• Journal of Embryo Transfer
• /
• v.25 no.1
• /
• pp.57-66
• /
• 2010

The conception rate of cow is a major factor in farm management. The environment of farm and management of cow are the best influencing factors on conception rate, and the fertility of bull is the second influencing factor. In Hanwoo bull, however, the informations limited to performance and carcass traits have been offered to Hanwoo farmer. Therefore, this study analysed the estimated relative conception rates (ERCR) for estimation of fertility of bulls, using the 8,892 mating data with 116 heads of prove bull to produce progeny. Mean of least square means of conception rate after first insemination was 50.95% in bull herds. On the standard of this mean, ERCRs after first insemination of each bull were analysed. Values ranged from -26.1% to +21.0%, the difference was 47.1%. Among 116 heads of bull analysed, KPN582 showed the highest ERCR as 21.0%, KPN550 (18.3%), KPN656 (16.7%), KPN632 (15.8%), KPN690 (14.9%) were gone behind, but KPN621 was the lowest as -26.1%, KPN680 (-21.3%), KPN674 (-16.2%), KPN569 (-15.9%), KPN699 (-14.9%) were succeeded. If ERCRs of Hanwoo bull will be offered to Hanwoo farmer, it will be worthwhile.

• Journal of Korean Society of Rural Planning
• /
• v.11 no.4 s.29
• /
• pp.99-108
• /
• 2005

In this study, thirteen villages in Chonnam province were selected as case study sites and the spatial distribution of the facilities in the villages was examined to provide basic information fur the establishment of rural plans. According to the questionnaire survey, various problem such as environmental pollution, position, scene, management etc. was brought owing to cattle shed, and dissension was more or less seen by scale of facilities, management of facilities and waste, regional factor(stock farming management condition, life style and attitude of inhabitants) and topographical factor (height, position physical aspect of a mountain, distance with water resources etc.) etc.. The facilities could be classified into 6 types based on the their spatial locations: 1) Type 1, facilities located at the waterside; 2) Type 2, facilities located at the entrance of village; 3) Type 3 facilities, scattered in the residential area: 4) Type 4 facilities, collectivized in village; 5) Type 5 facilities, adjoining village; and 6) Type 6 facilities, scattered irregularly inside and outside of village. Based on the classification, possible implementations for the reduction of environmental impacts were suggested. The results of this study could be used as an example of study on the distribution, classification, and rearrangement of environment-impacting facilities in rural areas for improvement of their roles in providing amenity resources.

• Korean Journal of Construction Engineering and Management
• /
• v.9 no.6
• /
• pp.156-163
• /
• 2008

Recently, Construction market is contracted by economic slump and regulation. As the solution of this plan, construction productivity is gathering strength. However, the study on the productivity in construction section is insufficient until now. Construction section has many factor about productivity. The point of this study, we analysis the factor of construction productivity improvement and relationship with system thinking. And we show the strategy of construction productivity improvement.

• Anxiety and mood
• /
• v.13 no.1
• /
• pp.17-24
• /
• 2017

Objective : The purpose of this study was to investigate the effectiveness of the mental health improvement program in Korean firefighters. Methods : A total of 502 firefighters working at Daegu, Ulsan and Gumi participated in the mental health improvement program for an 8-week period. The program included evaluation and counseling as well as psychoeducation for mental health awareness. Subjects were divided to two groups including the PTSD high risk group and PTSD non-high risk group. Results : The program resulted in a significant decrease in mean scores of depression and insomnia for all firefighters. PTSD high risk group showed a significantly higher level of depression, anxiety, and insomnia. Multiple logistic regression analysis with PTSD high risk group as a dependent variable indicated that moderate depression was a high-risk factor for PTSD in firefighters, as compared to no depression ; in addition, subthreshold and moderate insomnia was another risk factor. Conclusion : The evaluation and management of psychopathologies including depression and insomnia associated with traumatic events can be helpful to improve the mental health of firefighters.

• The KSFM Journal of Fluid Machinery
• /
• v.13 no.4
• /
• pp.37-43
• /
• 2010

The purpose of this study is not only to investigate the effects of air layer in the turbine chamber on the performance and internal flow of the cross-flow turbine, but also to suggest a newly developed air supply method. Field test is performed in order to measure the output power of the turbine by a new air supply method. CFD analysis on the performance and internal flow of the turbine is conducted by an unsteady state calculation using a two-phase flow model in order to embody the air layer effect on the turbine performance effectively. The result shows that air layer effect on the performance of the turbine is considerable. The air layer located in the turbine runner passage plays the role of preventing a shock loss at the runner axis and suppressing a recirculation flow in the runner. The location of air suction hole on the chamber wall is very important factor for the performance improvement. Moreover, the ratio between air from suction pipe and water from turbine inlet is also significant factor of the turbine performance.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.1
• /
• pp.196-202
• /
• 2004

The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on adopting residual stress(in this thesis). The compressive residual stress was imposed on the surface according to each shot velocity(57, 70, 83, 96 m/sec) based on Shot-peening, which is the method of improving fatigue life and strength. By using the methods mentioned above, the following conclusions have been drawn. 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. And in stage I, ΔKth, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

• Journal of the Korean Institute of Rural Architecture
• /
• v.16 no.3
• /
• pp.19-26
• /
• 2014

This study aims to examine residents' satisfaction and behavioral condition at the commercial street of Historic and Cultural Environmental Districts in Gyeongju. To achieve this, the study relied on empirical study method and additionally, present condition survey was performed with a user interview. residents' satisfaction and preferences analysis was conducted to figure out present conditions and improvements. This work has completed a total analysis of the architectural characteristics and street factors among various factors which influence residents' satisfaction level including physical street equipments and street view factors which are main contents of previous studies and street improvement project. Using statistical analysis, each factor's significance was verified quantitatively. Accordingly, this study presents prior consideration points before planning the commercial street improvement project and the region development project.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.556-560
• /
• 2001

In this paper, a soft-switching discontinuous mode (DCM) power factor corrected (PFC) converter is analyzed by applying the double Fourier series expansion. It is found that the fundamental component and higher-order harmonics included in the input current waveform are obtained by the Fourier series expansion of the mean value of the inductor current. From the theoretical analysis, a new method removing the distortion of the input current waveform is proposed. In spite of an open loop system, the proposed method makes a great improvement of the total harmonic distortion even if the ratio of output voltage to input voltage is very low.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.5
• /
• pp.845-850
• /
• 2017

In this thesis, various solutions through four different cases have been sought for an efficiency improvement of the bidirectional LDC for vehicles. For example, it analyzed the reduction factor of the channel resistance and applied the optimum MOSFET applied to the system, and found and improved the efficiency reduction factor of the transformer. As a result, the average efficiency of the developed LDC could be improved from 85% to 94.7%.

• Journal of Advanced Marine Engineering and Technology
• /
• v.29 no.7
• /
• pp.744-749
• /
• 2005

This paper describes the performance improvement of power control system of magnetron (MGT) for microwave oven. The MGT is used extensively in household microwave oven and industrial microwave heating devices, and is operated by 3.0[kV] $\∼$5.0[kV] dc high voltage. The proposed power supply is consisted of a bridge rectifier, step-up converter(SUC) and its controller, half bridge inverter(HBI) and its controller, and full wave double voltage rectifier(DVR). In the proposed system, a good power factor can be obtained by the SUC' switching method that the inductor current waveforms follows that of the rectified voltage, and a line input power can be controlled to a range of 17.5[$\%$] by duty ratio (DR) adjustment of the HBI.