a study that considers various variable should be conducted.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.43-51
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• 2017

As per current seismic design codes, diagonally reinforced coupling beams are restricted to coupling beams having aspect ratio below 4. However, a grouped diagonally reinforcement detail makes distribution of steel bars in the beam much harder, furthermore it may result in poor construction quality. This paper describes the experimental results of concrete coupling beam reinforced with high-strength steel bars (SD500 & SD600 grades). In order to improve workability for fabricating coupling beams, a headed large diameter steel bar was used in this study. Two full-scale coupling beams were fabricated and tested with variables of reinforcement details and aspect ratio. To reflect real behavior characteristic of the beam coupling shear walls, a rigid steel frame system with linked joints was set on the reaction floor. As a test result, it was noted that cracking and yielding of reinforcement were initially progressed at the coupling beam-to-shear wall joint, and were progressed to the mid-span of the coupling beam, based on the steel strain and failure modes. It was found that the coupling beams have sufficient deformation capacity for drift ratio of shear wall corresponding to the design displacement in FEMA 450-1. In this study, the headed horizontal steel bar was also efficient for coupling beams to exhibit shear performance required by seismic design codes. For detailed design for coupling beam reinforced with high-strength steel, however, research about the effect of variable aspect ratios on the structural behavior of coupling beam is suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.9-20
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• 2019

The number of natural disasters in Korea, such as earthquakes, is increasing. As a result, there is growing need for temporary residences or shelters for disaster conditions. The aim of this study was to produce post-disaster refugees housing differentiated from existing shelters using lightweight composite panels. To accomplish this, the structural performance of lightweight composite panels was validated, and an in-plane shear strength test was conducted according to the ASTM E72 criteria among the performance test methods for panels. As a result of the experiment, the maximum load for each specimen under an in-plane shear load was determined. All the experiments ended with the tear of the panel's skin section. The initial stiffness of the specimens was consistent with that predicted by the calculations. On the other hand, local crushing and tearing, as well as the characteristics of the panel, resulted in a decrease in stiffness and final failure. Specimens with an opening showed a difference in stiffness and strength from the basic experiment. The maximum load and the effective area were found to be proportional. Through this process, the allowable shear stress of the specimens was calculated and the average allowable shear stress was determined. The average ultimate shear stress of the lightweight composite panels was found to be $0.047N/mm^2$, which provides a criterion of judgement that could be used to expect the allowable load of lightweight composite panels.

• Land and Housing Review
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• v.13 no.1
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• pp.141-150
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• 2022

Responding to the increasing demand for research on seismic resistance of structures triggered by a large-scale earthquake in Korea, the Ministry of the Interior and Safety revised the typical application of the existing seismic design standards with the national seismic performance target enhanced. Therefore, in this paper, the dam body of the aged Test-Bed and the penstock with fluid were modeled by the three-dimensional finite element method by introducing several variables. The current seismic design standard law confirmed the safety of the dam structure and penstock against seismic waves. As a result of the 3D finite element analysis, the stress change due to the water impact of the penstock was minimal, and it was confirmed that the effect of the hydraulic pressure was more significant than the water impact in the earthquake situation. When the hydrostatic pressure is in the form of SPH, it was analyzed that the motion of the fluid and the location of stress caused by the earthquake can be effectively represented, and it will be easier to analyze the weak part. As a result of the analysis, which considers penstock's corrosion, the degree of stress dispersion gets smaller because the penstock is embedded in the body. The stress result is minimal, less than 1% of the yield stress of the steel. In addition, although there is a possibility of micro-tensile cracks occurring in the inlet of the dam, it has not been shown to have a significant effect on the stress increa.

• Land and Housing Review
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• v.15 no.3
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• pp.165-175
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• 2024

As living standards improve, the demand for quiet and comfortable environments is increases. However, noise sources are rising due to population growth, urbanization, and industrialization. One solution to this problem is low-noise asphalt pavement, which has fewer installation regulations and can reduce noise at the source. Despite its advantages, there are few evaluation cases and no domestic guidelines for low-noise asphalt pavement. This study aims to evaluate the overall performance of low-noise asphalt pavement on roads in Seoul, focusing on average noise levels, skid resistance, and permeability. Noise measurements were conducted using a digital noise analyzer according to the Ministry of Environment's standards. Results indicated that noise reduction was maintained for 1 to 2 years but decreased over time. Skid resistance, assessed with the British Pendulum Tester, showed excellent performance with values above the standard of 57 in the initial stages after paving. Permeability, evaluated using the KS F 2394 method, was initially effective across all sections but declined over time.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.523-526
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• 2007

In Korea, the construction industry has been growing quantitatively because of its aggressive advances into overseas construction market and the Korean government's housing policy. Moreover, visions and goals such as 'construction industry promotion build up plan' have recently been promoted by the government while new strategic growth focused on competitiveness is gaining interests among the industry. However, there are a few problems in the construction performance. First, the specific performance measurement indicator or skills for the construction industry are hardly found in Korea. Currently, the finance or overall management system in the construction business are used as indicators to measure performances in not only the construction industry but all industries including the manufacturing industry. The government, the industry and universities recognized the need for the performance measurement indicator and skill and have developed and actively studied on them.