• Ecology and Resilient Infrastructure
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• v.10 no.3
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• pp.85-96
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• 2023

The study involved the categorization of domestic lakes located in South Korea into three groups based on their salinity levels: upstream reservoirs with salinity less than 0.3 psu, estuarine reservoirs with salinity ranging from 0.3 to 2 psu, and brackish lagoons with salinity exceeding 2 psu. Subsequently, the research assessed variations in the concentrations of total nitrogen (T-N) and total phosphorus (T-P) in the sediment of these lakes using statistical analysis, specifically one-way analysis of variance (ANOVA). Additionally, a laboratory core incubation test was conducted to investigate the benthic nutrient fluxes in Songji lagoon (salinity: 11.80 psu), Ganwol reservoir (salinity: 0.73 psu), and Janggun reservoir (salinity: 0.08 psu) under both aerobic and anoxic conditions. The findings revealed statistically significant differences in the concentrations of T-N and T-P among sediments in the lakes with varying salinity levels (p<0.05). Further post-hoc analysis confirmed significant distinctions in T-N between upstream reservoirs and estuarine reservoirs (p<0.001), as well as between upstream reservoirs and brackish lagoons (p<0.01). For T-P, a significant difference was observed between upstream reservoirs and brackish lagoons (p<0.01). Regarding benthic nutrient fluxes, Ganwol Lake exhibited the highest diffusive flux of NH₄⁺-N, primarily due to its physical characteristics and the inhibition of nitrification resulting from its relatively high salinity. The flux of NO₃^--N was lower at higher salinity levels under aerobic conditions but increased under anoxic conditions, attributed to the impact of salinity on nitrification and denitrification. Additionally, the flux of PO₄^3--P was highest in Songji Lake, followed by Ganwol Lake and Janggun Reservoir, indicating that salinity promotes the diffusive flux of phosphate through anion adsorption competition. It's important to consider the influence of salinity on microbial communities, growth rates, oxidation-reduction processes, and nutrient binding forms when studying benthic diffusive nutrient fluxes from lake sediments.

• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.919-928
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• 2023

Rainfall characteristics in Korea are concentrated during the summer flood season. In particular, when a large amount of turbid water flows into the dam due to the increasing trend of concentrated rainfall due to abnormal rainfall and abnormal weather conditions, prolonged turbid water phenomenon occurs due to the overturning phenomenon. Much research is being conducted on turbid water prediction to solve these problems. To predict turbid water, turbid water data from the upstream inflow is required, but spatial and temporal data resolution is currently insufficient. To improve temporal resolution, the development of the Turbidity-SS conversion equation is necessary, and to improve spatial resolution, multi-item water quality measurement instrument (YSI), Laser In-Situ Scattering and Transmissometry (LISST), and hyperspectral sensors are needed. Sensor-based measurement can improve the spatial resolution of turbid water by measuring line and surface unit data. In addition, in the case of LISST-200X, it is possible to collect data on particle size, etc., so it can be used in the Turbidity-SS conversion equation for fraction (Clay: Silt: Sand). In addition, among recent remote sensing methods, the spatial distribution of turbid water can be presented when using UAVs with higher spatial and temporal resolutions than other payloads and hyperspectral sensors with high spectral and radiometric resolutions. Therefore, in this study, the Turbidity-SS conversion equation was calculated according to the fraction through laboratory analysis using LISST-200X and YSI-EXO, and sensor-based field measurements including UAV (Matrice 600) and hyperspectral sensor (microHSI 410 SHARK) were used. Through this, the spatial distribution of turbidity and suspended sediment concentration, and the turbidity calculated using the Turbidity-SS conversion equation based on the measured suspended sediment concentration, was presented. Through this, we attempted to review the applicability of the Turbidity-SS conversion equation and understand the current status of turbid water occurrence.

