• Smart Structures and Systems
• /
• 제4권3호
• /
• pp.343-365
• /
• 2008

In this study, the frequency domain method which utilizes the evaluation of changes in the structural mode shape is adopted to identify regions which contain localized damages. Frequency response function (FRF) values corresponding to the modal frequency, analogous to the mode shape coefficients, are used since change in natural frequency of the system is usually insignificant for localized damage. This method requires only few sensors to obtain the dynamic response of the structure at specific locations to determine the FRF via fast-Fourier transform (FFT). Numerical examples of an aluminum plate, which includes damages of varying severity, locations and combinations of multiple locations, are presented to demonstrate the feasibility of the method. An experimental verification of the method is also done using an aluminum plate with two different degrees of damage, namely a half-through notch and a through notch. The inconsistency in attaining the FRF values for practical applications due to varying impact load may be overcome via statistical averaging, although large variations in the loading in terms of the contact duration should still be avoided. Nonetheless, this method needs special attention when the damages induce notable changes in the modal frequency, such as when the damages are of high severity or cover more extensive area or near the boundary where the support condition is modified. This is largely due to the significant decrease in the frequency term compared to the increase in the vibration amplitude. For practical reasons such as the use of limited number of sensors and to facilitate automation, extending the resolution of this method of identification may not be efficient. Hence, methods based on wave propagation can be employed as a complement on the isolated region to provide an accurate localization as well as to trace the geometry of the damage.

• 정신신체의학
• /
• 제13권1호
• /
• pp.41-48
• /
• 2005

연구목적 : 사회복지학과 학생의 정신과에 대한 인식과 태도를 조사하여, 향후 정신과와 정신과 환자에 대한 적절한 인식과 태도를 함양할 수 있는 기초자료로 이용하고자 한다. 방 법: 설문에 응답한 사회복지학과 학생 67명과 사회복지사 34명을 대상으로 하여 정신과에 대한 인식과 태도와 삶의 질에 관한 설문을 이용하였다. 결과: 정신과 영역의 장점 요인과 일어날 수 있는 남용과 사회적 비난 요인과 경력과 개인적 보상 요인에서 사회복지학과 학생에 비하여 사회복지사가 유의하게 긍정적이었으며, 정신과 의사의 기능과 역할 정의 요인에서는 여성이 남성에 비하여 유의하게 긍정적이었다. 삶의 질의 하위 요인 중에서 활력 요인과 정신과에 대한 인식과 태도의 하위 요인 중에서 일어날 수 있는 남용과 사회적 비난 요인에서 유의한 상관관계가 있었다. 결론: 정신과 환자를 직접 접촉한 경험이 정신과에 대한 인식과 태도를 유의하게 긍정적으로 바꿀 수 있을 것으로 사료된다.

• 한국멀티미디어학회논문지
• /
• 제12권1호
• /
• pp.31-40
• /
• 2009

콜센터는 회사와 고객들을 연결하는 주요 접속점이 되고 있다. 최근 계속해서 진보하는 통신 기술로 인해 콜센터의 수나 규모도 극적으로 성장하고 있다. 총 운영비의 많은 부분을 차지하는 인건비를 미루어 볼 때 효율적인 상담원 배치 계획은 콜센터의 경제적이고 성공적인 경영을 좌우한다. 그러므로 상담원의 수를 효과적으로 결정하는 것이 무엇보다 중요하다. 이러한 의미에서 콜센터 운영 및 관리는 큐잉 이론을 이용하는 수리적 최적화 문제로 모델링 할 수 있다. 본 논문에서는 대기 중 중도포기를 하는 두 종류의 고객을 가지며 두 대기 큐들의 용량이 유한인 N-설계 콜센터의 근사적 분석을 상태분할 방법을 이용해 다루기로 한다. 콜센터의 성능 측도에 대한 시스템 파라미터들의 영향을 알아보기 위해 수치계산 예를 보여준다.

