• Journal of Forest and Environmental Science
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• 제31권3호
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• pp.235-240
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• 2015

Zelkova serrata is an important hardwood species for the timber industry in Japan. Tree breeding programs for this species have mainly focused on growth characteristics such as stem diameter (D), tree height (TH), stem form, and branching. In order to fulfill timber industry needs, wood quality improvement should be included in the tree breeding program of this species. In the present study, growth characteristics, such as D and TH, and the stress-wave velocity (SWV), which is highly correlated with Young's modulus of wood, were measured for 20-year-old Z. serrata from eight half-sib families planted in a progeny test site with three different initial spacings. Significant differences in all the measured characteristics were found among the eight half-sib families. The variance components of the half-sib families for D, TH, and SWV were 27.2%, 47.3%, and 33.5%, respectively. These results indicate that all the measured characteristics of this species could be improved by tree breeding programs. In addition, only low correlation coefficients were obtained between the growth characteristics and SWV, indicating that extensive selection on SWV in tree breeding programs may not always lead to a reduction in yield volume.

• 원예과학기술지
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• 제16권2호
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• pp.242-243
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• 1998

상사화에 chipping, half-chipping, twin-scaling, coring, scooping 및 notching을 실시하여 번식능력과 1인1일구근처리량을 조사하여 가장 경제적인 인공번식법을 구명하고자 본 실험을 실시하였다. 번식능력의 경우 twin-scaling에 의해 1구당 42.19개의 가장 많은 자구를 얻었고 다음은 half-chipping (23.2개) > chipping(18.2개) > notching(14.3개) 순이었으며, coring과 scooping에 의해서는 평균 1개의 자구를 얻어 전혀 효과적인 인공번식법이 아님이 확인되었다. 이상의 결과에서 twin-scaling의 경우 일시에 많은 개체를 얻을 수 있었으나 하루에 200구 정도 작업이 가능하여 번식작업에 가장 많은 시간이 소요되었고 형성된 자구도 매우 작았다. 그러나 chipping의 경우는 하루에 480구 정도로 다른 인공번식법에 비해 가장 많은량을 작업할 수 있었고 또 자구도 비교적 큰 것을 얻을 수 있었으며, 유일하게 기계화가 가능하므로 가장 경제적인 인공번식법으로 판단되었다.

• 수산해양기술연구
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• 제46권2호
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• pp.173-183
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• 2010

In a split beam echo sounder, the transducer design needs to have minimal side lobes because the angular position and level of the side lobes establishes the usable signal level and phase angle limits for determining target strength. In order to suppress effectively the generation of unwanted side lobes in the directivity pattern of split beam transducer, the spacing and size of the transducer elements need to be controlled less than half of a wavelength. With this purpose, a 50 kHz tonpilz type transducer with a half-wavelength diameter in relation to the development of a split beam transducer was designed using the equivalent circuit model, and the underwater performance characteristics were measured and analyzed. From the in-air and in-water impedance responses, the measured value of the electro-acoustic conversion efficiency for the designed transducer was 51.6%. A maximum transmitting voltage response (TVR) value of 172.25dB re $1{\mu}Pa/V$ at 1m was achieved at 52.92kHz with a specially designed matching network and the quality factor was 10.3 with the transmitting bandwidth of 5.14kHz. A maximum receiving sensitivity (SRT) of -183.57dB re $1V/{\mu}Pa$ was measured at 51.45kHz and the receiving bandwidth at -3dB was 1.71kHz. These results suggest that the designed tonpilz type transducer can be effectively used in the development of a split beam transducer for a 50kHz fish sizing echo sounder.

• Journal of Radiation Protection and Research
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• 제44권2호
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• pp.72-78
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• 2019

Background: In the calibration and testing laboratory of Korea Atomic Energy Research Institute, the old X-ray generator used for the production of reference X-ray fields was replaced with a new one. For this newly installed X-ray irradiation system, beam alignment as well as the verification of beam qualities was conducted. Materials and Methods: The existing X-ray generator, Phillips MG325, was replaced with YXLON Y.TU 320-D03 in order to generate reference X-ray fields. Theoretical calculations and Monte Carlo simulations were used to determine initial filter thickness. Beam alignment was performed in three steps to deliver a homogeneous radiation dosage to the target at different distances. Finally, the half-value layers were measured for different X-ray fields to verify beam qualities by using an ion chamber. Results and Discussion: Beam alignment was performed in three steps, and collimators and other components were arranged to maintain the uniformity of the mean air kerma rate within ${\pm}2.5%$ at the effective beam diameter of 28 cm. The beam quality was verified by using half-value layer measurement methods specified by American National Standard Institute (ANSI) N13.11-2009 and International Organization for Standardization (ISO)-4037. For each of the nine beams than can be generated by the new X-ray irradiation system, air kerma rates for X-ray fields of different beam qualifies were measured. The results showed that each air kerma rate and homogeneity coefficient of the first and second half-value layers were within ${\pm}5%$ of the recommended values in the standard documents. Conclusion: The results showed that the new X-ray irradiation system provides beam qualities that are as high as moderate beam qualities offered by National Institute of Standards and Technology in ANSI N13.11-2009 and those for narrow-spectrum series of ISO-4037.