• Korean Journal of Agricultural Science
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• v.29 no.2
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• pp.20-34
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• 2002

This study was conducted to examine the effects of an Aspergillus oryzae fermentation culture on the in vitro digestibilities of dry matter, crude fiber, acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein, and pH in in vitro experiment of diets for dairy cows. A fungal species, Aspergillus oryzae was supplied by Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea (KCTC 1229). The experimental diets were commercial compound feed (concentrate) and total mixed ration (TMR) for lactating cows, of which chemical analyses were determined at Research and Development Institute, Woosung Feed Co., Ltd., while the digestibilities were done at the laboratory of Chungnam National University. Aspergillus oryzae culture products were added to compound feed and TMR at the rate of 0, 1.0, 2.0, 3.0% respectively. The experimental diet with the rumen fluid sampled from Holstein fresian milking cows were used and digested for 24 hrs, 48hrs and 72hrs in the shaking incubator. The residues of the digesta were digested for 48hrs in the incubator in which put 30ml of 0.1N HCl with 0.2% pepsin at $39^{\circ}C$. The final precipitates were dried for 48hrs in the drier at $60^{\circ}C$. These experimental procedures were triplicated to determine the in vitro digestibility of dry matter, crude fiber, ADF, NDF, crude protein and pH. Compared to control diet, not added Aspergillus oryzae, the DM digestibility of fungal diets were improved 2.1%(63.1%), 9.7%(68.5%) and 9.0%(68.0%) for 24 hour fermentation in compound feed while 4.8%(60.0%), 6.4%(61.1%) and 2.9%(58.8%) in TMR. On the contrary, for 48 hour and 72 hour digestibilities, the effects of Aspergillus oryzae culture on the digestibility of dry matter were relatively lowered compared to 24 hour digestibility. Referring to the digestibility of dietary fiber, Aspergillus oryzae was believed to significantly improve digestibilities of crude fiber, ADF and NDF. Those were increased up to 13.3%(53.3%) for 24 hour fermentation, while 2.4%(54.6%) for 3.0% added for 72 hour fermentation in compound feed. However, there were no significant differences among the treatments for the inclusion rate of Aspergillus oryzae, even though the more inclusion rate, the better digestibility. The protein digestibilities were significantly improved from 0.4%(79.7%) to 9.4%(71.8%) by adding Aspergillus oryzae into compound feed. However, there were no significant differences between the two experimental diets, 2.0% and 3.0% Aspergillus oryzae included diets. In case of TMR, the protein digestibilities were significantly improved from 4.0%(70.4%) to 6.3%(65.1%) by adding Aspergillus oryzae. However, there were no significant differences between the two experimental diets, 2.0% and 3.0% Aspergillus oryzae included diets. In this study, there were no significant differences among the treatments in pH. On the contrary, there were slightly decrease in pH by adding Aspergillus oryzae into experimental diets but not significant. Summarizing the results of this examination, Aspergillus oryzae fermentation culture is believed to improve the digestibilities of dry matter, fiber and crude protein in cattle diets. However, more detailed research for the mechanism of the fungal culture is required to improve ruminal environment.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.65-67
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• 1998

