• Steel and Composite Structures
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• v.5 no.6
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• pp.485-513
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• 2005

This paper presents a state-of-the-art on the behaviour of steel joints under fire loading and some recent developments in this field, currently being carried out by the authors. Firstly, a review of the experimental research work on steel joints is presented, subdivided into isolated member tests, sub-structure tests and tests on complete building structures. Special emphasis is placed on the seventh Cardington test, carried out by the authors within a collaborative research project led by the Czech Technical University in Prague. Secondly, a brief review of various temperature distributions within a joint is presented, followed by a discussion of the behaviour of isolated joints at elevated temperature, focussing on failure modes and analytical procedures for predicting the moment-rotation behaviour of joints at elevated temperature. Finally, a description of the coupled behaviour of joints as part of complete structures is presented, describing previous work and investigations on real fire (including heating and cooling phases) currently being carried out by the authors.

• Korean Journal of Metals and Materials
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• v.56 no.11
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• pp.796-804
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• 2018

The Charpy impact toughness of the heat affected zone (HAZ) of electro gas welded 390 MPa yield strength grade steel, manufactured by a thermo mechanically controlled process, was investigated. The effects of added Nb on the toughness of the steel and the factors influencing scatter in toughness are discussed in the present work. It was observed that adding Nb to the steel led to the deterioration of HAZ toughness. The presence of soluble Nb in the HAZ increased its hardenability and resulted in a larger amount of low toughness bainitic microstructure. Microstructural observations in the notch root area revealed the significant role of different microstructures in the area. In the presence of a larger amount of bainitic microstructures, the HAZ exhibited a lower Charpy toughness with a larger scatter in toughness. A softened zone with a lower hardness than the base metal was formed in the HAZ. However, theoretical analysis revealed that the presence of the zone might not be a problem in a real welded joint because of the plastic restraint effect enforced by surrounding materials.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.4
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• pp.1-10
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• 2011

This study investigates the performance of composite (steel-concrete) frame structures through numerical experiments on individual connections. The innovative aspects of this research are in the use of connections between steel beams and concrete-filled tube (CFT)columns that utilize a combination of low-carbon steel and shape memory alloy (SMA) components. In these new connections, the intent is to utilize the recentering provided by super-elastic shape memory alloy tension bars to reduce building damage and residual drift after a major earthquake. The low-carbon steel components provide excellent energy dissipation. The analysis and design of these structures is complicated because the connections cannot be modeled as being simply pins or full fixity ones they are partial restraint (PR). A refined finite element (FE) model with sophisticated three dimensional (3D) solid elements was developed to conduct numerical experiments on PR-CFT joints to obtain the global behavior of the connection. Based on behavioral information obtained from these FE tests, simplified connection models were formulated by using joint elements with spring components. The behavior of entire frames under cyclic loads was conducted and compared with the monotonic behavior obtained from the 3D FE simulations. Good agreement was found between the simple and sophisticated models, verifying the robustness of the approach.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.233-238
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• 2014

In case of the slender mass concrete like attached wall, retaining wall and bridge tower, the low heat cement and the control joint are mainly used for thermal cracking control. However, even if these cracking control methods are considered, it is impossible to control thermal cracks perfectly, because the external restraint is largely in these mass concrete. Because these cracks occurring in slender mass concrete members almost penetrate concrete member, the special cracking control is demanded in these mass concretes. The vertical pipe cooling method improving existing pipe cooling method was developed for the active thermal cracking control of slender mass concrete, and applied at the field attached wall. In results, the maximum temperature dropped more than $10^{\circ}C$ by vertical pipe cooling method, and the cracks decreased about more than 50%.

• Journal of the Korean Orthopaedic Association
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• v.55 no.4
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• pp.281-293
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• 2020

