• 한국작물학회지
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• 제44권1호
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• pp.32-37
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• 1999

The experiment was conducted to investigate emergence response of lowland weeds at different soil moisture contents, burying depths and upon changes in soil moisture. Rice germination was over 50% at all burying depths under aerobic condition, but the emergence rate of the soil surface placed seeds in saturated and flooded conditions decreased by 19% and 29%, respectively, as compared with that of aerobic condition. Rice seeds at burying depth of over 3 cm did not emerge at all. The emergence rate of Echinochloa crus­galli (L.) Beauv. in aerobic condition was lower than 30%, but the emergence pattern of E. crus galli (L.) Beauv. at different soil moisture contents and seeding depths was similar to that of rice. Emergence behavior of lschaemum rugosum Salisb., Ludwigia octovalvis (Jacq.) Raven and Sphenoclea zeylanica Gaertn. which are dominant lowland weed species in the Philippines also differed depending on soil moisture conditions and burying depths. lschaemum rugosum Salisb. emerged at all burying depths under aerobic condition, whereasLudwigia octovalvis (Jacq.) Raven emerged only at 0 cm deep under saturated and aerobic condition and Sphenoclea zeylanica Gaertn. at 0 cm deep under flooding condition. Weed seeds planted at 1, 3, and 5 cm deep in continuous flooded and saturated condition did not emerge at all, but upon a change of soil moisture condition from saturated to drainage (S$\rightarrow$D) and flooded to drainage (F$\rightarrow$D), grass weeds began to germinate again and the average emergence rate in S$\rightarrow$D and F$\rightarrow$D were 26% and 5% forE. crus­galIi (L.) Beauv., 9% and 8% forI. rugosum SaIisb., respectively. Weed seeds buried in soil in the pot showed great emergence at S$\rightarrow$D but did not emerge under continuous flooded condition. The diversity index accounting for dominance degree and occurrence aspect of weed, was the lowest at F$\rightarrow$D.

• 전기학회논문지
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• 제61권2호
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• pp.329-334
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• 2012

The distribution submarine cables are normally used for power supply at island, which are mostly installed in the southern coast of KOREA, and partially installed in the west coast and Jeju-Island. There are two way of submarine cable burying system, buried and unburied type. Since 2003, KEPCO is entirely being constructing the distribution submarine cable by buried type. In this case, 'burial depth' is key index for evaluating the suitability of the buried situation. Therefore, the measurement accuracy of 'burial depth' is a big issue for burying system in the distribution submarine cable. This paper demonstrates the measurement error of burial depth that is affected by electrical factor such as grounding type of submarine cable in case of magnetic field detection method, and indicates the method to reduce the measurement error in buried type of distribution submarine cable system.

• 한국잡초학회지
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• 제32권3호
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• pp.180-187
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• 2012

Panicum maximum, Panicum repens, Imperata cylindrica, Pennisetum polystachion and Cyperus rotundus are five rhizomatous grass weeds that exist and are problematic in the coconut lands of Sri Lanka. Rhizomatous weeds are the most difficult to control because of their vegetative reproduction by underground propagules. Therefore chemical and biological techniques have failed to control these weeds to acceptable levels. Experiments were conducted to investigate the impact of depth of burial, duration of sun drying or duration of air drying rhizomes of the selected weed species on germination. Depth of burial reduced germination of all species. Burying rhizomes at depths less than 10 cm inhibited germination of P. maximum and P. polystachion. Burying depths below 30~40 cm inhibited germination of all species. Sun drying or air drying rhizomes for durations less than 5 days inhibited germination of P. maximum and P. polystachion. Germinations of all species were inhibited by sun drying rhizomes for 15 days or air drying rhizomes for 20 days. Sun drying of rhizomes of all species for five days reduced the moisture content to a greater extent than air drying. The results indicated that burying rhizomes at the depthsbelow 30~40 cm, sun drying rhizomes for durations beyond 15 days or air drying rhizomes for durations beyond 20 days would be effective in controlling germination of these species. The investigations of the experiments also suggest that keeping rhizomes on the soil surface without burying, sun drying rhizomes or air drying rhizomes for durations of 5~15 days would produce weak plants.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.754-757
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• 2009

The current concrete maturity method implemented with temperature sensors requires an extensive wiring, which is not often acceptable on construction site due to harsh working environment. Radio Frequency Identification (RFID) technology appears to provide a solution for the wiring issue because of its ability of sending data wirelessly. An RFID tag integrated with a temperature sensor and placed within fresh concrete may be able to read temperatures of concrete and transmit them to an RFID reader wirelessly in real-time. However the previous research illustrated that the RFID signal gets dispersed in liquid medium. One may speculate then whether RFID signals travel through fresh concrete with high water content. Would the tag's burying depth within fresh concrete affect its readability? The paper presents the preliminary results of our on-going investigation on the readability of RFID tags in concrete against water content and burying depth of tags.