• 한국조경학회지
• /
• 제26권2호
• /
• pp.1-14
• /
• 1998

The purpose of this study is to find out how the urban landscape of Korea, especially Seoul, changed during the last half century since 1945. The modernization of Korea, which had begun in 1960's after the chaotic period caused by Korean War, influenced the rapid growth of cities and the radical changes of its structures. But the Western-minded planning theories based on rationalism and positivism was directly applied in developing our traditional cities and consequently the modern urban landscape including urban pattern, architectural style, and commercial and residential landscape revealed disharmony, discrepancy and inconsistency in skylines, streetscape and so on. The findings are summarized as follows. 1. Because the urban structure and pattern changed in undesirable manner in terms of land use and traffic circulation, cities as a whole resulted in exclusive and heterogeneous landscape, and citizens lost their identity and felt alienated. 2. Because the architectural forms of important and monumental buildings which influenced the character of streetscape were not so successful in inventing contemporary Korean Style in true sense, we still have difficulty in creating the urban landscape of originality and legibility. 3. Because from the beginning of this era almost all highrise buildings were designed by modernism-oriented western architects, the commercial landscape of central cities did not evoke a sense of place, and after the introduction of postmodernism this tendency is ore striking even in everyday ordinary streetscape. 4. The newly formed residential landscape which was mainly composed of highly dense and highrise apartment, not only evolved very overwhelming and ugly visual impact but also exposed many social problems in living condition, neighboring and face-to-face contact. In conclusion, in ordr to define the 'Koreanness' of our urban landscape, we have to struggle to combine traditional architectural heritage and native townscape with Western shape, thought and theory, no matter how difficult it may be.

• 한국펄프종이공학회:학술대회논문집
• /
• 한국펄프종이공학회 2011년도 춘계학술발표회 논문집
• /
• pp.169-169
• /
• 2011

Xylans are polysaccharides present in large amounts in cell walls of land plants. However, during kraft cooking, a high portion of hemicelluloses including xylans are dissolved in the cooking liquor. In the current trend for a more effective utilization of biomass, attention has been paid to the exploitation of xylans as strength-enhancing additives for paper. It is believed that surface xylan adds flexibility to the cell wall/fiber surface, resulting in stronger fiber-fiber joints or greater contact area between the fibers. Accordingly, there is proposal for a new pulping process involving the extraction of xylan prior to pulping, followed by their re-adsorption on the unbleached pulp. A suitable bleaching process should be employed then, which ought to does not only improve the brightness of the pulp, but also remain the effect of the adsorption of xylan on pulp fibers. The objective of this research was to investigate the impact of hydrogen peroxide bleaching on the properties of unbleached hardwood kraft pulp pretreated with birchwood xylan by measuring optical properties (brightness, post color number, opacity) as well as physical properties (tensile index, tearing index, bulk) of handsheets made from the bleached pulp. In the meantime, the influence of process variables of peroxide bleaching including bleaching temperature, time, initial pH and $MgSO_4$ dosage were studied.

• 수산경영론집
• /
• 제42권1호
• /
• pp.1-18
• /
• 2011

This paper analyze a description of Korean fleet using bottom gears on the high seas. The need for this study arises from international moves to address the effects of fishing with bottom gears on vulnerable marine ecosystems (VMEs) and in view of a communication on the Korean policy in respect of this. There is growing concern over the impact of fishing using gears that come into contact with the seabed (bottom gears), in particular in deep-sea areas where vulnerable marine ecosystems including seamounts, hydrothermal vents and cold water corals are located. Korea is an important stakeholder in high seas bottom gear fisheries. For the past eight years, the issue of protecting biodiversity in the deep-sea in areas beyond national jurisdiction has been extensively debated by the United Nations General Assembly (UNGA) and in other international fora. As a result of the report and a review by the UNGA of the effectiveness of the measures called for in resolution 59/25, the UN General Assembly called for a series of specific actions to be taken by States and RFMOs in UNGA resolutions 61/105 in 2006 and 64/72 in 2009 adopted by consensus. Korea attaches great importance to the protection of marine ecosystems and has made active efforts to implement the UNGA Resolution 61/105 in areas where there is a regional fisheries management organization, a process of establishing such organization or no such multilateral regime. For the effective implementation of the UNGA Resolution 61/105 and 64/72, Korea views that the development of support tools and, most importantly, the development of a global database on VMEs are urgently needed because many countries lack the ability to identify VMEs and to assess whether individual bottom fishing activities would have significant adverse impacts on their own.

• 전기학회논문지
• /
• 제64권1호
• /
• pp.136-142
• /
• 2015

In the paper, a design method of knee and pelvis joint in the biped robot is proposed for shock absorption and gravity compensation. Similarly to the human's body, the knee joints of the biped robot support most body weight and get a shock from the landing motion of the foot on the floor. The torque of joint motor is also increased sharply to keep the balance of the robot. Knee and pelvis joints with the spring are designed to compensate the gravity force and reduce the contact shock of the robot. To verify the efficiency of the proposed design method, we develope a biped robot with the joint mechanism using springs. At first, we experiment with the developed robot on the static motions such as the bent-knee posture both without load and with load on the flat ground, and the balance posture on the incline plane. The current of knee joint is measured to analyze the impact force and energy consumption of the joint motors. Also, we observe the motor current of knee and pelvis joints for the walking motion of the biped robot. The current responses of joint motors show that the proposed method has an effect on shock reduction and gravity compensation, and improve the energy efficiency of walking motions for the biped robot.

