• Ocean Systems Engineering
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• 제2권2호
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• pp.115-135
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• 2012

The very low natural frequencies of tension leg platforms (TLP's) have raised the concern about the significance of the action of hydrodynamic wave forces on the response of such platforms. In this paper, a numerical study using modified Morison equation was carried out in the time domain to investigate the influence of nonlinearities due to hydrodynamic forces and the coupling effect between surge, sway, heave, roll, pitch and yaw degrees of freedom on the dynamic behavior of TLP's. The stiffness of the TLP was derived from a combination of hydrostatic restoring forces and restoring forces due to cables and the nonlinear equations of motion were solved utilizing Newmark's beta integration scheme. The effect of wave characteristics such as wave period and wave height on the response of TLP's was evaluated. Only uni-directional waves in the surge direction was considered in the analysis. It was found that coupling between various degrees of freedom has insignificant effect on the displacement responses. Moreover, for short wave periods (i.e., less than 10 sec.), the surge response consisted of small amplitude oscillations about a displaced position that is significantly dependent on the wave height; whereas for longer wave periods, the surge response showed high amplitude oscillations about its original position. Also, for short wave periods, a higher mode contribution to the pitch response accompanied by period doubling appeared to take place. For long wave periods, (12.5 and 15 sec.), this higher mode contribution vanished after very few cycles.

• 대한원격탐사학회지
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• 제19권4호
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• pp.277-284
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• 2003

이온층 구면을 사각형 격자로 분할하여 각 격자에서 총전자수를 추정하는 지역적 GPS 이 온층 모델을 제시한다. 한반도 상공을 위도와 경도 1$^{\circ}$$\times$1$^{\circ}$의 공간해상도를 가진 격자로 구분하고 칼만 필터(Kalman filter)를 이용하여 격자 상의 총전자수를 추정하였다. 이 연구를 위해 한국천문연구원에서 운영하고 있는 전국 규모의 9개 GPS 상시 관측소의 데이터를 이용하였다. 수신된 의사거리 데이터의 측정 잡음을 줄이기 위해 의사거리와 반송파 위상 데이터를 선형 조합한 위상보정 의사거리(phase-leveled pseudorange) 데이터를 새롭게 만들어 사용하였다. 또한 지역적 이온층의 변화에 적합한 태양-지자기 좌표계(solar-geomagnetic reference frame)를 이용하였다. 태양 활동이 비교적 활발하지 않은 때의 경우, 이 연구의 모델은 이온층 활동이 활발한 낮 시간대의 총전자수가 대략 30-45 TECU 정도로 나타났다. 이 모델의 신뢰성을 평가하기 위해 한국천문연구원(Korea Astronomy Observatory, KAO)의 지역적 모델과 Center for Orbit Determination in Europe의 전 지구적 모델에 의한 총전자수를 동일 지역에 대해 비교했을 때 5일 동안 약 4-5 TECU 정도의 RMS 차이를 보였다.

• 대한음성학회지:말소리
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• 제50호
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• pp.139-150
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• 2004

A Phonetic Tied-Mixture (PTM) model has been proposed as a way of efficient decoding in large vocabulary continuous speech recognition systems (LVCSR). It has been reported that PTM model shows better performance in decoding than triphones by sharing a set of mixture components among states of the same topological location[5]. In this paper we propose a Phonetic Tied-Mixture Syllable (PTMS) model which extends PTM technique up to syllables. The proposed PTMS model shows 13% enhancement in decoding speed than PTM. In spite of difference in context dependent modeling (PTM : cross-word context dependent modeling, PTMS : word-internal left-phone dependent modeling), the proposed model shows just less than 1% degradation in word accuracy than PTM with the same beam width. With a different beam width, it shows better word accuracy than in PTM at the same or higher speed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.819-824
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• 2005

Anchor system is widely used in construction works to support retaining structures. The compression anchor is characterized by excellent mechanism of pullout resistance, as well as less probability of progressive failure than a tension anchor. This paper presents the mechanical characteristics of a newly developed compression anchor(JR-2000). Field tests were performed to investigate characteristics of the pullout resistance of compression anchor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.497-500
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• 2001

Shunt reactors are used to compensate for capacitive VARs generated by lightly loaded transmission lines or underground cables. They are normally connected to the transformer tertiary winding. Dry-type shunt reactors have the advantage compared with oil-immersed shunt reactor as followings. Lower investment and maintenance cost, No fire hazard and no environmental concerns, Simple insulation to ground, Response to transient overvoltage less severe, Linearity of inductance versus load current, Lower-acoustic noise, Easier transport and handling due to lower weight, No oil-collecting system must be provided since there is no oil that can leak into the ground.

