In this study, corrosion fatigue crack propagation was investigated in pH buffer environment using the giga strength steel and its heat-affected zone, and the results were compared with theoretical model prediction. Also, the pure corrosion effect on fatigue crack propagation in a corrosive environment was compared with the modified Forman equation. As results, the average value of corrosion rate obtained as the ratio of the net corrosion-induced crack length to the total crack length under cyclic loading in the base metal and heat-affected zone under experimental loading conditions. These results exhibit a new theoretical method for corrosion fatigue crack propagation that predicts a purely corrosion effect on the behavior to be determined.

Thick-walled pressure vessel has been autofrettaged in order to improve the fatigue life of the pressure vessel. The compressive tangential residual stress near the bore of the pressure vessel due the autofrettage process is benefical to the fatigue crack initiation and propagation of the pressure vessel. However, a reverse yielding due to the Bauschinger effect during the unloading process in autofrettage causes the reduction of the compressive residual stress near the bore. In order to evaluate the fatigue crack propagation life of the autofrettaged thick-walled pressure vessel, the Bauschinger effects were considered. Stress intensity factors of the crack at the inside surface of the pressure vessel due to operating pressure loading of 707 MPa and autofrettage loading with different levels of overstrain were calculated by using finite element methods, and used for evaluating fatigue crack propagation lives. Fatigue lives of the pressure vessel with the Bauschinger effects resulted in 45% to 67% reductions in fatigue life compared to those of the pressure vessel with ideal residual stress distributions depending on the autofrettage level.

This paper presents a dynamic crack propagation algorithm with Rayleigh damping effect based on the MLS(Moving Least Squares) Difference Method. Dynamic equilibrium equation and constitutive equation are derived by considering Rayliegh damping and governing equations are discretized by the MLS derivative approximation; the proportional damping, which has not been properly treated in the conventional strong formulations, was implemented in both the equilibrium equation and constitutive equation. Dynamic equilibrium equation including time relevant terms is integrated by the Central Difference Method and the discrete equations are simplified by lagging the velocity one step behind. A geometrical feature of crack is modeled by imposing the traction-free condition onto the nodes placed at crack surfaces and the effect of movement and addition of the nodes at every time step due to crack growth is appropriately reflected on the construction of total system. The robustness of the proposed numerical algorithm was proved by simulating single and multiple crack growth problems and the effect of proportional damping on the dynamic crack propagation analysis was effectively demonstrated.

The present study was performed reviewing references determine the infection status of Korean freshwater fishes and relation with climate change of Korean peninsula. The most common infections of Korean freshwater fishes are flatworms (trematodes) and spiny-headed worms (acanthocephalans). Total 61 species of Korean freshwater fishes for infectious disease has been reviewed. Among them, 44 species of freshwater fish belong to Cyprinidae and 17 species for Cobitidae, Siluridae, Bagridae, Amblycipitidae, Synbranchidae, Centropomidae, Odontobutidae, Belontiidae, and Channidae. The Korean freshwater fishes had total 35 kinds of parasite pathogenic organisms (Acanthocephala opsariichthydis, Centrocestus sp., Cyathocotyle sp., Diplostomum orientale, Diplostomum sp., Echinochasmus sp., Echinostoma sp., Genarchopsis sp., Holostephanus metorchis, Metacercaria hasegawai, Metagonimus sp., Metorchis taiwanensis, Neoplagioporus zacconis, Palliolisentis chinanensis, Palliolisentis chunjuensis, Prosorhpynchus sp., Centrocestus armatus, Clonorchis sinensis, Holostephanus nipponicus, Metorchis orientalis, Cyathocotyle orientalis, Pseudexorchis major, Exorchis oviformis, Trachelobdella sinensis, Metagonimus miyata, Isoparorchis hypselobagri, Clinostomum complanatum, Centrocestus asadai, Metagonimus yokogawai, Echinostoma cinetorchis, Echinochasmus japonicus, Diplozoon nipponicum, Metagonimus takahashii, Carassotrema koreanum, and Echinostoma hortense). Maximum infections belonged to Pseudorasbora parva as Cyprinidae had 19 kinds of parasite organisms, including Centrocestus armatus, Clinostomum complanatum, Clinostomum complanatum, Clonorchis sinensis, Cyathocotyle orientalis, Echinochasmus japonicus, Exorchis oviformis, Holostephanus metorchis, Holostephanus nipponicus, Metacercaria hasegawai, Metagonimus yokogawai, Metorchis orientalis, Metorchis taiwanensis, Pseudexorchis major, Cyathocotyle sp., Diplostomum sp., Echinochasmus sp., Metagonimus sp. and Prosorhpynchus sp. Human foodborne trematode infections are an important public health concern in Korea. In the future, under the climatic extremes on Korean peninsula such as floods, drought and temperature variability, in particular, the susceptibility of freshwater fishes to infection will be decreased.