• 대한치과기공학회지
• /
• 제32권4호
• /
• pp.403-415
• /
• 2010

Purpose: The purpose of this study was to examine the eyesight and life habits of college students in an attempt to provide some information on the protection of their eyesight. Methods: The subjects in this study were 311 students in the department of dental technology at a college of health, on whom a survey was conducted. A crosstabulation analysis was carried out to show the joint distribution of general characteristics and several variables involving the use of glasses or contact lenses and life habits. Results: 77.5% of the students currently wore glasses due to weak sight. 9.3% took an eye test on a regular basis, and 31.2% did that every six months. As for the length of the length of daily mean reading time, 55.3% spent one hour or less reading books. The most common distance between eyes and books during their reading(44.7%) was 21 to 25. Concerning a reading posture, the biggest group(54.3%) lay down or lay on their face while they read books. 45.0 % spent less than an hour watching TV per day on average, and 27.0% were on the computer for 30 minutes to less than an hour per day on average. The greatest group(63.0%) made use of basic indoor lighting when they were on the computer at night, and 62.1% saw eye doctors to take an eye test. In relation to how to protect eyesight, the biggest group(50.5%) spent less time being on the computer. Conclusion: As the eyesight of college students fails due to reading, TV, computer, and improper ways and posture of doing or using those things, every college definitely should provide education on eye health as one of general education courses.

• Journal of Mechanical Science and Technology
• /
• 제17권1호
• /
• pp.1-10
• /
• 2003

This paper summarizes the results of the fatigue test of four composite bridge decks in extreme temperatures (-30$^{\circ}C$ and 50$^{\circ}C$ ). The work was performed as part of a research program to evaluate and install multiple FRP bridge deck systems in Dayton, Ohio. A two-span continuous concrete deck was also built on three steel girders for the benchmark tests. Simulated wheel loads were applied simultaneously at two points by two servo-controlled hydraulic actuators specially designed and fabricated to perform under extreme temperatures. Each deck was initially subjected to one million wheel load cycles at low temperature and another one million cycles at high temperature. The results presented in this paper correspond to the fatigue response of each deck for four million load cycles at low temperature and another four million cycles at high temperature. Thus, the deck was subjected to a total of ten million cycles. Quasi-static load-deflection and load-strain responses were determined at predetermined fatigue cycle levels. Except for the progressive reduction in stiffness, no significant distress was observed in any of the composite deck prototypes during ten million load cycles. The effects of extreme temperatures and accumulated load cycles on the load-deflection and load-strain response of FRP composite and FRP-concrete hybrid bridge decks are discussed based on the experimental results.

• 척추신경추나의학회지
• /
• 제2권1호
• /
• pp.99-114
• /
• 2007

Objectives : The purpose of this study was to introduce the Chuna Manual Therapy (CMT) using Bong (a type of stick which is called 'bong') as a part of Oriental Medicine. Methods : We searched several traditional methods of CMT using Bong, either individual contact to specialist of CMT using Bong or referred to publications, and summarized briefly for introduction. Authors also made a comparative study between existing CMT and CMT using the bong. Results & Conclusions : The indications of Bong CMT are regarded as acute or chronic pain syndrome, whiplash associated disorders, facet syndrome, vertebral misalignment, chronic fatigue syndrome, obesity and also lower extremity length difference caused by malalignment of vertebrae and pelvic bone. The Meridian Muscle Therapy by pressing down using the Bong can be carried out on the imbalances of the muscle by shortening and lengthening contraction. CMT with Bong is considered more effective than other existing CMT in terms of effectiveness. In the case of pelvic correction which needs a tremendous amount of force, it can reduce the force required effectively. This fact can be inferred by the theory of composition and decomposition of force during the transmission of power. We can perform Bong CMT feeling less fatigued subsequently than general CMT. Pressing down with flexed fingers to grip bong acts on the contraction of flexor digiti and extensor digiti muscle, this protects the $doctor^{\circ}{\emptyset}s$ wrist joints from injury. The bong which acts as a tool between the doctor and the patient, while being given treatment, absorbs and spreads out the direct impact from the patient to the doctor. CMT with Bong is able to apply to both existing massage therapies with the hand. The bong appliance can be used in all applications, particularly, but not limited to; Orthopedic and Manual Correction Therapy, Meridian Muscle Pressing, Exercise Therapy, and Meridian Point Manual Pressing Therapy. CMT with Bong belongs to the category of oriental rehabilitation and Chuna manual medicine.