• Asian-Australasian Journal of Animal Sciences
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• 제26권10호
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• pp.1504-1510
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• 2013

Native chickens hold a significant share of the market in China. In response to the huge demand from the market, the productivity of Chinese native chickens needs to be improved. Cross breeding is an effective method to increase productivity, although it might affect meat quality. In this study, two pure lines (SD02 and SD03) of Erlang mountainous chickens were hybridized with a yellow feather and faster growing line (SD01). The effect of hybridization on carcass and meat quality (physiochemical and textural traits) was measured in the $F_1$ population at d 91 of age. The hybrids exhibited higher body weight and dressed weight, and amount of semi-eviscerated, eviscerated, breast muscle and abdominal fat (p<0.05). Abdominal fat yield also increased (p<0.05) compared to the offspring of the two pure-lines. Meanwhile, there was no significant difference in meat quality traits except for the myofiber diameter and density and the shear force of the breast muscle. Overall, the offspring of cross-lines were similar to pure lines in meat color, pH value, inosinic acid, crude protein, crude fat, dry matter, moisture content and amino acid composition in the breast muscle. These results suggest that productivity can be improved via cross-breeding while maintaining meat quality of the Erlang mountainous chicken.

• 한국구조물진단유지관리공학회 논문집
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• 제17권1호
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• pp.27-36
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• 2013

본 연구에서는 등대 구조물을 대상으로 한 면진기술 적용방안을 제시함으로써 지진에 대해 무방비상태에 놓여 있는 등대구조물의 지진안전도 확보방안을 제시하였다. 또한, 제안된 면진기술 적용방안을 활용하여 내진설계 이전에 지어진 등대를 대상으로 등대전체를 면진하였을 경우와 등대 렌즈만을 면진하였을 경우에 대하여 면진효과를 분석해 보았다. 해석결과, 등대 전체를 면진화하였을 경우 최대응답가속도와 층전단력 측면에서 충분한 면진효과를 얻은 반면, 등대 렌즈만을 면진화한 경우에는 렌즈부의 면진효과는 유효한 것으로 나타났으나 등대 자체의 안전이 확보되지 못한 상황에서는 등대의 파괴가 선행될 가능성이 있음에 주의할 필요가 있는 것으로 나타났다. 또한 등대전체와 렌즈를 동시에 면진화한 경우 비 면진구조 대비 유효한 면진효과는 나타내었지만, 최대응답가속도가 등대전체를 면진화한 경우보다 증가하는 경향을 나타내었으며, 렌즈의 면진화로 인한 층전단력의 감소가 미소함으로 이중면진의 적용으로 인한 실효성은 그 효과가 크지 않은 것으로 나타났다.

• Journal of Animal Science and Technology
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• 제60권9호
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• pp.22.1-22.7
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• 2018

Background: Cooking temperature and consequently doneness of beef muscles are most important for the palatability and consumer acceptability. Current study assessed the response of mechanical texture of Hanwoo muscles as a function of cooking temperature at different ageing days. Six muscles (Psoas major (PM), Longissimus thoracics (LT), Gluteus medius (GM), Semimembranosus (SM), Biceps femoris (BF) and Triceps brachii (TB)) were collected from each 10 Hanwoo steers. Warner-Bratzler WB-shear force (WBSF) and texture profile analysis (TPA) texture profiles were determined after 3 or 21 days of chiller, and randomly assigned to four groups; non-cooked, cooked at 55, 70 or $85^{\circ}C$. Results: Toughness of WBSF and TPA hardness of Hanwoo muscles were presence in the order of LT = PM = GM = SM < BF = TB (p < 0.001) for non-cooked raw muscle, and PM < LT = GM = SM < TB=BF (p < 0.001) for cooked meat aged for 3 days. WBSF linearly increased in 3 days aged meats after cooked at a higher temperature (P < 0.05). On the other hand, toughening of the muscles were significantly (P < 0.05) differed at various temperature when muscles were aged for 21 days. WBSF of PM and LT muscles were significantly increased at a higher cooking temperature, while other muscles (i.e., GM, SM, BF, TB) showed the lowest values at $70^{\circ}C$. In the case of TPA hardness, the effect of cooking temperature was very less in the toughness of the muscle (P > 0.05). Conclusion: Taken together, these findings clearly showed that the toughness of the muscle highly depends and varies upon the temperature and ageing of the muscle. Moreover, the effect of cooking temperature was very limited on aged muscles. The results mirror the importance of cooking temperature for objective measurements which ultimately estimate sensory tenderness and other quality traits.