• 생태와환경
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• 제56권4호
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• pp.375-383
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• 2023

모래잠입 어류는 모래 하상에 잠입하여 살아가는 생물로, 잠입을 통해 포식자 회피, 먹이 포획, 에너지 보존 등 생존에 이득이 있다. 국내에 서식하는 흰수마자는 전형적인 모래잠입 특성을 보임에도 불구하고 지속적인 개체군 감소로 인해 멸종위기종으로 지정되어있다. 본 연구에서는 흰수마자의 감소원인 파악을 위하여 모래크기 선호도 및 잠입 행동을 평가하였다. 전반적으로 1 mm 이하의 모래를 선호하는 것으로 확인되었으며, 유량에 따라 모래크기의 선택이 차이가 발생하였다. 또한 수온이 낮아짐에 따라 모래에 보다 깊이 잠입하였고, 잠입하는 깊이는 흰수마자의 크기별로 차이가 있는 것으로 나타났다. 흰수마자의 모래 선호도 연구 결과 전반적으로 개체군이 감소하는 원인은 댐, 보 등의 건설로 인한 물리적인 하상구조의 변화로 사료되었다. 특히, 구조물 건설 상류부의 정수역 형성으로 인한 실트와 진흙의 하상 내 축적과 하류부에 세립질 퇴적물 유입 감소 및 침식으로 인한 장갑화로 서식처 변형이 발생하여 잠입에 문제가 발생한 것으로 판단되었다. 흰수마자를 비롯한 모래잠입 어류는 모래 하상 구조가 생존 및 서식에 중요한 역할을 하기 때문에 이를 관리할 수 있는 효율적 전략 수립 및 서식지 관리가 필요하다.

• 한국해양공학회지
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• 제33권2호
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• pp.178-188
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• 2019

When burying underwater cables using robots, heading control is one of the key functions for the robots to improve task efficiency. This paper addresses the heading control issue for URI-T, an ROV for underwater construction tasks, including the burial and maintenance of cables or small diameter pipelines. Through modeling and identifying the heading motion of URI-T, the dynamic characteristics and input limitation are analyzed. Based on the identification results, a PD type controller with appropriate input treatment is designed for the heading control of URI-T. The performance of the heading controller was verified in water tank experiments. The field applicability of the proposed controller was also evaluated through the sea trial of URI-T at the East Sea, with a water depth of 500 m.

• 한국해양공학회지
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• 제33권3호
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• pp.300-311
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• 2019

An ROV trencher is a type of heavy-duty work class ROV equipped with high-pressure water jet tools for cutting into the sea floor and burying cables. This kind of trencher is mostly used for PLIB operations. This paper introduces the development of this kind of ROV trencher, which has a 698 kW power system, with a 250 kW hydraulic system and two 224 kW water jet systems. The project was launched in January 2014. After four years of design, manufacturing, and system integration, we carried out two sea trials near the Yeongilman port (about 20-30 m in depth) in Pohang to evaluate the system performance in November 2017 and August 2018. Through tests, we found that most of specifications were satisfied, including a maximum bury depth of 3 m, maximum bury speed of 2 km/h, and maximum forward speed of 1.54 m/s.

• Structural Monitoring and Maintenance
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• 제1권2호
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• pp.183-195
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• 2014

