• Korean Journal of Agricultural Science
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• v.44 no.2
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• pp.244-253
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• 2017

This study was conducted to investigate the growth performance indices among male commercial crossbred Korean native chickens from hatch to twelve weeks of age. A total of 312 one-day-old male birds were used for 6 groups of the commercial crossbred Korean native chicken within 1 paternal line and 6 maternal lines (1A, 2A, 3A, 4A, 5A, and 6A). The chickens were allocated to 24 battery cages to give 4 replicates per each crossbreed with 13 chickens per cage. Ad-libitum feeding was practiced throughout the experimental period and fresh water was available via nipple drinkers at all times. Body weight and feed intake were measured at two-week interval. Among six crossbreeds, the 2A group had the greatest (p < 0.05) body weight at week 8 and the greatest average daily weight gain in week 6 - 8. However, crossbreed 2A had the lowest viability (p < 0.05) at week 8 of all crossbreed groups as well as higher uniformity (p > 0.05) at week 2 than the others. No difference (p < 0.05) was found in any crossbreed Korean native chicken's growth performance indices including body weight, average daily gain, average daily feed intake, feed efficiency, uniformity, and viability after week 8. With this in mind, crossbreed 2A had greater bodyweight, average daily gain, average feed intake, and feed efficiency than the other Korean native chickens 84 days after hatch, although they had lower uniformity and viability than the others.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.4
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• pp.299-311
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• 1994

The new course distances of a ship are one of the important factors of the safety handling as the indices to indicate directly her abilities of course alteration. Recently, International Maritime Organization (IMO) exhorts that all vessels should use maneuvering booklets in which are drawn the curves of new course distances obtained from the test of measuring them and noted other maneuvering performance standard in various navigation conditions. This paper describes the method to calculate many new course distances for many rudder angles by turning circle test without observation or using other calculating methods. The main results are as follows: 1) The mean difference of the distances between two new course distances by the turning circle test and heading test of the experimental ship was about 7.7% vaules of the ones by the heading test. when her altering angles were $48^{\circ}$, $63^{\circ}$and $70^{\circ}$, using the rudder angle of $35^{\circ}$ . These new course distances were therefore found to be small in difference of those. 2) The mean difference of the distance between two new course distances by the turning circle test and the maneuvering indices of the experimental ship was about 4.5% values of the ones by the maneuvering indices, when her altering angles were $48^{\circ}$, $63^{\circ}$and $70^{\circ}$, using the rudder angle of $35^{\circ}$, these new course distances were therefore found to be small in difference of those. 3) The mean difference of the distance between two new course distances by the turning circle test and the observation of the experimental ship was about 6.1% values of the ones by the observation, when her altering angles were $48^{\circ}$, $63^{\circ}$and $70^{\circ}$, using the rudder angle of $35^{\circ}$. These new course distances were therefore found to be small in difference of those. 4) It is confirmed that many new course distances for many angles can be calculated easily by using the method of ship's simple turning circle test, without observation or using the maneuvering indices and heading test method. 5) It is considered to be helpful for the safety of ship handling to draw curves of new course distances by turning circle test and $\phi_4$ - $\phi_2 by heading test, and utilize them at sea.

• Structural Engineering and Mechanics
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• v.65 no.6
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• pp.751-760
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• 2018

Damages in concrete structures due to aging and other factors could be a serious and immense matter. Making the best selection of the most viable and practical repairing and strengthening techniques are relatively difficult tasks using traditional methods of structural analyses. This is due to the fact that the traditional methods used for assessing aging structure are not fully capable when considering the randomness in strength, loads and cost. This paper presents a reliability-based methodology for assessing reinforced concrete members. The methodology of this study is based on probabilistic analysis, using statistics of the random variables in the performance function equations. Principles of reliability updating are used in the assessment process, as new information is taken into account and combined with prior probabilistic models. The methodology can result in a reliability index ${\beta}$ that can be used to assess the structural component by comparing its value with a standard value. In addition, these methods result in partial safety factor values that can be used for the purpose of strengthening the R/C elements of the existing structure. Calculations and computations of the reliability indices and the partial safety factors values are conducted using the First-order Reliability Method and Monte Carlo simulation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.189-199
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• 2002

This study is intended to propose a systematic procedure for the development of the conditional assessment based on the safety of structures and the cost effective performance criteria for designing and upgrading of bridge structures. As a result, a set of cost function models for a life cycle cost analysis of bridge structures is proposed and thus the expected total life cycle costs (ETLCC) including initial (design, testing and construction) costs and direct/indirect damage costs considering repair and replacement costs, human losses and property damage costs, road user costs, and indirect regional economic losses costs. Also, the optimum safety indices are presented based on the expected total cost minimization function using only three parameters of the failure cost to the initial cost (${\tau}$), the extent of increased initial cost by improvement of safety (${\nu}$) and the order of an initial cost function (n). Through the enough numerical invetigations, we can positively conclude that the proposed optimum design procedure for bridge structures based on the ETLCC will lead to more rational, economical and safer design.

• Advances in concrete construction
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• v.13 no.2
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• pp.191-198
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• 2022

FIB is introduced as the sole guideline for the design purpose that results in a practical relationship for the torsional capacity of concrete beams strengthened with carbon fiber-reinforced polymer (CFRP). This study applies first-order reliability method to assess the reliability evaluation of the torsional capacity of CFRP-strengthened beams on the basis of FIB guidelines. In terms of steel reinforcement losses, this study applies a corrosion model to investigate the ceaseless deterioration of the existing structure. Hence, the average of reliability indices varies between 2.68 and 2.80, indicating the reliability viewpoint of the design methodologies. The average values are somehow low compared to the target values of reliability (3.0 or 3.5) applied in the calibration stage of the FIB guideline. In this way, the partial safety factors may change in the forthcoming guideline revisions. For this aim, the reliability of strengthening ratio was applied to assess the variation in the average value of the reliability index with different partial safety factors. The performance of parametric study for the factor proved that minimum values of 1.60 and 2.32 are required for target values of reliability (3.0 and 3.5), respectively.

