• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.171-180
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• 2007

Reliability analysis of prestressed steel and concrete(PSSC) girders is conducted for deflection, stress and moment strength limit state. PSSC girder has strong advantages in terms of construction cost and vertical clearance for the span length of over 40 meters. In this paper, example PSSC girders with different span lengths, section dimensions and design stress levels are designed and analyzed to calculate the midspan deflection, stress and the section moment strength. Deflection limit state, stress limit state and strength limit state functions are assumed and the reliability indexes are obtained by Monte-Carlo simulation and Rackwitz-Fiessler procedure. The results show that the reliability of PSSC girder for deflection limit state is appropriately higher than the stress limit state and the reliability for moment strength is significantly conservative.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.283-292
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• 2005

This paper predicts premature failure load of reinforced concrete beams by epoxy-boned partially steel plates. A parametric study is conducted to estimate premature failure load of beams such as with or without stirrups, unplated length ratio, steel and reinforcement ratio, shear span to depth ratio of reinforcement beam. By results of finite element analysis, it turned out that the unplated length played a dominant role in partially plated beams but reinforcement ratio and shear span to depth ratio effected the premature failure load. The approximate expression with regard to combined design variables is compared with experimental results. It shows closely agreement.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.325-334
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• 2008

The standard prestressed concrete I-girder bridge (PSC I-girder bridge) is one of the most prevalent types for small and medium bridges in Korea. When determining the member forces in a section to assess the safety of girder in this type of bridge, the general practice is to use the simplified practical equations or the live load distribution factors proposed in design standards rather than the precise analysis through the finite element method or so. Meanwhile, the live load distribution factors currently used in Korean design practice are just a reflection of overseas research results or design standards without alterations. Therefore, it is necessary to develop an equation of the live load distribution factors fit for the design conditions of Korea, considering the standardized section of standard PSC I-girder bridges and the design strength of concrete. In this study, to develop an equation of the live load distribution factors, a parametric analysis and sensitivity analysis were carried out on the parameters such as width of bridge, span length, girder spacing, width of traffic lane, etc. As a result, the major variables to determine the size of distribution factors were girder spacing, overhang length and span length in case of external girders. For internal adjacent girders, the determinant factors were girder spacing, overhang length, span length and width of bridge. For internal girders, the factors were girder spacing, width of bridge and span length. Then, an equation of live load distribution factors was developed through the multiple linear regression analysis on the results of parametric analysis. When the actual practice engineers design a bridge with the equation of live load distribution factors developed here, they will determine the design of member forces ensuring the appropriate safety rate more easily. Moreover, in the preliminary design, this model is expected to save much time for the repetitive design to improve the structural efficiency of PSC I-girder bridges.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.83-91
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• 1988

This study was carried out to know the ecological study of the Pinus thunbergii stands on the southern seacoast of Korea. The results obtained were summarized as follows ; Density, mean acreage and mean distance of upper story of Pinus thunbergii were not difference by stands in the districts. Importance value of Pious thunbergii was 14 to 98% at the lower crown story in the eastern part of southern seacoast, and was 3 to 7% at the lower crown story in the western part of southern seacoast. The number of floristic composition was 26 species in the eastern part of southern seacoast, and was 37 species in the western part of southern seacoast. The species diversity index (H'), the maximum of species diversity (H' max.)and the evenness (J') in the western part of southern seacoast were shown higher than those in the eastern part of southern seacoast. Similarity index(SI) were highly shown among stands in the western part of southern seacoast, but were lowerly shown among stands in the eastern part of southern seacoast, and then were comparatively low in the western part of southern seacoast and the eastern part of southern seacoast.

• Korean Journal of Environment and Ecology
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• v.23 no.6
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• pp.553-563
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• 2009

This study was conducted to analyze the changes in the echolocation of Pipistrellus abramus according to environmental characteristics. The survey was conducted in the day-roosting site of P. abramus located in Gyeongju City (North Gyeongsang Province) from April to August, 2009. The environmental characteristics during the research were classified in six categories: the emergence time after sunset moving time from day roost to feeding areas; rice fields; forest edges; open spaces; and residential areas. Analysis results showed that there are differences in environmental characteristics and also differences between the moving time to the habitat and the moving time to capture preys. At the emergence time from day roost, Pipistrellus abramus used a FM signal with a short pulse-duration. In open spaces, however, they used a CF signal with a long pulse-duration. In different environmental situations, they used both FM and CF signals, although the types of pulse which they used were different. Except pulse-duration, there were significant differences in pulse-interval, peak-frequency, starting-frequency and ending-frequency between the movement among habitats and the movement to capture preys. Except the emergence time from day-roost, they showed a narrow band FM signal and a long pulse-duration that are suitable to search for insects by sensing echoes of insects when they moved among their habitats. When they were out to capture their preys, they showed a broad band FM signal and a short pulse-duration which enabled them to widely search and accurately locate their preys.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.33-40
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• 1969

