• Journal of information and communication convergence engineering
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• 제20권1호
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• pp.49-57
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• 2022

Fertilizers have long been used to increase crop yields; however, farmers are still having difficulties in managing fertilizers for growing crops as well as economic problems. The conventional method of soil sampling and laboratory analysis to determine soil pH is time consuming and costly; therefore, a portable pH sensor is developed to characterize spatial or temporal variability within fields via rapid and dense data acquisition. The portable pH sensor comprises an electrode unit, a portable console, and a USB connector. The soil water content (SWC) and electrical conductivity (EC) affect the electrical resistance of soil. An artificial test soil is performed to evaluate the effect of SWC and EC on soil pH. The test results show that stable pH measurements are achieved at SWCs greater than 20 mL (16.3%). Regardless of the SWC, the electric potential difference (EPD) remains at 2.5 g of NaCl. As the EC increases in the soil samples, the EPD increases.

• 한국정보과학회 언어공학연구회:학술대회논문집(한글 및 한국어 정보처리)
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• 한국정보과학회언어공학연구회 2022년도 제34회 한글 및 한국어 정보처리 학술대회
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• pp.348-353
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• 2022

최근 신경망 기반의 언어모델이 발전함에 따라 대부분의 검색 모델에서는 Bi-encoder를 기반으로한 Dense retrieval 모델에 대한 연구가 진행되고 있다. 특히 DPR은 BM25를 통해 정답 문서와 유사한 정보를 가진 하드 네거티브를 사용하여 대조학습을 통해 성능을 더욱 끌어올린다. 그러나 BM25로 검색된 하드 네거티브는 term-base의 유사도를 통해 뽑히기 때문에, 의미적으로 비슷한 내용을 갖는 하드 네거티브의 역할을 제대로 수행하지 못하고 대조학습의 효율성을 낮출 가능성이 있다. 따라서 DRP의 대조학습에서 하드 네거티브의 역할을 본질적으로 수행할 수 있는 문서를 샘플링 하는 방법을 제시하고, 이때 얻은 하드 네거티브의 집합을 주기적으로 업데이트 하여 효과적으로 대조학습을 진행하는 방법을 제안한다. 지식 기반 대화 데이터셋인 MultiDoc2Dial을 통해 평가를 수행하였으며, 실험 결과 기존 방식보다 더 높은 성능을 나타낸다.

• 방송공학회논문지
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• 제21권6호
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• pp.957-964
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• 2016

요즘 들어, 3차원 콘텐츠의 수요는 지속적으로 증가하고 있다. 3차원 콘텐츠의 품질은 해당 장면의 깊이 정보에 큰 영향을 받기 때문에 정확한 깊이 정보를 얻는 것이 매우 중요하다. 카메라와 객체 사이의 깊이 정보는 적외선 센서를 이용한 계산을 통해 직접 얻을 수 있다. 최근 들어, KINECT 카메라와 같이 카메라와 물체 사이의 거리를 적외선이나 광신호를 이용하여 직접 측정하는 Time-of-flight (ToF) 기술을 사용하는 깊이 측정 방법이 널리 사용되고 있다. 이러한 방법은 카메라와 객체 사이의 깊이 정보를 실시간으로 획득할 수 있다는 장점을 갖지만, 획득된 깊이맵에 잡음이 발생하고, 깊이맵의 해상도가 낮다는 단점을 갖는다. 최근 들어, 이런 문제를 해결하기 위해서 양방향 결합 업샘플링 방법 (JBU) 이나 잡음 제거 업샘플링 방법 (NAFDU) 과 같은 필터 기반의 방법이 제안되었다. 그러나 이러한 필터 기반의 업샘플링 방법은 업샘플링된 깊이맵에 색상영상의 질감이 복사되는 문제가 발생한다. 이 논문에서는 이러한 문제점을 해결하기 위해 고차 정규화항을 이용하여 에너지 함수를 만들고, 이를 최적화하여 깊이맵을 업샘플링 한다. 또한, 색상과 깊이맵의 경계 정보를 고려한 경계 가중치항을 추가하여 질감 복사 문제를 해결한다. 실험 결과, 제안하는 깊이맵 업샘플링 방법이 기존의 방법에 비해 깊이 정보의 품질은 유지하면서, 질감 복사 문제를 효과적으로 해결할 수 있음을 확인했다.

