• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.2002-2009
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• 2006

This paper is primarily focused on the safe navigation between overtaking and overtaken vessels in restricted waterways under the external forces, such as wind and current. The maneuvering simulation between two ships was conducted to find an appropriate safe speed and distance, which is required to avoid collision. From the viewpoint of marine safety, a greater transverse distance between two ships is more needed for the smaller vessel. Regardless of external forces, the smaller vessel will get a greater effect of hydrodynamic forces than the bigger one. In the case of close navigation between ships under the forces of wind and current, the vessel moving at a lower speed is potentially hazardous because the rudder force of the lower speed vessel is not sufficient for steady-state course-keeping, compared to that of the higher speed vessel.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.1062-1065
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• 2002

We have evaluated the ability of a time-delayed artificial neural network (TDANN) to predict muscle forces using only eletromyographic(EMG) signals. To achieve this goal, tendon forces and EMG signals were measured simultaneously in the gastrocnemius muscle of a dog while walking on a motor-driven treadmill. Direct measurements of tendon forces were performed using an implantable force transducer and EMG signals were recorded using surface electrodes. Under dynamic conditions, the relationship between muscle force and EMG signal is nonlinear and time-dependent. Thus, we adopted EMG amplitude estimation with adaptive smoothing window length. This approach improved the prediction ability of muscle force in the TDANN training. The experimental results indicated that dynamic tendon forces from EMG signals could be predicted using the TDANN, in vivo.

• 한국전산구조공학회논문집
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• 제23권6호
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• pp.579-592
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• 2010

This paper presents a multi-phase model update approach for system identification of prestressed concrete (PSC) girders under various prestress forces. First, a multi-phase model update approach designed on the basis of eigenvalue sensitivity concept is newly proposed. Next, the proposed multi-phase approach is evaluated from controlled experiments on a lab-scale PSC girder for which forced vibration tests are performed for a series of prestress forces. On the PSC girder, a few natural frequencies and mode shapes are experimentally measured for the various prestress forces. The corresponding modal parameters are numerically calculated from a three-dimensional finite element (FE) model which is established for the target PSC girder. Eigenvalue sensitivities are analyzed for potential model-updating parameters of the FE model. Then, structural subsystems are identified phase-by-phase using the proposed model update procedure. Based on model update results, the relationship between prestress forces and model-updating parameters is analyzed to evaluate the influence of prestress forces on structural subsystems.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.89-93
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• 2006

This paper is primarily focused on the safe navigation between overtaking and overtaken vessels in restricted waterways under the external forces, such as wind and current. The maneuvering simulation between two ships was conducted to find an appropriate safe speed and distance, which is required to avoid collision. From the viewpoint of marine safety, a greater transverse distance between two ships is more needed for the smaller vessel. Regardless of external forces, the smaller vessel will get a greater effect of hydrodynamic forces than the bigger one. In the case of close navigation between ships under the forces of wind and current, the vessel moving at a lower speed is potentially hazardous because the rudder force of the lower speed vessel is not sufficient for steady-state course-keeping, compared to that of the higher speed vessel.

• 한국컴퓨터정보학회논문지
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• 제23권11호
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• pp.95-101
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• 2018

In this paper, we propose an efficient friendly forces location data sharing algorithm in a troops using a low bandwidth radio. The future battlefield is a 'Network Centric Warfare' with a concept of identifying the position and power of the enemy and friendly forces and leading the battlefield to victory through proper links at the time of our need. One of the basic elements in the 'Network Centric Warfare' is to share friendly forces location data. The bandwidth and transmission rates of radio used in battalion are low. Nevertheless, we should share our locations data almost in real time for effective fighting in a war situation. This paper describes the efficient method of friendly forces location data sharing based on low bandwidth radio. In particular, the concept of 'network-centered warfare' is reflected in the troop below the battalion to present an integrated and efficient way to shared location data of friendly forces.

• Strategy21
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• 통권32호
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• pp.5-35
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• 2013

The purpose of this thesis is to suggest how to plan ROK(Republic of Korea) Navy's strategy concerning to JOAC(Joint Operation Access Concept) and ASB(Air-Sea Battle) concept of US(United States) armed forces. Since 2006, US armed forces has been developing CONOPS(Concepts of Operations), JOAC & ASB. These concepts will not only affect security environment for Korea Peninsula and West Pacific Area, but also will be affected to ROK Navy's Strategy. Therefore, Korea Navy has to consider and review those concepts and should discuss the way to secure peace of Korea Peninsula. JOAC & ASB have been developed for securing operational access ability of US armed forces against enemy forces. A2/AD(Anti-Access, Area-Denial) is the strategy of possible enemy forces against US forces' approaching into the operation area and impede operations within area. US forces had to overcome enemy's A2/AD strategy in coming century to protect national interest and sustain global leadership. The main concept of JOAC & ASB is "Cross-domain Synergy", which means 'to eliminate duplicate and improve joint operability containing space and cyber operation area.' Korea Navy's acceptance of JOAC & ASB without any revising is not a rational choice. Without the amendment some problems can be occurred by the Korea navy's acceptance for the original version of JOAC & ASB. Those are "Missing differences of operation environment between Korea and US", "Impediment from neighbor nations, especially PRC (People's Republic of China)", and "Impediment inside from Korea armed forces". Therefore, Korea Navy has to evaluate and find out the way to solve for JOAC & ASB to apply for their strategy and minimise those possible problems above. This thesis is expected to be the solution.