• 한국축산식품학회지
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• 제32권5호
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• pp.598-603
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• 2012

Beef qualities which can be properly predicted by time-temperature integrator (TTI), a chromatic indicator, were selected in terms of its similarity of temperature dependence between beef qualities and TTI, denoted by Arrhenius activation energy ($E_a$). The high similarity is required to afford accurate prediction. A devised enzymatic TTI based on laccase (an oxidase), which catalyses the oxidation on 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) producing color development, was applied. The factors of beef quality, such as volatile basic nitrogen (VBN), pH, color (CIE $L^*$, $a^*$), Warner-Bratzler shear force (WBSF), Pseudomonas spp. count, and lactic acid bacteria (LAB) count were considered for the selection. $E_a$ (55.48 kJ/mol) of the TTI was found to be similar to those of the beef qualities (all referred) in the order of LAB count (53.54 kJ/mol), CIE $a^*$ value (61.86 kJ/mol), pH (65.51 kJ/mol), Pseudomonas spp. Count (44.54 kJ/mol), VBN (67.98 kJ/mol), WBSF (40.67 kJ/mol), and CIE $L^*$ value (33.72 kJ/mol). The beef qualities with more similar $E_a$ to that of the TTI showed less difference between real and TTI predicted levels. In conclusion, it was found out that when applying TTI to food packages, their $E_a$ similarity should be checked to assure accurate estimation of food quality levels from TTI response.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.5979-5986
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• 2013

본 연구에서는 복합재료 적층 쉘 구조의 기하학적 비선형 동적 거동을 상세 분석하였다. Sanders의 1차 전단 변형 쉘이론 및 비선형 방정식을 기반하여, 비선형 동적 방정식의 해는 Newmark 방법과 Newton-Raphson 반복법을 혼용하여 적용하여 산정하였다. 본 연구에서 개발한 유한요소 해석프로그램을 사용하여 쉘의 곡률, 화이버 보강각도 및 적층 배열의 변화가 적층 쉘의 기하학적 비선형 동적 거동에 미치는 영향을 상세 분석하였다. 몇 가지 수치해석 결과는 기존 문헌으로부터 얻어진 결과와 잘 일치하는 것으로 나타났다. 본 연구의 새로운 결과는 최대 동적변위에 대한 적층 쉘 구조의 곡률, 화이버 보강각도 그리고 적층 배열 형식과의 중요한 상호관계를 보여준다. 몇 가지 수치해석 예제는 동적 특성을 고려한 적층 쉘 구조를 상세 설계하는데 필요한 가이드라인을 제시할 수 있을 것으로 기대된다.

• Tribology and Lubricants
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• 제36권5호
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• pp.279-289
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• 2020

In this paper, a method is proposed for establishing an approximate prediction model of rotor-dynamics through modal testing. In particular, the proposed method is applicable to systems that cannot be established according to conventional methods owing to the absence of information regarding the dimensions and material of the rotor-bearing system. The proposed method is demonstrated by employing a motor dynamometer driven by a 1 MW class induction motor without dimension and material information. The proposed method comprises a total of seven steps, wherein an initial model is established by incorporating approximate dimensions and material information, and the model is improved on the basis of the natural frequency characteristics of the system. During model improvement, the modification factor is introduced for adjusting the elastic modulus and shear modulus of the system. Analysis of critical speed and imbalance response indicates that the separation margin is 67% and the maximum vibration amplitude is less than the amplitude limit of 0.032 mm under the API 611 standard, which means that the motor dynamometer can stably operate at a rated speed of 1800 rpm. Hence, the obtained results validate the feasibility of the proposed method. Furthermore, for broad usage, it is necessary to accordingly apply and validate the proposed method for various rotor-bearing systems.

• Steel and Composite Structures
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• 제34권4호
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• pp.499-509
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• 2020

The purpose of this paper is to investigate the degradation law of stiffness of steel-concrete composite beams after certain fatigue loads. First, six test beams with stud connectors were designed and fabricated for static and fatigue tests. The resultant failure modes under different fatigue loading cycles were compared. And an analysis was performed for the variations in the load-deflection curves, residual deflections and relative slips of the composite beams during fatigue loading. Then, the correlations among the stiffness degradation of each test beam, the residual deflection and relative slip growth during the fatigue test were investigated, in order to clarify the primary reasons for the stiffness degradation of the composite beams. Finally, based on the stiffness degradation function under fatigue loading, a calculation model for the residual stiffness of composite beams in response to fatigue loading cycles was established by parameter fitting. The results show that the stiffness of composite beams undergoes irreversible degradation under fatigue loading. And stiffness degradation is associated with the macrobehavior of material fatigue damage and shear connection degradation. In addition, the stiffness degradation of the composite beams exhibit S-shaped monotonic decreasing trends with fatigue cycles. The general agreement between the calculation model and experiment shows good applicability of the proposed model for specific beam size and fatigue load parameters. Moreover, the research results provide a method for establishing a stiffness degradation model for composite beams after fatigue loading.