• 대한환경공학회지
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• 제30권12호
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• pp.1255-1261
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• 2008

생물활성탄(BAC) 재질별 EBCT 및 수온변화에 따른 HAA 5종의 생물분해 특성을 조사한 결과 다음과 같은 결론을 얻을 수 있었다. 본 연구에서 BAC에서 HAA 제거시 EBCT와 수온이 매우 큰 영향을 미치는 것으로 나타났다. EBCT와 수온을 증가시킬 경우 HAA의 제거율이 상승하였으며, 수온이 20$^{\circ}C$ 보다 높을 경우 HAA의 제거능은 EBCT의 영향을 크게 받지 않는 것으로 나타났다. 하지만 수온이 5$\sim$10$^{\circ}C$ 정도로 낮을 경우는 EBCT의 증가가 HAA의 제거율에 큰 영향을 미치는 것으로 나타났다. 활성탄 재질에 따른 BAC에서의 HAA 제거는 석탄계 재질에서의 생물분해능이 가장 높았고, 다음으로 야자계, 목탄계 순으로 조사되었다. HAA 5종에 대한 생물분해 속도상수와 반감기는 수온이 5$^{\circ}C$일 때의 HAA 5종에 대한 생물분해 속도상수(k)와 반감기(t$_{1/2}$)는 0.0373$\sim$0.1175 min$^{-1}$, 반감기는 5.9$\sim$18.58분이었으며, 수온을 10$^{\circ}C$와 20$^{\circ}C$로 증가시켰을 때 5$^{\circ}C$일 때와 반감기를 비교해 보면 1.5$\sim$7.9배로 감소되었다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.1035-1041
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• 2003

Recent studies among various activities taking place in order-picking warehouse system have shown various researches to reduce the order-picking costs occupying more than half the total costs. One way of improving the warehouse system performance is to separate from a picking area and a reserve area in one unit rack. This study is concerned on the performance evaluation model for picking and replenishing facility of refrigerated warehouse using simulation method. In this study, we developed a mathematical model to compute the system performance solve this problem using simulation method. We demonstrate the system performance using AutoMod Simulator and verify the results to compare mathematical results of the system performance of warehouse system. A systematic approach proposed n this study for an optimal planning of order-picking warehouse is known as an effective method for planning of order-picking warehouse and a performance evaluation problem considering both picking and replenishment.

• Transactions on Control, Automation and Systems Engineering
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• 제2권4호
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• pp.262-267
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• 2000

In this paper, the magnitude of undershoot and overshoot in a prototype second order system with one positive real zero is computed by the analytic methods. Also, it will be shown that the peak times of the undershoot and overshoot can be calculated using the impulse and step response of the second order system. Three different cases are investigated: underdamped(p<ζ<1), critically damped(ζ=1) and overdamped(ζ>1) cases. We deal with the undamped(ζ=0) case as a special case of the underdamped. And a compensation method is proposed to reduce undershoots of the nonmininmun phase system using feedforward compensator.

• Journal of Ship and Ocean Technology
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• 제6권1호
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• pp.34-53
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• 2002

Numerical solution of the forward-speed radiation problem for a half-immersed cylinder advancing in regular waves is presented by making use of the improved Green integral equation in the frequency domain. The B-spline higher order panel method is employed stance the potential and its derivative are unknown at the same time. The present numerical solution of the improved Green integral equation by the B-spline higher order Kelvin panel method is shown to be free of irregular frequencies which are present in the Green integral equation using the forward-speed Kelvin-type Green function.