An anterior cruciate ligament (ACL) reconstruction is one of the most frequent surgical procedures in the knee joint, but despite the better understanding of anatomy and biomechanics, surgical reconstruction procedures still fail to restore rotational stability in 7%-16% of patients. Hence, many studies have attempted to identify the factors for rotational laxity, including the anterolateral ligament (ALL), but still showed controversies. Descriptions of the ALL anatomy are also confused by overlapping nomenclature, but it is usually known as a distinctive fiber running in an anteroinferior and oblique direction from the lateral epicondyle of the femur to the proximal anterolateral tibia, between the fibular head and Gerdy's tubercle. The importance of the ALL as a secondary restraint in the knee has been emphasized for successful ACL reconstructions that can restore rotational stability, but there is still some controversy. Some studies reported that the ALL could be a restraint to the tibial rotation, but not to anterior tibial translation. On the other hand, some studies reported that the role of ALL in rotational stability would be limited as a secondary structure because it bears loads only beyond normal biomechanical motion. The diagnosis of an ALL injury can be performed by a physical examination, radiology examination, and magnetic resonance imaging, but it should be assessed using a multimodal approach. Recently, ALL was considered one of the anterolateral complex structures, as well as the Kaplan fiber in the iliotibial band. Many studies have introduced many indications and treatment options, but there is still some debate. The treatment methods are introduced mainly as ALL reconstructions or lateral extra-articular tenodesis, which can achieve additional benefit to the knee stability. Further studies will be needed on the indications and proper surgical methods of ALL treatment.

• Journal of Oral Medicine and Pain
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• v.26 no.3
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• pp.205-214
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• 2001

오늘날 스트레스라는 단어는 모든 현대인과 방송, 언론매체에서도 매일 거론되어질 정도로그 중요성이 대두되고 있다. 의학계에서도 스트레스를 단순한 심리적 문제로 국한시키지 않고 과도한 스트레스가 지속될 경우 신경계와 내분비계, 면역계의 변화를 초래해 인체의 항상성에 영향을 미쳐 질병을 일으킨다는 것을 인식하고 있으며 이에 대한 연구가 진행되고 있다. 이러한 질병의 발생과정에서 생체의 일부조직이 파괴됨으로써 기능과 형태변화가 초래될 때 apoptosis가 관여하고 있으며 이에 본 저자는 스트레스와 구강악안면영역에서 발생할 수 있는 질병과의 상관관계를 규명하기 위해 이종의 한냉 스트레스와 다소의 굴신을 허용한 중등도의 구속 스트레스를 부여한 후 측두하악관절 활막의 변화를 전자현미경관찰을 통해 밝혀내고자 한다. Sprague-Dawley계 웅성 백서(200-230 g/bw) 33마리를 구속스트레스부여군 (12마리), 한냉스트레스부여군 (12마리) 및 정상군 (3마리)으로 나누고 이들을 각각 구속장치에 구속한 후 1, 3, 5, 7일에 각각 희생시켰으며 측두하악관절 활막의 변화를 전자현미경으로 관찰하였다. 그 결과는 다음과 같다. 1. 중등도의 구속스트레스군에서 사립체는 부분적으로 농축된 소견을 보였으며 수와 크기에 있어 시간이 지남에 따라 점차 감소하는 소견을 보였다. 2. 중등도의 구속스트레스군에서 과립내형질망은 점점 확장되었으며 불규칙한 형태를 나타내었다. 3. 중등도의 구속스트레스군에서 물결모양의 핵막의 이중구조가 7일군에서 관찰되었다. 4. 한냉 스트레스군에서 사립체는 1일, 3일군에서 약간 부푼 형태를 가지고 그 수가 다소 감소되었으나 시간이 지남에 따라 5일, 7일군에서 건강한 모양으로 점차 증가되었다. 5. 한냉 스트레스군에서 과립내형질망은 1일, 3일군에서 불규칙하게 확장된 소견을 보였으나 5일, 7일군에서는 잘 발달된 형태로 핵 주위에서 다수 관찰되었다. 6. 한냉 스트레스군에서 핵은 전 기간에 걸쳐 큰 변화를 보이지 않았다. 이와 같은 결과를 토대로 측두하악관절 활막조직은 한냉 스트레스 및 중등도의 구속 스트레스에 대하여 중등도의 저항성을 가지고 있는 것으로 생각되며 생리적 적응한계를 넘는 과도하고 지속적인 스트레스에 의하여 활막조직이 apoptosis되어 측두하악관절에 병리적 변화를 초래할 가능성이 있다고 사료되어 이후 지속적인 연구가 요구된다.