Scour is one of the leading causes of overwater bridge failures worldwide. While monitoring systems have already been implemented or are still being developed, they suffer from limitations such as high costs, inaccuracies, and low reliability, among others. Also, most sensors only measure scour depth at one location and near the pier. Thus, the objective is to design a simple, low cost, scour hole topography monitoring system that could better characterize the entire depth, shape, and size of bridge scour holes. The design is based on burying a robust, waterproofed, piezoelectric sensor strip in the streambed. When scour erodes sediments to expose the sensor, flowing water excites it to cause the generation of time-varying voltage signals. An algorithm then takes the time-domain data and maps it to the frequency-domain for identifying the sensor's resonant frequency, which is used for calculating the exposed sensor length or scour depth. Here, three different sets of tests were conducted to validate this new technique. First, a single sensor was tested in ambient air, and its exposed length was varied. Upon verifying the sensing concept, a waterproofed prototype was buried in soil and tested in a tank filled with water. Sensor performance was characterized as soil was manually eroded away, which simulated various scour depths. The results confirmed that sensor resonant frequencies decreased with increasing scour depths. Finally, a network of 11 sensors was configured to form a distributed monitoring system in the lab. Their exposed lengths were adjusted to simulate scour hole formation and evolution. Results showed promise that the proposed sensing system could be scaled up and used for bridge scour topography monitoring.

• 한국작물학회지
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• 제39권6호
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• pp.531-536
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• 1994

벼 무논골뿌림재배에 알맞는 파종 전 논 굳힘정도와 파종골깊이를 구명하기 위하여 1993년에 전 북통(미사질토양)에서 동진벼를 공시하고 논 굳힘 일수와 파종골깊이를 달리하여 시험한 결과를 요약하면 다음과 같다. 1. 입모율은 논 굳힘 일수가 길수록 골깊이가 얕을수록 높았으며, 원추 관입심은 논 굳힘일수가 길수록 낮아졌는데 무논골뿌림재배에 알맞는 굳힘 일수는 4일로 이때 토양의 경도는 원추 관입심으로 6∼7cm 정도이었다. 2. 줄기 매몰심도는 논 굳힘일수가 짧을수록, 골이 깊을수록 깊어졌는데 줄기 매몰정도가 낮았던 4일 또는 6일 굳히고 골깊이를 2cm로 한 처리에서는 도복이 발생하였다. 3. 출수기는 입모수가 적었던 골깊이 6cm처리에서 4cm처리보다 1∼2일이 지연되었다. 4. 쌀 수량은 2일 굳힘에서는 골깊이 2cm에서, 4일 굳힘에서는 골깊이 4cm에서, 6일 굳힘에서는 골깊이 6cm에서 가장 많았다. 5. 이상에서와 같이 미사질토양에서 벼 무논골뿌림 재배시 입모율, 도복, 및 수량을 고려한 파종 전 논 굳힘 일수는 4일로써 토양경도는 원추 관입심으로 6∼7cm이며 이때 파종골의 깊이는 4cm로 하는 것이 좋을 것으로 생각된다.

• Mycobiology
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• 제31권2호
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• pp.105-112
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• 2003

Sclerotia of Grifola umbellata were cultivated by two methods such as burying and root inoculation methods. The sclerotia of G. umbellata produced by the burying method were $6.0{\sim}6.8{\times}3.4{\sim}4.6{\times}1.8{\sim}1.9cm$(Width$\times$Length$\times$Thickness) in size and $17.3{\sim}19.6g$ in weight, respectively. Their increase rate was $1.10{\times}1.12$ times. On the other hand, the sclerotia cultivated by the root inoculation method were $18.3{\sim}31.5{\times}12.5{\sim}26.4{\times}3.1{\sim}3.7cm(W{\times}L{\times}T)$ in size and $219.1{\sim}576.6g$ in weight, respectively. Their growth increment was $11.18{\sim}39.77$ times. The rhizomorphs of Armillaria mellea were developed with a high density under fallen leaves layer covering cultivation site, and distributed mainly between soil surface and soil depth of about 10 cm as well as colonized prominently on the inoculated wood logs. Fungal interaction between G. umbellata and A. mellea were observed mainly in the stage of white sclerotium of G. umbellata. The sclerotia of G. umbellata which were developed newly and harvested in the root inoculation method were twined with root hairs of host tree and rhizomorphs of A. mellea. The sclerotia of G. umbellata decomposing root hairs of host tree were confirmed through SEM examination. Physiochemical characteristics of soil in all cultivation sites had no significant differences. Soil pH were in the range of pH $3.98{\sim}4.40$. Organic matters were the range of $17.97{\sim}23.86%$ and moisture contents of soil were $12.00{\sim}18.20%$. Soil temperatures showed $12.9{\sim}13.8^{\circ}C$ in November and $22.0{\sim}23.9^{\circ}C$ in August, respectively. In conclusion, the root inoculation method seems to be a practical method for cultivating sclerotia of G. umbellata due to its many advantages such as simplicity of inoculation process, shortening of cultivation periods and facility of harvest.