내장 실시간 시스템이 높은 우선순위의 비동기적 이벤트를 적시에 처리하면서 필수적으로 적은 비용의 선점 다중쓰레드를 지원해야한다. 사용자 레벨 쓰레드는 커널 레벨 쓰레드 보다 적은 비용의 유연한 추상적 기법들을 제공하지만, 기존의 실시간 시스템에서는 스케줄링과 시그날(signal) 처리가 단순하다는 이류로 커널 레벨 쓰레드가 선호 되어왔다. 본 논문에서는 내장 실시간 시스템에 적합한 새로운 사용자 레벨 다중 쓰레드 방식을 제안한다. 이 기법은 가상 쓰레드(virtual threads)와 개선된 스케줄링 이벤트 업콜(scheduling event upcall) 메카니즘을 기반으로 한다. 가상 쓰레드는 사용자 레벨 쓰레드에게 커널 레벨의 실행 환경을 제공할 수 있도록 사용자 레벨 쓰레드를 커널 레벨로 형상화한 것이다. 이 쓰레드는 필요에 의해 잠시동안 사용자 레벨 쓰레드에 묶이는 소동적인 존재이다. 스케줄링 이벤트 업콜 메카니즘은 쓰레드 블록킹과 타이머 만기와 같은 커널 이벤트를 유저 프로세서에게 전달할 수 있게 한다. 본 논문의 개선된 업콜 방식은 scheduler activation과 시그날과 같은 전통적인 업콜 구조에서 예측하기 힘든 요소들을 배제했다. 순간적인 시스템의 과부하 상황에서도 이벤트를 놓치지 않으면서 커널과 유저 프로세서의 비싼 동기화 작업들을 피할 수 있도록 하는 잠금(lock)이 필요 없는 이벤트 큐를 상용한다. 본 기법은 서울대학교 실시간 운영체계 실험실에서 구현한 ARX위에 완벽하게 구현되었다. ARX 사용자 레벨 쓰레드가 사용자 레벨 쓰레드의 장점을 손상하지 않으면서 솔라리스와 윈도즈98과 같은 상용 운영체제의 커널 쓰레드보다 성능이 우수함을 실험적 비교에 의해서 입증한다.분에서 uronic acid를 분리동정하였을 때 점미는 0.90%, 백미는 0.66%, 흑미는 1.8%로서 흑미에서 uronic acid 함량이 두 배 이상으로 나타났다. 흑미의 uronic acid 함량이 가장 많이 용출된 분획은 sodium hydroxide 부분으로서 hemicellulose구조가 polyuronic acid의 형태인 것으로 사료된다. 추출획분의 구성단당은 여러 곡물연구의 보고와 유사하게 glucose, arabinose, xylose 함량이 대체로 높게 나타났다. 점미가 수가용성분에서 goucose대비 용출함량이 고르게 나타나는 경향을 보였고 흑미는 알칼리가용분에서 glucose가 상당량(0.68%) 포함되고 있음을 보여주었고 arabinose(0.68%), xylose(0.05%)도 다른 종류에 비해서 다량 함유한 것으로 나타났다. 흑미는 총식이섬유 함량이 높고 pectic substances, hemicellulose, uronic acid 함량이 높아서 콜레스테롤 저하 등의 효과가 기대되며 고섬유식품으로서 조리 특성 연구가 필요한 것으로 사료된다.리하였다. 얻어진 소견(所見)은 다음과 같았다. 1. 모년령(母年齡), 임신회수(姙娠回數), 임신기간(姙娠其間), 출산시체중등(出産時體重等)의 제요인(諸要因)은 주산기사망(周産基死亡)에 대(對)하여 통계적(統計的)으로 유의(有意)한 영향을 미치고 있어 $25{\sim}29$세(歲)의 연령군에서, 2번째 임신과 2번째의 출산에서 그리고 만삭의 임신 기간에, 출산시체중(出産時體重) $3.50{\sim}3.99kg$사이의 아이에서 그 주산기사망률(周産基死亡率)이 각각 가장 낮았다. 2. 사산(死産)과 초생

• Development and Reproduction
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• v.12 no.2
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• pp.133-139
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• 2008

The eggs of Luciogobius grandis attached beneath the small stone were collected at Ocheon-dong, Yeosu-city from February to May, 2006. We carried them to the laboratory of Chonnam National University to investigate their development. The fertilized eggs were elliptical in shape (mean long axis: $2.06{\pm}0.23\;mm$; mean short axis: $0.74{\pm}0.04\;mm$) and transparent. There were filaments on the egg membrane. Their hatching was occurred at 120hrs 54mins after the morula stage at $18.4{\sim}21.0^{\circ}C$ (mean $19.4^{\circ}C$). The newly hatched larvae were $3.30{\pm}0.07\;mm$ (n=30) in total length (TL), with $34{\sim}36$ myotomes, and their mouth and auns were already open. Their melanophores were appeared over the gas globule, around the anus and a part of caudal peduncle. At 9 days after hatching, the larvae was $5.06{\pm}0.18\;mm$ (n=30) in TL and transformed to postlarval stage with yolk absorption. At 29 days after hatching, the larvae attained full fin ray count and reached the juvenile stage with $11.46{\pm}0.12\;mm$ (n=30) in TL.

• Development and Reproduction
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• v.10 no.1
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• pp.41-45
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• 2006

The spawning behavior of Liobagrus obesus was observed at Kumgang river, Yeongdong-gun, Chungcheongbuk-do from Apirl to July 2004. The fertilized eggs collected by dip net and skimming net were carried to the laboratory of Chonnam National University, and then egg, larvae and juvenils development were studied. Hatching of the embryo began about at 225 hrs 15 mins after morula stage in water temperature of $19.5{\sim}24.9^{\circ}C$(mean $22.8^{\circ}C$). The newly-hatched larvae were $7.30{\sim}7.90mm$(mean 7.66mm) in total length (TL), their mouth and anus were already opened with 14+28=42 myotomes. Sixteen days after hatching, the postlarvae were $13.00{\sim}14.05mm$(mean 13.48mm) TL, the yolk sac was completely absorbed. The juvenile stage was reached when all fin-rays were formed at 24 days after hatching, and $15.31{\sim}17.20mm$(mean 16.31mm) TL.

