• Journal of the Korea Society for Simulation
• /
• v.31 no.4
• /
• pp.11-22
• /
• 2022

Unlike a short-range, a long-range underwater acoustic communication(UWAC) uses low frequency signal and deep sound channel to minimize propagation loss. In this case, even though communication signals are modulated using a covert transmission technique such as spread spectrum, it is hard to conceal the existence of the signals. The unconcealed communication signal can be utilized as active sonar signal by enemy and presence of underwater vehicles may be exposed to the interceptor. Since it is very important to maintain stealthiness for underwater vehicles, the detection probability of friendly underwater vehicles should be considered when interceptor utilizes our long-range UWAC signal. In this paper, we modeled a long-range UWAC environment for analyzing the detection performance of underwater vehicles and proposed the region of interest(ROI) setup method and the measurement of detection performance. By computer simulations, we yielded parameters, analyzed the detection probability and the detection performance in ROI. The analysis results showed that the proposed detection performance analysis method for underwater vehicles could play an important role in the operation of long-range UWAC equipment.

• Korean Journal of Weed Science
• /
• v.14 no.3
• /
• pp.199-211
• /
• 1994

Butachlor applied pre-emergence at 3.6kg ai/ha inhibited the growth and developments of shoot of barnyardgrass under dry condition, whereas rice was unaffected. Growth of rice and barnyardgrass under water condition was severely inhibited by treatment of butachlor but that of transplanted rice was not affected. The inhibition rate was higher under water condition, in broadcast rice and direct seeded rice than under dry condition, drilled rice and transplanted rice, respectively. The major anatomical response of stem of barnyardgrass seedling to butachlor under dry condition were partial reduction in thickness and collapse of leaf sheath, while not in rice. Broadcast rice on soil under water condition appeared reduction and constriction of leaf primordia thickness, and barnyardgrass formed tubular-like leaves and showed inhibited elongation of apical meristem. On the other hand, transplanted rice did not show these responses.

• Korean Journal of Weed Science
• /
• v.14 no.2
• /
• pp.128-143
• /
• 1994

At 5 DAS/T, leaf primordia of rice stems that were grown under dry condition in transverse sections were strongly stained while those under water condition had many aerenchyma cells well developed. On the other hand, leaf primordia and large air spaces in stem of transplanted rice were well developed. Rice in leaf anatomy had small and fine epidermal cells, chlorophyllous mesophylls, and bulliform cells but had no chlorophyllous vascular bundle sheath cells, while barnyardgrass leaf had large, rough and irregularly arranged epidermal cells, chlorophyllous vascular bundle sheath cells, and non-bulliform cells but had no chlorophyllous mesophylls. Epidermal cells of transplanted rice, however, were well developed, differentiated and sclerified. Cross sections of rice root under dry condition showed cell contents, regularly arranged cells, non-intercellular spaces and non-aerenchyma while under water condition had well-developed intercellular spaces, aerenchyma cells, small and densely arranged epidermis, sclerified exodermis and sclerenchyma cells. But root anatomy of transplanted rice consisted of finely, regularly arranged epidermis, well-developed intercellular spaces and nucleous cells.

• 대한근관절건강학회:학술대회논문집
• /
• 1997.05a
• /
• pp.125-133
• /
• 1997

• Life and Agrochemicals
• /
• s.265
• /
• pp.30-33
• /
• 2011

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2002.05a
• /
• pp.83-83
• /
• 2002

• 프린팅코리아
• /
• v.12 no.11
• /
• pp.92-93
• /
• 2013

(주)와이피엘(대표이사 지덕근)이 다수의 신형 장비를 선보이며, 디지털인쇄 후가공 장비 글로벌 리더로서의 입지 굳히기에 나섰다.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2016.05a
• /
• pp.387-388
• /
• 2016

• Journal of Digital Convergence
• /
• v.15 no.11
• /
• pp.113-120
• /
• 2017

The purpose of this study is to analyze how the relative proportion of retention between real estate for business and investment real estate among the real estate held by corporations has been changed after and before the Financial Crisis as well as whether there has been any difference between KOSPI and KOSDAQ listed companies in terms of their share of the real estate. The increasing pattern of real estate owned by KOSDAQ were similar to the KOSPI companies except for investment properties during the Financial Crisis. The proportion of real estate owned by KOSPI had been lower than that of KOSDAQ companies in both investment and business real estate before the Financial Crisis. However, during the period of the Financial Crisis, the proportion of real estate for business held by KOSPI firms was higher than that of KOSDAQ firms. Furthermore, the portion of investment of real estate owned by KOSPI has remained higher than that of KOSDAQ after the Financial Crisis period and the recent period. Based on the results of this analysis, how the relevance of the change of portion between real estate for business and investment real estate affects management performance will be figured out in the future studies.

• Korean Chemical Engineering Research
• /
• v.49 no.5
• /
• pp.657-663
• /
• 2011

Structure directing agent(SDA) containing piperidine moiety such as piperidine(PI), 2-methylpiperidine (MPI), 2,6-dimethylpiperidine(DMPI) and 2,2,6,6,-tetramethylpiperidine(TMPI), respectively has been utilized to synthesize aluminophosphate zeolite using hydrothermal method. The gel composition was $1.0Al_2O_3:1.0P_2O_5:0.76SDA:45H_2O$ and the hydrothermal heating was performed in an oven at 443 K and for 7 days at static mode. The obtained zeolitic material contained a lamellar structure when PI was used as the SDA. With a progressive increase of the SDA size, various structures of aluminophosphate including AlPO-5 of AFI structure were obtained. The aluminophosphate of SAS structure was formed when the largest TMPI was utilized as the SDA, which was confirmed by the Rietveld refinement. The result of $^{27}Al$ and $^{31}P$ MAS NMR of the sample suggested that Al and P were incorporated into the framework of the aluminophosphate.