To determine the status of Korean wild reptiles and amphibians infection and relation with climate change of Korean peninsula, references were reviewed. Wild animals serve as intermediate, reservoirs and paratenic hosts to zoonotic parasites of human beings. The parasites and disease can be a serious problem for all herptiles. The infectious diseases, in particular, become parasitized through contact with other reptiles or contaminated objects and environments, or by eating infected food items. Worms are one of the most common intestinal parasites. Among reptiles, the most common infections are flatworms (trematodes), roundworms (nematodes), tapeworms (cestodes), and spiny-headed worms (acanthocephalans). A total of 20 species for infectious diseases from Korean wild reptiles and amphibians has been reviewed. Among them, 11 species was amphibians and 9 species for reptiles. The Korean wild herptiles had total 41 kinds of parasite pathogenic organisms. Meximum infections belonged to Rana nigromaculata as amphibians had 22 kinds of parasite organisms, including Gorgodera aponica, Gorgodera bombinae, Diplodiscus japonicus, Haematoloechus sibiricus japonicus, Pleurogenoides japonicus, Haematoloechus nanchangensis, Haematoloechus variegatus, Haematoloechus lobatus koreanus, Neodiplostomum seoulense, Halipergus japonicus, Haematolechus japonicus, Loxogenes liberum, Baerttia japonica, Ophiotaenia manae, Oswardcruzia lualata, Icosiella kobayashi, Pharyngodon pobypedates, Gyrinicola japonica, Catadiseus sp., Ophisthodiseus sp., Diplorchis sp., and Sparganum. Also, Dinodon rufozonatum as reptiles had 5 kinds of parasite, including Cotylaspis coreensis, Cotylaspis sinensis, Cephalogonimus japonicus, Astiotrema reniferum, Astiotrema odheri, Kaurma orientalis, and Astiotrema sp.. In the future, under the climatic extremes on Korean peninsula such as floods, drought and temperature variability, in particular, the susceptibility of amphibian and reptiles to infection will be increased and they have implications for the emergence of disease and the potential for climate change to exacerbate amphibian decline.

본 연구에서는 산업의 혁신패턴이 기술체제에 좌우된다는 산업별 혁신체제론적 접근에 따라 산업의 기술체제 특성이 지식전파와 혁신성과에 미치는 영향을 분석하였다. 과학기술정책연구원의 「2008년 기술혁신활동조사: 제조업」DB 자료를 이용하여 기술체제에 따라 산업을 분류하고 계량모형을 이용해 지식외부성의 원천과 지식전파가 유발하는 기술혁신을 산업별로 분석하였는데, 주요결과는 다음과 같다. 첫째 특수적·암묵적 지식기반 산업에서는 일반적·명목적 지식기반 산업과 달리 기업의 혁신성과가 입지특성으로부터 영향을 받는 것으로 나타났으며, 고기술-특수적·암묵적 지식기반 산업에서는 연구개발자본이 풍부한 지역, 저기술-특수적·암묵적 지식기반 산업에서는 동종산업의 집적도가 높은 지역에 입지한 기업일수록 제품혁신이 활발하였다. 둘째 제품혁신을 선도적 혁신과 추종적 혁신으로 구분하여 지식전파가 유발하는 혁신수준을 산업별로 알아보았는데, 저기술산업에서는 외부로부터 전파된 지식이 선도적 혁신과 추종적 혁신을 유발하고 고기술산업에서는 추종적 혁신만 유발하는 것으로 나타났다. 이와 같은 분석결과로부터 지식외부성의 원천과 지식전파가 유발하는 기술혁신의 수준은 산업의 기술체제에 따라 다르며, 지역산업 클러스터정책은 산업의 기술체제 특성을 감안해 모색할 필요가 있다는 함의를 얻고 있다.

조직 구성원간의 신뢰는 조직내에서 지식을 창출하고 또한 창출된 지식이 조직내에서 전파되는 데에 지대한 영향을 미친다. 본 논문에서는 사회내의 기관, 제도등의 차이에 따라 조직내 구성원들간의 신념 공유나 상호 이해의 정도가 상이하며 이렇게 상이한 신념의 공유 정도나 상호 이해도가 조직내에서 지식을 창출하려는 동기부여나 창출된 지식의 조직내 전파 가능성 혹은 전파 범위나 속도 등에 영향을 미칠 수 있다는 것을 분석한 개념적 논문이다.

In this paper, the corrosion fatigue crack propagation behavior of structure rolled steel (SWS 41C) was investigated by changing the thickness, and this experiment was done by the three point bending corrosion fatigue tester. The main results obtained are as follows: 1) As the thickness of specimen becomes thicker, the corrosion sensitivity to initial stage crack becomes some sensitive, and that the fatigue life becomes more sensitive. 2) The crack growth rate to initial stage crack (da/dN) was retarded as the thickness of specimen becomes thicker. But after initial stage crack, as the thickness of specimen is more thicker, da/dN is more rapid. 3) As the corrosion fatigue crack length grows, the accelerative factor of thick specimen (t=12mm) is more higher than that of thin specimen (t=6mm). 4) As the corrosion fatigue crack length grows, the corroson potential of both thick specimen and thin specimen becomes more less noble potential, however thick specimen (t=12mm) tends to more less noble potential than that of thin specimen(t=6mm).

본 연구에서는 피로파괴에 영향을 주는 여러 인자중에서 우선 피로크랙전파에 대한 시험편 두께의 영향을 검토하기 위하여 최초 두께 25mm인 일반구조용 압연강재를 평면가공하여 두께 5, 10, 15, 20, 25mm인 CT 시험편을 가공한 후 인장-인장편진반 복피로시험을 행하여 실험한 결과 다음과 같은 결론을 얻었다. 1. 피로수명이 가장 짧게 나타나는 임의의 시험편 두께가 존재하며, 본 실험의 경우에는 두께 15m인 시험편의 경우 피로수명이 가장 짧게 나타났다. 2. 피로크랙의 발생은 두께가 두꺼운 시험편의 경우가 늦지만 피로크랙 성장은 두꺼운 시험편의 경우가 빠르게 나타났다. 3. 본 실험에서 paris시의 계수 m의 값은 절위는 1.98~4.59로서 시험편의 두께가 두꺼울수록 m의 값이 크게 된다.(이 논문의 결론부분임)