• 한국안광학회지
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• 제8권2호
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• pp.111-117
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• 2003

국내외 썬글라스 반미러 코팅렌즈의 광학적 특성을 파악하기 위해, 분광광도계를 이용하여 반미러 코팅렌즈의 반사율을 측정하였으며, Macleod 프로그램을 이용해 계산한 결과와 비교 분석하였다. 또한 황금 색깔이 나는 TiN을 이용한 반미러 코팅렌즈를 설계하였고, 광학특성을 조사하였다. 반미러 코팅렌즈의 분석결과, 은색 투톤(two tone) 반미러 코팅은 금속 크롬(Cr)을 사용하였으며 경도를 증가시키기 위하여 크롬위에 $SiO_2$(또는 $Al_2O_3$)를 증착하여 사용하였다. 크롬 위에 증착되는 $SiO_2$의 두께는 10nm 정도가 적정한 것으로 판단된다. 칼라 반미러 코팅의 경우 디자인 결과는 각각 다음과 같다 ; blue 계열은 [air|$SiO_2$(66.3)|$TiO_2$(129.0)|$SiO_2$(62.9)|$SiO_2$(26.0)|$TiO_2$(120.3)|$SiO_2$(9.1)|glass]이며, gold 계열은 [air|$SiO_2$(60.6)|$TiO_2$(86.2)|$SiO_2$(13.5)|$TiO_2$(86.8)|$SiO_2$(214.38)|glass]이며, green 계열은 [air|$SiO_2$(74.3)|$TiO_2$(75.8)|$SiO_2$(44.3)|$TiO_2$(11.6)|$SiO_2$(160.8)|$TiO_2$(12.9)|$SiO_2$(183.3)|$TiO_2$(143.8)|glass]이며, silver 계열은 [air|$SiO_2$(21.2)|$TiO_2$(49.7)|$SiO_2$(149.3)|glass]이다. white 반미러 코팅인 경우는 [air|$SiO_2$(17nm)|$TiO_2$(43nm)(또는 $ZrO_2$)|$SiO_2$(87nm) polysiloxane($4.46{\mu}m$)|glass or CR-39]이며, 가시광선 영역(400~700 nm)에서 평균 19%의 반사율을 가지며 흡수가 적기 때문에 약 80%의 투과율을 보이는 white 타입의 반미러가 되게 된다. 황금빛 색깔을 띠는 반미러 코팅렌즈의 설계에 있어서 [air|$SiO_2$(170nm)|TiN(15nm)|glass]가 되면 CIE 좌표값은 거의 [air|Au(150nm)|glass]의 좌표값과 유사해지는 것을 볼 수 있었다.

• 한국잡초학회지
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• 제14권4호
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• pp.298-313
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• 1994

잔효기간이 긴 것으로 알려진 토양처리형 제초제 napropamide를 밭토양중 여러 환경조전하에 처리하여 이 약제의 토양중 분해성을 검토하고, 이 제초제가 토양미생물 상변화에 끼치는 영향에 대하여 실험을 실시한 결과는 다음과 같다. 살균토양과 비살균토양에서의 napropamide의 분해반감기는 각각 28.3, 14.6 일이었다. 수분함량의 차이에 따른 napropamide의 분해 속도는 60% > 80% ${\geq}$ 40% 순이였으며 napropamide의 처리와 무처리간의 미생물 발생수는 유의성이 없었고, 처리구내의 60% 수분함량구가 40% 수분함량구에서보다 세균수와 총균수가 많았다. pH의 차이에 따른 napropamide의 분해속도는 pH가 낮을수록 빨랐으며, napropamide처리구내 총균수는 pH5.5에서 경시적으로 증가하는 경향을 보였다. Napropamide의 분해속도는 $27^{\circ}C$ > $37^{\circ}C$ > $17^{\circ}C$의 순으로 빨랐으며, 각 온도에 있어서 napropamide 무처리구와 처리구간의 미생물수는 $17^{\circ}C$에선 방선균이, $27^{\circ}C$, $37^{\circ}C$에선 세균이 무처리구보다 처리구에서 증가됨을 알 수 있었다. Napropamide의 반감기는 10ppm과 20ppm처리에서 각각 16.6일과 21.1일이었고, 미생물 발생수는 20ppm처리구에서보다 10ppm처리구에서 많았다. 식양토와 미사질 양토에서 napropamide의 반감기는 27.7일, 17일이었으며, 처리구와 무처리구간의 미생물 발생수는 차이가 없었다. 포장 및 실내조건에서의 napropamide의 반감기는 각각 5.4일과 19.1일로 포장에서가 실내에서 보다 분해속도가 3.5배 빨랐다.