• 한국해안해양공학회지
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• 제10권2호
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• pp.100-108
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• 1998

해양구조물의 연직 원형파일에 작용하는 파력은 파일 직경이 입사파장에 비해 매우 작은 경우에는 주로 항력과 관성력의 합으로 표시되는 Morison 식을 이용하여 결정하여 왔다. 그러나 Morison 식은 대칭형장을 유지하며 비교적 완만히 변화하는 파에 대해서 적용이 가능하다. 구조물 부재에 쇄파가 작용할 경우, 쇄파파력은 항력과 관성력에 추가하여 강한 충격쇄파력을 고려해야 한다. 본 연구는 임의 이차원 경사해빈에서 경계요소법을 적용하여 쇄파 내부점들의 수립자 속도 및 가속도를 계산하고, 이들을 이용하여 쇄파에 의한 쇄파파력을 계산하기 위한 모델기법을 수립하였다. 모델결과는 기존의 쇄파파력 측정 실험결과와 매우 잘 일치하였으며, Morison 식의 적용결과와 비교할 때 쇄파파력은 최고 약 3배, 모멘트는 최고 약 5배 정도 크게 나타났다

• 한국철도학회논문집
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• 제17권6호
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• pp.397-401
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• 2014

신개념의 해상 교통 인프라인 부유식 해중철도의 합리적인 설계를 위해서는 파랑 중에 해중철도 구조체에 가해지는 유체력을 추정하여야 한다. 간편하지만 정확도 높은 유체력 추정을 위해 유체동력학 이론을 이용한 계산식을 제안하고, 수조에서 상사 모형에 대해 실험을 수행하여 비교 평가하였다. Morison식과 선형 미소진폭 파이론을 이용하여 계산된 관성력과 항력은 모형 실험 결과를 통해 계측된 유체력과 양호한 일치를 얻었다. 해중철도 구조체에 작용하는 항력은 관성력에 비해 무시할 만한 수준이었고, 파력은 파수에 따라 큰 변동을 보이지 않으나 파고에는 선형적으로 비례함을 알 수 있었다. 선형 파이론과 Morison식은 해중철도 설계 시에 간편하고 유용하게 활용될 수 있음을 확인하였다.

• 동남아시아연구
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• 제24권2호
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• pp.127-165
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• 2014

This article regards the phase of political confrontations in Thailand and Burma as a prolonged and inconclusive political struggle between national revolution forces and civil revolution forces. It argues that in Thai case, anti-monarchy constitutional revolution has led to a right-wing national revolution based on state nationalism consolidating capitalist economic system by Sarit's military coup, while in Burmese case, anti-British imperialism movement in colonial era has resulted in a left-wing national revolution grounded on state nationalism associating with socialist economic system by Ne Win's military coup. It is also interesting to note that the two cases experienced state nationalism denying autonomous civil society as a process of nation-building in spite of their contrasting ideologies. In both cases, it became inevitable to have national revolution forces clinging to official nationalism and state nationalism confronting with civil revolution forces seeking popular nationalism and liberal nationalism. In particular, unlike Burmese society, Thai society, without colonial history has never experienced a civil war mobilizing anti-colonial popular nationalism including ethnic revolt. This article considers Dankwart Rustow's argument that national unity as a background condition must precede all the other phases of democratization, but that otherwise its timing is irrelevant. In this context, Thai democratization without national unity which began earlier than Burmese is taking a backward step. For the time being, there would be no solution map to overcome severe political polarization between the right-wing national revolution forces defending official nationalism cum state nationalism and the civil revolution forces trying to go beyond official nationalism towards popular nationalism cum liberal nationalism. In contrast, paradoxically belated Burmese democratization has just taken a big leap in escaping from serious and inconclusive nature of political struggle between the left-wing national revolution forces to defend official nationalism cum state nationalism and civil revolution based on popular nationalism cum liberal nationalism towards a reconciliation phase in order to seek solutions for internal conflicts. The two case studies imply that national unity is not a background condition, but a consequence of the process of political polarization and reconciliation between national revolution forces and civil revolution forces.

• Structural Engineering and Mechanics
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• 제63권3호
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• pp.347-359
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• 2017

Blast resistant gates are required to be lightweight and able to mitigate extreme loading effect. This may be achieved through innovative design of a gate and its supporting frame. The first is well covered in literature while the latter is often overlooked. The design of supporting frame depends mainly on the boundary conditions and corresponding reaction forces. The later states the novelty and the aim of this paper, namely, the analysis of reaction forces in supporting structure of rectangular steel gates subjected to "far-field explosions". Flat steel plate was used as simplified gate structure, since the focus was on reaction forces rather than behaviour of gate itself. The analyses include both static and dynamic cases using analytical and numerical methods to emphasize the difference between both approaches, and provide some practical hints for engineers. The comprehensive study of reaction forces presented here, cover four different boundary conditions and three length to width ratios. Moreover, the effect of explosive charge and stand-off distance on reaction forces was also covered. The analyses presented can be used for a future design of a possible "blast absorbing supporting frame" which will increase the absorbing properties of the gate. This in return, may lead to lighter and more operational blast resistant gates.