• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2245-2253
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• 2018

With the increase of electrical consumption and the unbalance of power demand and supply, power reserve rate is getting smaller and also the reliability of the power supply is getting deteriorated. Under this circumstance, the electrical energy storage (EES) System is considered as one of essential countermeasure for demand side management. This paper proposes efficient evaluation algorithms of multiple functions for EES systems, especially the secondary battery energy storage systems, in the case where they are interconnected with the power distribution systems. It is important to perform the economic evaluation for the new energy storage systems in a quantitative manner, because they are very costly right now. In this paper, the multiple functions of EES systems such as load levelling, effective utilization of power distribution systems and uninterruptible power supply are classified, and then the quantitative evaluation methods for their functions are proposed. From the case studies, it is verified that EES systems installed at distribution systems in a dispersed manner have multiple functions involved with direct and indirect benefits and also they can be expected to introduce to distribution systems with respects to economical point of view.

• 대한후두음성언어의학회지
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• 제19권2호
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• pp.89-95
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• 2008

주관적 음성평가는 음향분석기기를 이용한 객관적 음성 평가와 함께 음성분석에 유용하고 의미있는 평가방법이며 현재 알려진 검시법정 중에서 GRBAS 음성평가, VHI, patient self-perceptual voice rating이 가장 널리 사용되고 있고 인정받는 방법이다. 주관적 음성평가는 음성의 상태를 모두 대변할 수은 없으며 객관적인 음성평가에 대한 보완적인 의미를 가진다. 현재 개발되어 있는 주관적 음성평가 방법들이 유용한 평가도구이긴 하지만 나름대로의 문제점과 제한점을 가지고 있기 때문에 이에 대한 개선과 보완을 위한 지속적인 연구와 개발이 요구된다.

• 비파괴검사학회지
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• 제36권2호
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• pp.121-129
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• 2016

As the lifespan of concrete structures increases, their load carrying capacity decreases owing to cyclic loads and long-term effects such as creep and shrinkage. For these reasons, there is a necessity for stress state monitoring of concrete members. Particularly, it is necessary to evaluate the concrete structures for behavioral changes by using a technique that can overcome the measuring limitations of usual ultrasonic nondestructive evaluation methods. This paper proposes the use of a nonlinear ultrasonic method, namely, nonlinear resonant ultrasonic spectroscopy (NRUS) for the measurement of nonlinearity parameters for stress monitoring. An experiment compared the use of NRUS method and a linear ultrasonic method, namely, ultrasonic pulse velocity (UPV) to study the effects of continuously increasing loads and cyclic loads on the nonlinearity parameter. Both NRUS and UPV methods found a similar direct relationship between load level and that parameter. The NRUS method showed a higher sensitivity to micro-structural changes of concrete than UPV method. Thus, the experiment confirms the possibility of using the nonlinear ultrasonic method for stress state monitoring of concrete members.

• 한국콘텐츠학회논문지
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• 제13권5호
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• pp.117-125
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• 2013

인터랙티브 전자책에 대한 기존의 독자 이해도 평가 방법들은 대개 이해도 점수를 수치화하는 정량적 평가 방식들로, 개발자나 제작자가 그 의미를 구체적으로 해석하여 반영하기 어렵다. 본 논문에서는 인터랙티브 전자책의 상호작용성, 시각적 특성 및 내러티브 특성에 주목하여 독자의 스토리보드 재구성에 기반한 새로운 이해도 측정 방법을 제안하였다. 실제 독자의 읽기를 통한 이해도 질적 평가를 수행하였으며, 문제가 발생하는 구체적 내러티브 단계 및 상호작용 구성 적절성을 판별할 수 있는 정성적 평가 방법임을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.722-729
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• 2010