• Steel and Composite Structures
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• v.46 no.5
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• pp.673-687
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• 2023

In this study, the weight and the connections type layout of low-rise eccentrically braced frame (EBF) have been optimized based on performance-based design method. For this purpose, two objective functions were defined based on two different aspects on rigid connections, in one of which minimization and in the other one, maximization of the number of rigid connections was considered. These two objective functions seek to increase the area under the pushover curve, in addition to the reduction of the weight and selection of the optimum connections type layout. The performance of these objective functions was investigated in optimal design of a three-story eccentrically braced frame, using two meta-heuristic algorithms: Enhanced Colliding Bodies Optimization (ECBO) and Enhanced Vibrating Particles System (EVPS). Then, the reliability indices of the optimal designs for both objective functions were calculated for the story lateral drift limits using Monte-Carlo Simulation (MCS) method. Based on the reliability assessment results of the optimal designs and taking the three levels of safety into account, the final designs were selected and their specifications were compared.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.869-881
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• 2023

A genetic improvement program in Korea was implemented to improve the performance of Hanwoo cattle by generating livestock with genetically desirable economic characteristics. In particular, in response to external changes, such as the expansion of Free Trade Agreement (FTA), the livestock genetic improvement program has increased farm income by improving the productivity and quality of Hanwoo cattle. Using production cost data from Statistics Korea, the total input and output indices of Hanwoo feeding cattle from 2008 - 2021 were estimated and the growth and productivity changes were analyzed. The productivity change measures results were used to estimate the cumulative effects of the Hanwoo genetic improvement program on quality improvement, another purpose of the program, using a finite distributed lag model. The average annual increase in output (market weight) of Hanwoo was 0.9%. However, total input increased by 1.6%, resulting in a 0.6% decline in total factor productivity. In contrast, the Hanwoo genetic improvement program contributed significantly to the production of high quality beef, rather than contributing to improved productivity of the cattle. Hanwoo carcass weight, which is used as a performance indicator for the livestock genetic improvement program, has significantly improved and is projected to increase at a slower rate. The collective findings indicate the need for new performance indicators that can comprehensively indicate the performance of the genetic improvement of Hanwoo.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.119-128
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• 2016

In a performance-based design, the structural safety is estimated from pre-defined damage states and corresponding damage indices. Both damage states and damage indices are well defined for above-ground structures, but very limited studies have been performed on underground structures. In this study, we define the damage states and damage indices of a cut-and-cover box tunnel which is one of typical structures used in metro systems, under a seismic excitation from a series of inelastic frame analyses. Three damage states are defined in terms of the number of plastic hinges that develop within the structure. The damage index is defined as the ratio of the elastic moment to the yield moment. Through use of the proposed index, the inelastic behavior and failure mechanism of box tunnels can be simulated and predicted through elastic analysis. In addition, the damage indices are linked to free-field shear strains. Because the free-field shear strain can be easily calculated from a 1D site response analysis, the proposed method can be readily used in practice. Further studies are needed to determine the range of shear strains and associated uncertainties for various types of tunnels and site profiles. However, the inter-linked platform of damage state - damage index - shear wave velocity - shear strain provides a novel approach for estimating the inelastic response of tunnels, and can be widely used in practice for seismic designs.

• Structural Engineering and Mechanics
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• v.81 no.4
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• pp.429-441
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• 2022

A probabilistic assessment of the seismic-excited buildings with a multiple-tuned-mass-damper (MTMD) system is carried out in the presence of uncertainties of the structural model, MTMD system, and the stochastic model of the seismic excitations. A free search optimization procedure of the individual mass, stiffness and, damping parameters of the MTMD system based on the snap-drift cuckoo search (SDCS) optimization algorithm is proposed for the optimal design of the MTMD system. Considering a 10-story structure in three cases equipped with single tuned mass damper (STMS), 5-TMD and 10-TMD, sensitivity analyses are carried out using Sobol' indices based on the Monte Carlo simulation (MCS) method. Considering different seismic performance levels, the reliability analyses are done using MCS and kriging-based MCS methods. The results show the maximum structural responses are more affected by changes in the PGA and the stiffness coefficients of the structural floors and TMDs. The results indicate the kriging-based MCS method can estimate the accurate amount of failure probability by spending less time than the MCS. The results also show the MTMD gives a significant reduction in the structural failure probability. The effect of the MTMD on the reduction of the failure probability is remarkable in the performance levels of life safety and collapse prevention. The maximum drift of floors may be reduced for the nominal structural system by increasing the TMDs, however, the complexity of the MTMD model and increasing its corresponding uncertainty sources can be caused a slight increase in the failure probability of the structure.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.447-453
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• 2013

Since PSDs(Platform Screen Doors) are set up at many subway stations, their design related to safety has become gradually important. In particular, the interference check with a running railway vehicle is the most important of performance indices because the collision between PSDs and vehicles can be dangerous for passengers in the car and on platforms. When the train comes into a station with a curvature, the passenger car has a large translational and rotational motion and the displacement is enough for coming in contact with PSD. The performance is affected by many design parameters such as rail design parameters and vehicle velocity. This study proposes dynamic analysis models for railway vehicles and rails. Some parameters were also considered in the models to determine their influence on the performance.