• 수산해양기술연구
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• 제30권4호
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• pp.251-262
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• 1994

The speed of vertical migration and the volume backscattering strength of the scattering layers during the evening and morning transitions between day and night were measured in November 1990-1992 in thermally stratified waters of the East China Sea. Acoustical measurements were carried out using a scientific echo-sounder operating at t재 frequencies of 25 and 100kHz, and using an echo-integration system connected with a micro-computer. Biological sampling was accomplished by bottom trawling to identify fish species recorded on the echo sounder, and the species and length compositions were determined. The values of scattering strength were allocated to group of fishes according to the fish traces on the echo recording paper and the species composition of trawl catches. The vertical velocities of migration derived from the changes in the depths and the values of peak scattering strength of the dense layer vertically migrating toward the bottom or toward the surface. The trawl data suggest that snailfish and fishing frog were the most abundant fishes in all research stations. As sunrise approached, the fish formed a strong concentration just above the thermocline. The the highest values of scattering strength in the entire water column appeared in the depth strata above the thermocline just before the begining of downward migration. As soon as the fish began to migrate downwards across the thermocline, the values of the scattering strength in the depth strata above the thermocline rapidly decreased, while the values for the scattering layer moving slowly toward the bottom gradually increased. During the 1992 surveys, the speed of the vertical migration was estimated to be 0.38m/min in the upward migration and 0.32m/min in the downward migration, respectively. That is the rate of vertical migration was slightly higher at dusk than at dawn. Similar migration patterns were observed on different stations and under different weather conditions during the surveys in 1990.

• 한국물환경학회지
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• 제29권3호
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• pp.420-427
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• 2013

In this study, the ecological characteristics of Limnoperna fortunei were surveyed as a preceding research to solve the problem such as biofouling or biowaste caused by those organisms in the closed water pipeline. Limnoperna fortunei was collected not in the main reaches of Somjin River but inside and outside of the intake tower which is located in the lower part of Sueo Reservoir. The dense populations were found at the inlet mouth and near part of the pipeline. Their byssuses were formed as a thick and tightly interwind mat. The rusted parts of the pipeline hold relatively more shells than those of the normal parts. Average count of the numbers ranged $12.1{\sim}136.5ind./m^2$ through the sampling stations (A,B and C). The amount of attached shells at each station were A=386, B=258, and C=71, respectively. The relationships of shell height-length and shell length-width were proportional. The majority sizes in each station ranged A=20.01~22.00 mm (33.9%), B=10.01~14.00 mm (51.2%), and C=18.01~20.00 mm (22.5%), 24.01~26.00 mm (21.1%), respectively. Most of the bigger size of shells on C station was found dead. The ecological habitat seemed less suitable for Limnoperna fortunei when they located farther away from the intake tower of reservoir. From now on, it is necessary to consider the continuous monitoring of this organism.

• 한국전자통신학회논문지
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• 제15권5호
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• pp.835-840
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• 2020

본 논문은 수십시간이 소요되는 총복사전력(TRP) 측정 시간을 단축하는 방안을 컴퓨터 모의실험과 실제 실험을 통하여 검증한 결과를 제시하고 있다. 5G의 고주파수 대역에서는 무선통신기기의 정확한 성능평가를 위하여 TRP 측정이 기본적으로 수행되지만 촘촘한 샘플링 간격 때문으로 인하여, 긴 측정 시간이 소요되는 문제점을 가지고 있다. 더구나 다양한 빔 형성 시나리오를 갖는 경우 전체 측정 시간은 기하급수적으로 증가한다. 따라서, TRP 측정 시간 단축 방안이 필요하며, 그 일환으로 본 논문에서는 유효등방복사전력(EIRP)과 TRP 관계식을 이용하여 측정시간을 단축하는 방법을 다루었다. 먼저 TRP와 EIRP의 관계식을 관찰하고, 피시험용 안테나의 설계 및 제작하였으며 모의실험 결과와 측정결과를 통한 오차를 분석하였다. 그 결과 EIRP를 통하여 TRP를 산출한 결과는 매우 작은 오차를 가짐을 확인하였다. 본 방법은 향후 5G 무선통신기기의 TRP 도출에 적용할 수 있을 것으로 예상한다.

• 한국환경과학회지
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• 제23권5호
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• pp.973-984
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• 2014

Seasonal and stational variation of SS and COD were investigated from February 2008 to December 2010 and the relationship between them was discussed. During three years monitoring, SS decreased significantly (46% decline) possibly due to the increase of precipitation and thereby resulting salinity drop. COD on average was the highest in 2009. SS was the highest in autumn and the lowest in winter, and over 72% of SS was FSS. While SS is high in the upper sampling stations of the bay with shallow water, COD values do not show any relationship to the geomorphological characteristics. $COD_{ins}$, which was defined as COD after filtration, ranged 56%(winter) ~ 44.6%(summer) and showed no correlation with SS. It indicates that high SS concentration is not necessarily related to the high $COD_{ins}$. The seasonal $COD_{ins}$/SS data, which can be interpreted as COD density in SS, shows that SS in winter contains the dense COD materials compared to the other seasons.