• 한국측량학회지
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• 제26권4호
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• pp.397-405
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• 2008

한 지점의 위치에 대한 정확도는 위성의 위치와 몇 가지 요인으로 인하여 발생하는 신호의 지연 등에 주로 의존하게 된다. 이러한 지연의 효과가 3차원 위치 오차에 미치는 영향을 분석하기 위하여 GPS 오차를 포함하는 GPS 관측 파일(RINEX)을 시뮬레이션 하고, 시뮬레이션된 관측 파일을 기선 처리하여 그 효과를 분석하였다. Bernese ver5.0을 이용하여 전리층 지연, 대류권 모델, DOP, 랜덤 오차 등 과 같은 GPS 오차를 시뮬레이션에 적용하였다. 실험결과 기선이 짧다면 무전리층 조합으로 인하여 전리층 지연 효과를 제거할 수 있기 때문에 TEC에 의한 위치오차는 그리 크지는 않았다. 그러나 기선이 길어진다면 3차원 위치오차는 최대 10cm까지 나타났다. 싸이클 슬립은 싸이클 슬립이 증가함에 따라 점차적으로3차원 위치오차가 변화되기 보다는 싸이클 슬립이 60%를 넘었을 때 좌표에 미치는 영향이 커짐을 알 수 있다. 이는 시뮬레이션된 싸이클 슬립이 위성에 골고루 분배되었기 때문에 싸이클 슬립에 의한 영향은 크지 않았으나 60%를 넘을 경우 그 오차는 급격히 증가하였다. 또한 DOP이 3보다 작은 경우, 2시간 선별하여 계산된 3차원 위치오차는 $3{\sim}4cm$ 정도 향상되었다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.275-278
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• 2002

The recognition of the natural background radiation is important not only for radiological education but also for the promotion of people's scientific view about radiation. We made a "room" on the web showing natural background radiation as part of a VRM (Virtual Radiation Museum). The "room" shows the video images of the tracks of charged particles from natural background radiation, alpha and beta ray track from known sources using a Large Scale Diffusion Cloud Chamber. The purpose of this study is to make clear the origin of a kind of track (named A-track) which is thick and easy to recognize with the length less than several cm in the cloud chamber, and to make numerical explanation of its counting rate. The study was carried out using a Large Scale Diffusion Cloud Chamber (Phywe, Germany) installed in the Niigata Science Museum. The Model RNC (Pylon Electronics, Canada) was used as Rn-222 source. Ra-226 activity in RNC was 111.6 Bq calibrated with NIST protocol. Rn-222 gas was injected into the cloud chamber. Continuous video recording with use of Digital Handycam (SONY, Japan) was carried out for 360 min. after injection of Rn-222 gas. The number of alpha-ray track (alpha track) in the video images was analyzed. The growth and decay curve of the total activity of Rn-222 and its alpha emitting progeny were calculated and compared with the count of the alpha tracks. As a result the alpha tracks formed by Rn-222 injection resemble A-Tracks. The relationship between A-track in the cloud chamber and atmospheric Rn is discussed.

• 한국운동역학회지
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• 제19권2호
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• pp.287-296
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• 2009

본 연구는 숙련자 4명과 3년 이내의 골프전공 학생 4명을 대상으로 아이언 클럽(3, 4, 5, 6, 7, 8, 9) 간의 기초샷 정보와 체중이동 정보를 분석하기 위하여 RD-TEC사의 샷분석기와 체중판을 이용하여 분석하였다. 본 연구의 목적은 기존 연구에서 다루어지지 않았던 전체 아이언 클럽간의 샷분석의 차이와 체중이동의 변화를 고찰하는데 그 목적이 있다. 실험대상자(숙련자 4명과 비숙련자 4명) 모두 헤드스피드와 볼스피드에서 롱아이언과 숏아이언의 차이는 통계적으로 유의하게 나타났으나, 3, 4, 5번 아이언에서는 에서 통계적으로 유의한 차이가 나타나지 않았다. 숙련자는 비숙련자보다 헤드스피드, 볼스피드, 방항성, 타출각에서 높은 결과를 나타냈다. 그리고 체중이동의 분석에서는 백스윙 톱에서는 비숙련자가 더 많은 체중이동(65.36%)을 하였고, 숙련자는 임팩트시에서 70.21%정도의 체중이 왼발에 있었다. 숙련자 그룹은 체중이동을 통하여 보다 효과적으로 파워를 내는 것으로 나타났다.