1. Physicochemical properties of sea water and soil of Korean tidal flats densely populated with species of Mactra veneriformis, Cyclina sinensis, Meretrix lusoria, and Tapes philippinarum, were investigated in order to find out the index of environmental factors in marine bivalve culture. 2. The turbidity varied with the change in concentrations of organic matter, silicate, and the exchangeable copper in sea water. All of these concentrations in Inchon, Kunsan, and Hansando were higher than those in Yusoo. In the 5 areas investigated the lowest were ditected at Kangnung. 3. The minerals and organic matter content in sea water dia not vary significantly among the different bivalve beds. And it was presumed that the soil texture was one of the most important environmental factors for the density of the bivalves in tidelands. 4. The soil texture index of the different bivalve beds was obtained as follow: 5. There were no significant differences of pH, the exchangeable calcium, and the exchangeable copper contents of bottom soils in the 4 different bivalve beds. As important factors in these areas, it seems that the amount of chemical properties might not affect the distribution of bivalve species. 6. Among the 4 beds the soil organic matter content was highest at the T. philippinarum bed and varied with the total nitrogen content. 7. Among the different bivalve beds, it was significant that the water holding capacity and available phosphorus content were highest at the M. veneriformis bed.

• Journal of Veterinary Clinics
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• v.32 no.3
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• pp.268-271
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• 2015

About 2-year old northern goshawk (Accipiter gentilis) which is designated as natural monument (#323-1) in Republic of Korea was rescued by a local farmer and presented with a 2-weeks history of pain, swelling, stiffness and limping. On physical examination, plantar pododermatitis and digit IV weakness were observed. Radiographic findings also showed bone lyses with soft tissue swelling in the foot. A definite diagnosis was made as stage III bumble foot after multidisciplinary approach of the patient. Bacterial culture was performed, and concurrently antibiotic susceptibility testing is determined using wound site exudates specimen. Bacterial isolates were identified as Staphylococcus aureus, known normal skin flora. Treatment was initiated with surgical incision and necrotized tissues removal. Lavage-drainage and ball bandage were applied with topical mupirocin ointment application. Doughnut shaped pad was attached on bottom of the ball bandage to reduce weight bearing. After three weeks of intensive care, the wound site completely healed but digit IV weakness remained permanently. The goshawk returned to nature after eight weeks after treatment.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.498-507
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• 2012

This paper presents the ERRI design diagrams of KTX and HEMU applicable to simply supported single span bridges, and analyzes the dynamic characteristics and design considerations of the bridges under KTX and HEMU using the diagrams. The design diagrams of KTX and HEMU are calculated for the bridges with 25m, 30m, 35m and 40m span lengths, which are widely used for simple bridge in Korea. From the design diagrams, the dynamic characteristics of the bridges with the selected span lengths are analyzed. In addition, the design consideration is discussed to satisfy the design requirement of acceleration. It is desirable for the bridge with 25m span length to avoid resonance both for KTX and HEMU. Since larger responses are expected for HEMU in the bridge with 30m span length, and for KTX in the bridge with 35m and 40m span length, the bridges should be planned to have enough mass satifying acceleration requirement at resonance, or to avoid the resonance.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.33-39
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• 2017

This study identified a candidate area and route for construction of a hub & spork system for coastal passenger ships. For this purpose, the characteristics of the hierarchy structure of other transportation and the operating system of coastal passenger ships were analyzed. Evaluation factors for selecting alternative areas and routes for the construction project were then extracted. Secondly, the relative importance of these evaluation factors for alternative routes were calculated using the Analytic Hierarchy Process (AHP) method. Finally, the importance of these evaluation items and quality of the alternative areas and routes were considered to select a primary candidate area and route. Therefore, four evaluation items such as the number of passenger-ship routes, the number of passengers, the number of cars, and the number of residences were extracted, and the Mokpo area was selected as the target area. In addition, four evaluation items such as he number of islanders, the number of local governments, geographical conditions and passenger ship operators were extracted, and the Yeonggwang route was selected as priority candidates for this construction project. Meanwhile, for the expansive implementation, step-by-step promotion is needed along with the expansion of terminal facilities, the securing of large ships, and the introduction of a semi-public system for coastal passenger ships.

• Computational Structural Engineering
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• v.5 no.1
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• pp.4-10
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• 1992

이 글에서는 교량하중모델의 개발에 대하여 기술하였다. 사하중, 적재하중 및 충격하중에 대한 확률론적 모형이 제시되었다. 적재하중의 경우 트럭 Data Base를 기초로 하여 일차선 교량 또는 단경간(지간 약 40m까지)에서는 한대의 트럭이, 2차선 교량의 경우는 완전상관된 두대의 평행트럭에 의해 결정되어진다. 대부분의 경우 현재의 AASHTO의 보분배계수는 안전측이 된다.(특히 보간격이 긴 경우) 충격하중계수는 노면 요척 및 교량과 트럭의 동적특성을 고려한 모의해석을 통하여 구해지는데 두대의 차량을 고려한 경우가 한대의 트럭을 고려할 경우보다 더 낮은 것으로 나타났다.