In this study, we considered the development for degree of compaction for intelligent compaction. In practice, any direct or indirect method can be used as a intelligent compaction method. A series of field tests was conducted using an accelerometer. This is quick and simple indirect methods of measuring soil stiffness. Each result was compared with the results from a plate load test. A prototype device for intelligent compaction was developed, and we evaluated its performance.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.57-61
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• 2001

In a main propulsion system of naval ship, DRME(Double Resilient Mounted Engine) is mostly adopted to ensure vibration isolation and shock resistance against underwater explosion weapon attack. In this paper, an analysis program for vibration and shock evaluation of DRME is presented. DRME is modelled as multi-rigid bodies with nonlinear mounts, and direct time integration method is introduced for shock analysis. The computed results are compared with those of foreign ones. Navy's proposed specifications are well satisfied with this program. This analysis program serves for the development of domestic DRME technology of naval ship.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1003-1005
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• 1997

To evaluate the quality of a system or its ability to perform a required function, it is necessary to quantify the reliability of that system. The reliability techniques are based on the concept of expected failure rate and average-outage-duration method. For each load point, the expected failure rate, average outage duration and average annual outage time are evaluated. This paper deals with the reliability evaluation for distribution system including the protection relay system. In evaluating the reliability, it suggests a method for the analysis of protective system reliability, that provides a probabilistic measure of the success of the protective apparatus to perform its intended function. The analysis shows the dependency of success on the reliability of many components, and the way this reliability may be enhanced by redundancy.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.423-427
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• 2004

In this work, we propose a new ultrasonic damage inspection method in plate structures. The proposed method employs an OPMT (Orientation-adjustable Patch-type Magnetostrictive Transducer) in order to make the ultrasonic waves focused on the specific target point. For experiments, virtual grid points were set up at every 50 mm in an aluminum plate and two OPMTs were used for inspection. If there exists a crack in a plate, the reflected Lamb wave from the crack is measured in addition to the direct waves from the transmitting transducer to the receiving transducer.

• Journal of the Korean Wood Science and Technology
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• 제43권4호
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• pp.486-493
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• 2015

설치된 데크재에 대한 성능을 평가하기 위하여 초음파 비파괴시험법을 사용하였다. 먼저 3종류의 데크재에 대해 트랜스듀서의 배치에 따른 직접법과 간접법간의 측정방법간의 차이를 검증하였으며 두 번째로 설치된 데크재의 사용시간의 경과에 따른 초음파속도를 측정 비교하였다. 마지막으로 데크재의 사용수명을 파악하기 위하여 사용시간의 경과에 따른 초음파속도의 변화를 조사하였다. 시험결과 직접법과 간접법간의 측정방법간의 차이는 없는 것으로 나타났으며 직접법에 대한 간접법의 비율은 1.02와 1.05로 각각 나타났다. 설치된 데크재에서 시간의 경과에 따라 초음파 속도는 감소하였으며 이들 간의 관계는 선형으로 나타났다. 시험결과로부터 초음파 비파괴시험법은 설치된 데크재의 유지보수에 관한 효율적인 수단이 될 수 있을 것으로 생각된다.

• Ocean Systems Engineering
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• 제7권4호
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• pp.399-412
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• 2017

The Gauss-Legendre integral method is applied to numerically evaluate the Green function and its derivatives in finite water depth. In this method, the singular point of the function in the traditional integral equation can be avoided. Moreover, based on the improved Gauss-Laguerre integral method proposed in the previous research, a new methodology is developed through the Gauss-Legendre integral. Using this new methodology, the Green function with the field and source points near the water surface can be obtained, which is less mentioned in the previous research. The accuracy and efficiency of this new method is investigated. The numerical results using a Gauss-Legendre integral method show good agreements with other numerical results of direct calculations and series form in the far field. Furthermore, the cases with the field and source points near the water surface are also considered. Considering the computational efficiency, the method using the Gauss-Legendre integral proposed in this paper could obtain the accurate numerical results of the Green function and its derivatives in finite water depth and can be adopted in the near field.