• Journal of Nutrition and Health
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• 제39권8호
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• pp.841-849
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• 2006

This study compared the nutritional quality of Korean adults's consumption of lunch prepared at home, commercial places, and institutions. The one day food intake data collected via 24-hour recall in the 2001 National Health and Nutrition Survey were analyzed. Individuals with 19-64 years of age were selected (n = 5,756). Sampling weights in the Survey were used to generate nationally representative estimates. Lunch was categorized into three groups according to the place where the lunch was prepared. home, commercial places, and institutions such as schools and work places. Comparison among the three groups was made for 19-39 years old men (n = 1,387) and women (n =1,572) and 40-64 years old men (n = 1,364) and women (1,433), respectively. The lunch prepared away from home contained more calories. The lunch prepared commercially was higher in calories percentages from fat than that prepared either at home or at institutions. Across the age and gender groups, lunch prepared at home contribute a high level of sodium intake. Among individuals with 40-64 years of age, but not those with 19-39 years of age, lunch prepared commercially was as sodium dense as that prepared at home. Among individuals with 19-39 years of age, the sodium density of lunch prepared commercially was about the same as that prepared at institutional food service of which the menus were planned by dieticians. Such differences in nutritional quality among meals prepared at home, commercial places, and institutions should be considered and applied for the content development of nutrition education and policy.

• Asian Pacific Journal of Cancer Prevention
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• 제16권17호
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• pp.7607-7612
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• 2015

Aims: The purpose of our study was to evaluate the diagnostic performance of breast magnetic resonance imaging (MRI) in the evaluation of contralateral breast in patients with diagnosed breast cancer. A secondary objective was to determine accuracy of breast MRI in diagnosing multi-focal and multicentric lesions in the ipsilateral breast. Materials and Methods: Using a non-probability convenience sampling technique, patients with histopathologically diagnosed breast cancer with MRI of breast performed to exclude additional lesions were included. MRI findings were correlated with histopathology. In addition, follow-up imaging with mammography and ultrasound was also assessed for establishing stability of negative findings and for the detected of benign lesions. Results: Out of 157 MRI breast conducted during the period of 2008 to 2013, 49 were performed for patients with diagnosed breast cancer. The sample comprised of all females with mean age $50.7{\pm}11.0years$. The patient follow-up imaging was available for a period of 2-5 years. The sensitivity, specificity, and positive and negative predictive values of MRI in the detection of multifocal/multicenteric lesions was 85.7%, 88.8%, 60% and 96.6% respectively and for the detection of lesions in the contralateral breast were 100%, 97%, 83.3% and 100% respectively. Conclusions: Our study highlights the diagnostic performance and the added value of MRI in the detection of multifocal/multicenteric and contralateral malignant lesions. In patients with diagnosed breast cancer having dense breast parenchyma and with infiltrating lobular carcinoma as the index lesion MRI is particularly useful with excellent negative predictive value in the exclusion of additional malignant foci in the ipsilateral and contralateral breasts.

• 한국멀티미디어학회논문지
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• 제10권3호
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• pp.316-324
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• 2007

의료영상에서 사용하는 MIP 볼륨 렌더링은 CT나 MR 등의 볼륨데이터에서 시각 광선으로부터 높은 밝기 값을 추출하여 혈관과 뼈와 같은 환자의 조직을 보여주는 볼륨 렌더링 기법이다. 최근 GPU를 MIP 볼륨 렌더링에 사용하여 대용량 의료영상 데이터에 대해서도 속도가 빠른 렌더링이 가능하게 되었다. 볼륨데이터를 여러 각도에서 관찰하면, 일반적으로 시각과 동일한 방향의 텍스쳐 평면과 볼륨 경계평면이 비스듬하게 교차한다. 볼륨데이터의 외부에는 값이 존재하지 않으므로 경계부분에서 공간 주파수가 높게 나타난다. 기존의 MIP 렌더링은 샘플링 간격이 일정하기 때문에 경계부분에서 데이터의 손실이 생겨 알리아싱이 나타나는 문제가 있다. 화질을 개선하기 위해 샘플링 간격을 줄여 슬라이스수를 증가시킬 수 있으나, 이때는 렌더링 수행 시간이 길어지게 된다. 이 논문에서는 기존 렌더링 결과에 볼륨 경계 평면을 추가로 렌더링하는 방법을 제안한다. 이 방법은 주파수가 높은 경계 부분의 샘플링 간격을 줄여 화질을 향상시킨다. 한편 MIP는 샘플링 순서에 무관하므로 추가된 슬라이스는 기존 렌더링 영상을 손실시키지 않는다. 증가된 슬라이스는 경계부분인 여섯 평면에 불과하므로 렌더링 수행시간에는 거의 영향을 주지 않고 화질을 개선할 수 있다.