• 수산해양기술연구
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• 제27권3호
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• pp.193-210
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• 1991

For the deckhouse or superstructure, attention is directed to the reduction of vibration from a human susceptibility point of view. The two basic requirements for obtaining a low vibration level in the accommodation are to ensure that excitation forces from propeller and/or main engine are small and to avoid resonance excitation of the hull and superstructure. In recent years increased attention has been directed towards the problems of vibration and noise in deckhouse, which have caused major problems with regard to the environmental quality in the living quarters for crews. Accordingly, in this paper, the characteristic of the vibration of deckhouse of fishing boat, of which the length/height ratio is also relatively high, are studied systematically with regard to the shape and modelling of deckhouse based on finite element method of 1-dimensional, 2-dimensional and 3-dimensional model. This study is divided into 4-part. 1st part is the global deckhouse vibration, 2nd part is the local deckhouse vibration, 3rd part consists of the estimation for stiffness of foundational support and 4th part is the application to TUNA LONG LINER of 416 ton class. For the global vibration analysis, the severity of the vibration depends on the longitudinal shear and bending stiffness of the deckhouse, on the vertical deckhouse support(fore, aft and sides). However, even if the design is technically sound, vibration problems may arise due to vertical or longitudinal hull girder or afterbody resonances. Author applied the method of this study to the analysis of, deep-sea fishing vessel of G.T. 416 ton class with relatively low height and long deckhouse, and investigated the vibrational characteristic of the fishing vessel with earlier structural feature. According to this investigation, the vibration, response of above vessel was confirmed of which main hull and deckhouse behave as one body. It is at the bottom of vibrational trouble which a accommodation part of the fishing vessel is raised, that is the local vibration for side wall, fore-aft wall and deck plate of deckhouse rather than thief fect of fore-aft vibration of deckhouse for above fishing vessel. and the resonance of main hull, deckhouse and driving system such as the main engine, propeller in exciting source is mainly brought up as the trouble.

• 한국구조물진단유지관리공학회 논문집
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• 제18권5호
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• pp.107-115
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• 2014

본 연구에서는 건물의 질량중심과 면진층의 강성중심 사이의 차이에 따른 면진효과에 대하여 살펴보았다. 면진기술은 면진층에 설치되는 면진장치의 성능에 크게 의존하는 기술이므로 면진장치 제작 후 전수검사를 통하여 면진장치의 수평강성을 검토하게 되어 있다. 하지만 면진장치 성능실험 시 각각의 면진장치의 품질기준은 건축기준에는 정해져 있지 않으며, 이로 인해 설계 시 적용된 강성과 실제 강성의 차이가 발생하여 면진층 상부 부재에 큰 문제를 야기할 수 있다. 연구결과, 최대응답변위의 차이는 크게 나타나지 않았으나 편심이 증가할수록 최대응답가속도, 층전단력 및 상부구조의 부재력은 크게 증가하여 일부 부재에서는 과도한 손상이 예상된다. 따라서 면진층은 실제 장치 제작 후 전수검사를 실시하여 반드시 설계된 의도대로 편심이 발생하지 않도록 장치를 재배치할 필요가 있으며, 가능하다면 건물의 질량중심과 강성중심의 차이는 동일하게 설계할 것을 추천한다.

• 한국지반공학회논문집
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• 제28권4호
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• pp.115-124
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• 2012

스톤칼럼으로 개량된 연약점토지반의 내진성능을 평가하기 위해 1g 진동대 실험을 수행하였다. 실험결과 스톤칼럼으로 보강된 모형지반의 거동은 지반과 스톤칼럼의 상호작용에 관한 Baez의 가정을 기초로 구성된 1차원 수치모델과 유사한 결과를 보였다. 실험결과와 수치해석 결과에 따르면 스톤칼럼으로 보강된 연약점토지반은 반복 연화현상(Cyclic softening)등으로 발생하는 과다한 전단변형이 감소하는 경향을 보이지만 단주기 특성을 가지는 지진파가 스톤칼럼으로 개량된 지반에 가해지는 경우에는 개량지반의 증가된 강성으로 인해 개량되지 않은 지반에 비해 가속도가 크게 증가하는 현상이 발생할 수도 있는 것으로 나타났다.