• Journal of Veterinary Clinics
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• v.11 no.2
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• pp.529-537
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• 1994

Sector scanner which has a conical end is used to image through the intercostal space because heart is protected by the ribs. Cardiac data published all around the world were also obtained by sector scanner. Although scanners being used in every small animal practice and animal hospital at college in Korea include convex ape and linear type, linear type is not appropriate f3r cardiac scan because of a wide contact surface. The purpose of this study is to establish ultrasonographic images of normal cardiac structures by measuring shape, size of reflectable cardiac structure according to restraint position in scanning normal heart of the puppies with 6.5 MHz convex scanner(SonoAce 4500, Medison, Korea) used in our veterinary teaching hospital, Seoul national university. Seventeen male and female puppies considered having healthy hear by X-ray and clinical examination are used feom April to July 1994. Scanning point selection of probe head and the distinction of imaged cardiac structures were accomplished by necropsy and cardiac scanning performed through thoracotomy under general anesthesia. At 10 o'clock position of transducer(at an angle of 30$^{\circ}$ between imaginary line from elbow joint to 3rd sternum and probe head, 60$^{\circ}$ from body surface, 4th intercostal space of right thorax) with the marker of scanner toward the head of dogs right atrium, left atrium and left ventricle were observed in 2, 3, 4, 5 intercostal space(2cm from the sternum) of experimental dog positioned ventrodorsally under general anesthesia. Under these conditions, the numerical values of imaged diastolic hear are as follows : the distance from skin to apex(mean$\pm$S.D) 47.53$\pm$6.94mm, thickness of left ventricular wall 6.00$\pm$1.60mm, length of left ventricle 16.27$\pm$5.31mm, width of left ventricle 15,33$\pm$4.25mm, length of left atrium 12.33$\pm$3.82mm, width of left atrium 11. 33$\pm$3.94mm, length of right atrium 1.00$\pm$2.41mm, width of right atrium 11.21$\pm$2.76mm and the area of left ventricle 270.92$\pm$109.81mm$^2$, area of left atrium 98.00$\pm$41.08mm$^2$, area of right atrium 62.75$\pm$21.04mm$^2$.

• Strategy21
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• s.46
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• pp.89-122
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• 2020

The longing for submarine manufacture and the fear of her power had exited for a long time, but submarine that could submerge and attack was built from 20th century by science technology development. The question, 'Submarine can exercise her power in naval warfare?' had exited before World War I, but the effective value of submarine was shown in the procedure of a chain of naval warfare during World War I and World War II. Germany and the United States made the best use of submarines at that time. The submarines of these nations mounted fierce attack on the enemy's battleships and merchant ships and blocked the sea lanes for war material. These fierce attack on ships became impossible After World War II, and the major powers reduced and coordinated the defence budget, so they considered the role of submarine. However, submarine is still powerful weapon system because she can secretly navigate under the water, and one of the most important force in the navy. The aim of this thesis is analyzing submarine roles in each naval warfare and integrating maritime strategy and weapon system technology into her roles. First, the research about represent submarine roles like anti-surfaceship warfare, anti-submarine warfare, intelligence gathering, land attack, supporting special operation and mine landing warfare will be presented, then the major naval warfare where submarine participated(during ex-World War I, World War I, World War II, The Cold War Era and post Cold War) and the analyzing of submarine roles by time will be presented. Submarine was developed for anti-surfaceship warfare during ex-World War I but could not make remarkable military gain in naval warfare because her performance and weapon was inadequate. However, the effective value of submarine in the procedure of a chain of naval warfare was shown during World War I and World War II. The major powers put battleships into naval warfare undiscriminatingly to command the sea power and submarines did massive damage to enemy navy power, so put a restraint the maritime power of enemy, and blocked the sea lanes for war material. After World War II, the battlefield situation changed rapidly and the concept of preemption became difficult to apply in naval warfare. Therefore, the submarine was unable to concentrate on anti-surfaceship mission. Especially during the Cold War era, nuclear submarine came to appear and her weapon system developed rapidly. These development gave submarines special missions: anti-submarine warfare and intelligence gathering. At that time, United States and Soviet submarines tracked other nation's submarines loaded with nuclear weapons and departing from naval their base. The submarines also collected information on the volume of ships and a coastal missile launching site in company with this mission. After Cold War, the major powers despatched forces to major troubled regions to maintain world peace, their submarines approached the shores of these regions and attacked key enemy installations with cruise missiles. At that time, the United States eased the concept of preemption and made the concept of Bush doctrine because of possible 911 terrorism. The missiles fired from submarines and surface battleships accurately attacked key enemy installations. Many nations be strategically successful depending on what kind of mission a submarine is assigned. The patterns of future naval warfare that my country will provide against will be military power projection and coalition/joint operations. These suggest much more about what future missions we should assign to submarines.