• Journal of Advanced Navigation Technology
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• v.3 no.2
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• pp.108-119
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• 1999

In recent, there has been remarkable progress in the field of GPS applications. In a few years, an appreciable number of aircraft will adopt GPS as a landing guidance system because GPS is more economic, more reliable and more accurate than any other aviation systems. In this respect, we have performed several helicopter landing flight tests based on the real-time DGPS system made in SNUGL (Seoul National University GPS Laboratory). From the experimental results, we found several problems Which should be fixed to adopt DGPS as a aircraft landing guidance system. In this paper, we will introduce the problems found in tests and also suggest modifications to solve the problems. Our modifications can be classified into three parts. The first is about the attitude determination with single GPS antenna. The second deals with the cockpit display module. The display was devised to integrate the Instrument Landing System(ILS) with tunnel-the-sky using virtual reality. With the display, pilot can achieve more safe landings. The last part is the digital map. We inserted digital map into our system and put direction indicator on the map using position information from GPS. It is very useful for pilot to find airports even in bad weather. Using the newly designed DGPS landing system, we conducted flight test at Kimhae International Airport, Pusan, Korea. It was successful! Our system can also satisfy Category-I criterion for aircraft landing approach and determine attitude angle with a high level of reliability. It is supported by video materials.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.264-269
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• 1984

The single edged blade was efficient to reduce tilling torque requirement than the double edged blade as previous reported study. This study was carried out to find reducing effects of tilling torque requirement of single edged blade comparing to double edged one in according to wearing by tilling operation. The single and double edged rotary blades were attached on same rotary shaft, and tilling operation was done in hard glass land. The wearing weights of the blade were checked out each 3 hrs tilling operation, at same time, the tilling toruqe requirements were measured with soil bin system in laboratory. The results of the study were summarized as follows: 1. The edged blade shape was not changed during the tilling operation of the rotary blade. The single edged blade was saved 5-10% in the maximum tilling torque and 3-15% in the mean tilling torque than the double edged blade for total durable period. 2. Generally, the tilling torques according to operation were decreased until original shape was maintained, but it was increased after 12 hrs tilling operation, and the tip shape of rotary blade was changed seriously. It is noted that the tip shape of the rotary blade is another factor affecting tilling torque, it should be desirable to study on the rotary blade tip shape to reduce tilling torque requirement after changing its original shape with wearing.

• Korean Educational Research Journal
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• v.38 no.3
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• pp.167-188
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• 2018

The purpose of this study is to suggest safety education on life science inquiry activity, which subjects on the exploration and autonomous research to the relevant topics, mainly done by the science high school students. Investigation was made on subjects of research activity proposed from Life science and autonomous research from science high school students by examine thoroughly 2009 revised education curriculum. To prevent school laboratory accidents, education of basic safety regulations and general precautions should be repeatedly notified by clear statements and expression to each topic. Expressing the safety factors considering the themes of autonomous inquiry and activities presented in the course of education should be done, so that students should not experience laboratory accidents by reason of ignorance. From the beginning of organization to performing research, safety rules about disposing chemicals and tools wastes occurring during research should be noticed and expressed in precautions following waste disposal system should be adopted. It is necessary to level up the accessibility of information about the laboratory safety rules to confirm to the every student, and also ensure the takeover of the clean-up and use of utilities at the time of search end in order to prevent the incidence of laboratory accidents during the thorough stages of biological inquiry activities.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.173-180
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• 2015

A passive type of fence security system was developed, which was based on electric charge detection technique. The implemented fence security system was installed at outskirts of greenhouse laboratory in the University of Seoul. The purpose of this research is to minimize false alarms by analyzing environmental noise. The existing system determines the intrusion alarm by analyzing the power of amplified signal, but the alarm was seriously affected by natural strong wind and heavy rainfall. The SAU(Signal Analysis Unit) sends input signals to remote server which displays intrusion alarm and stores all the information in database. The environmental noise such as temperature, humidity and wind speed was separately gathered to analyze a correlation with input signal. The input signal was analyzed for frequency characteristic using FFT(Fast Fourier Transform) and the algorithm that differentiate between intrusion alarm and environmental noise signal is improved. The proposed algorithm is applied for the site for one month as the same as the existing algorithm and the false alarm data was gathered and analyzed. The false alarm number was decreased by 98% after new algorithm was applied to the fence. The proposed algorithm improved the reliability at the field regarding environmental noise signal.