• Animal Bioscience
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• 제35권4호
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• pp.587-595
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• 2022

Objective: The present study was conducted to evaluate the effects of dietary supplementation with Bifidobacterium animalis, Agave fructans, and symbiotic of both encapsulated on growth performance, feed efficiency, blood parameters, and immune status in broiler chickens, and to compare these with diets including antibiotic growth promoters and without additives. Methods: A comparative experimental study was carried out with 135 male Ross 308 broiler chickens. Each trial was divided into 5 equal groups. Control group (CON) received a standard diet without growth promoter; GPA, a standard diet with colistin sulfate and zinc bacitracin (0.25 g/kg of feed); PRE, a standard diet with 1% Agave fructans; PRO, a standard diet with Bifidobacterium animalis (11.14±0.70 log CFU/g); SYM, a standard diet with B. animalis and Agave fructans. Results: A significant decrease in food consumption was found for the GPA, PRE, and SYM, compared to the CON group. The results show a better feed conversion index in PRE and GPA with respect to the CON group with the highest conversion index. Interestingly, the weight of the gastrointestinal tract shows a statistically significant difference between GPA and PRE groups. Moreover, the length of the gastrointestinal tract of the GPA group was less than the PRE group. In the total leukocyte count, there was a statistically significant increase in the GPA group compared to the CON, PRE, and PRO groups, and the heterophiles-lymphocytes index was lower in PRO. Regarding the cytokines, interleukin 10 (IL-10) decreased in PRO compared to CON and PRE, while IL-1β increased in the SYM group. Conclusion: Alternative treatments were shown to achieve similar productive results as growth-promoting antibiotics and showed improvement over diet without additives; however, they have immunomodulatory properties and improved the development of the gastrointestinal tract compared to the treatment of growth-promoting antibiotics.

• Archives of Plastic Surgery
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• 제32권4호
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• pp.491-495
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• 2005

In partial thickness burn injuries, silver sulfadiazine cream 1%(SSD, $Silvadene^{(R)}$) is the most commonly used topical agent worldwide. But silver sulfadiazine cream 1% has no exudate absorption property. Usually after escar is removed from wound surface, $Silvadene^{(R)}$ is changed to saline wet gauze dressing to promote epithelization. $Aquacel^{(R)}$(ConvaTec, UK) is a 100% sodium carboxymethylcellulose Hydrofiber material. It absorbs exudates directly into the hydrofibers by vertical wicking which allows rapid uptake of liquid into the fibers. The absorbed exudate fluid can be distributed to the entire dressing rather than just over the wound surface, which results in larger fluid absorption capacity. From April, 2003 to July, 2004 a study was done with 40 patients who had variable partial thickness burns. $Aquacel^{(R)}$ dressing was compared in 21 cases to silver sulfadiazine cream 1% and saline wet gauze dressings in 19 cases. In the $Aquacel^{(R)}$ cases, the average healing time on the face was $5.36{\pm}1.69$ a day; on the hands was $8.46{\pm}2.15$ a day; and, on the neck was $6.0{\pm}2.0$ a day. With the $Silvadene^{(R)}$ and Saline wet gauze dressing, the average healing time on the face was $6.44{\pm}1.74$ a day; on the hands was $13.79{\pm}5.35$ a day; and, on the neck was $11.17{\pm}3.31$ a day. As a result, the $Aquacel^{(R)}$ group showed a shorter healing time compared to the $Silvadene^{(R)}$ and saline wet gauze dressing group and patients were satisfied because of less pain and improved comfort. In conclusion, $Aquacel^{(R)}$ is a better choice for partial thickness burn injuries because of shorter healing time, less pain and more confortable dressing.