PURPOSES : This study sought ways to connect urban above ground roads and underground roads to utilize urban space more efficiently in the development of underground roads, which are currently under development in order to alleviate problems caused by oversaturated above-ground roads. A simulation analysis was performed to develop an operation strategy that connects above-ground and underground roads to prevent congestion in above-ground areas such as entrances and exits from transferring to underground roads as well as to present its effectiveness. METHODS : Traffic efficiency analysis according to the operation strategy of above ground and underground roads was conducted using VISSIM, a microscopic traffic simulation software. The functions implemented in VISSIM were collected to set effectiveness analysis indicators for each underground road operation strategy. The Shinwol-Yeoui Underground Road was selected as the spatial scope of this study, and a surrounding road network was constructed. In addition, full-scale simulation analysis preparations were completed by performing network calibration based on the actual traffic attribute data of underground and surrounding surface roads within the construction scope. Accordingly, a traffic efficiency evaluation analysis was conducted based on the underground road operation strategy. CONCLUSIONS : Information on the increase in traffic volume within the Shinwol-Yeoui underpass was collected every 15 min. The analysis was divided into an analysis of the traffic situation within the underpass through demand control when the service level reached level D and an analysis of when demand control was not performed. It was found that demand control was necessary for the Shinwol-Yeoui Underpass when the internal traffic volume reached 2,500 vehicles/h. In addition, to analyze the spread of traffic and congestion owing to the weaving phenomenon caused by lane changes in the underpass, an analysis was conducted to observe the traffic improvement effect when full lane changes are possible for the Shinwol-Yeoui Underground Road, which currently has some lane-change-permitted sections. The analysis showed that both the maximum traffic volume and average travel speed showed better results when lane changes were allowed, and the communication situation at Yeoui JCT was found optimal.

In this study, we investigated the microstructure and piezoelectric properties of 0.96(K0.456Na0.536)Nb0.95Sb0.05-0.04 Bi0.5(Na0.82K0.18)0.5ZrO3 (KNNS-BNKZ) ceramics based on one-step and two-step sintering processes. One-step sintering led to significant abnormal grain (AG) growth at temperatures above 1,085 °C. With increasing sintering temperature, piezoelectric and dielectric properties were enhanced, resulting in a high d33 = 506 pC/N for one-step specimen sintered at 1,100 °C (one-step 1,100 °C specimen). However, for one-step 1,115 °C specimen, a slight decrease in d33 was observed, emphasizing the importance of a high tetragonal (T) phase fraction for superior piezoelectric properties. Achieving a relative density above 84 % for samples sintered by the one-step sintering process was challenging. Conversely, two-step sintering significantly improved the relative density of KNNS-BNKZ ceramics up to 96 %, attributed to the control of AG nucleation in the first step and grain growth rate control in the second step. The quantity of AG nucleation was affected by the duration of the first step, determining the final microstructure. Despite having a lower T phase fraction than that of the one-step 1,100 °C specimen, the two-step specimen exhibited higher piezoelectric coefficients (d33 = 574 pC/N and kp = 0.5) than those of the one-step 1,100 °C specimen due to its higher relative density. Performance evaluation of magnetoelectric composite devices composed of one-step and twostep specimens showed that despite having a higher g33, the magnetoelectric composite with the one-step 1,100 °C specimen exhibited the lowest magnetoelectric voltage coefficient, due to its lowest kp. This study highlights the essential role of phase fraction and relative density in enhancing the performance of piezoelectric materials and devices, showcasing the effectiveness of the two-step sintering process for controlling the microstructure of ceramic materials containing volatile elements.

This study analyzed the monitoring results of fishways at 16 weirs constructed on four large Rivers to provide data helpful for the operation and management of fishways. The average utilization rate of the fishways at the weirs was confirmed to be 64.9%. When comparing the dominant species in the mainstream and fishway monitoring results, differences were observed in 9 weirs (56.3%). This indicated that the species prevalent in the mainstream were not necessarily the ones most frequently using the fishways. The average number of individuals using the fishways per day was 336. When classifying the fish species using the fishway by life type, 92.3% were primary freshwater fish, and migratory species accounted for only 5.6%. Analysis based on the season of fishway usage revealed that an average or higher number of fish species used the fishways from May to October, with the highest number of individual users occurring from June to August. Between May and July, 80% of the fish species using the fishways were in their spawning period, while during other season, less than 40% were species that move during the spawning period. The fishways that showed a significant alignment between the spawning period and the fishway passage period were Rhinogobius brunneus, Leiocassis nitidus, Squalidus chankaensis tsuchigae, Pseudogobio esocinus, Acheilognathus rhombeus, and Pungtungia herzi, in that order. When comparing the fishway monitoring results of the Gangjeong-Goryeong Weir and the Dalseong Weir with the upper part water level of the weir, both the number of fish species and individuals using the fishway showed positive correlations with the upper part water level of the weir. This suggests that a higher water level of the weir increases the inflow discharge within the fishway, leading to increased use by fish (number of individuals in Gangjeong-Goryeong Weir, P<0.001; number of species in Dalseong Weir, P<0.05). This study summarized and analyzed the results of fishway monitoring at 16 weirs built on four large Rivers, considering fishway efficiency, operation and management, monitoring period, and regulation of water level in the upper part of the weir. It is thought that this will help understand the status of fish use in fishways on large River and aid the construction, operation, and management of fishways in the future.

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries (78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.

This study was conducted on October 23, 2020 at the Cheongpyeong Reservoir located in Seorakmyeon, Gapyeong-gun, Gyeonggi-do, and analyzed the horizontal and vertical distribution patterns of fish based on data obtained using fishfinder. The total surface area of fishfinder survey conducted was 782,853 m2, and where the water depth (WD) ranges from 10 m to 12 m is widest which 31.7% of total surface area. As a result of the heat map analysis, fish density was highest at right bank under the Gapyeong-bridge, but there was no specific pattern in horizontal distribution of fish. As a result of vertical distribution of fish analysis, 86.6% of fishes are observed at below 6 m of the fish depth (FD, distance from water surface to fish). As a result of the relative height (RH, water depth-distance from bottom to fish ratio) analysis, there was a tendency that fishes are distributed in near surface area more as the WD increased. This tendency could have various reasons such as water temperature gradient along the water depth, and further studies are required for detailed explanation.

본 논문은 지상파 기반의 측위·항법·시각(PNT, Positioning, Navigation, and Timing) 서비스의 대표격인 eLoran(enhance LOng RAnge Navigation) 시스템의 시각동기 성능 모니터링 시스템의 설계에 관한 것으로서, GNSS(Global Navigation Satellite System)의 신호 취약성에 따른 시각동기시스템의 한계에 대해 설명하고, 이에 대한 백업시스템으로 대표적 지상파항법시스템인 eLoran 시스템의 시각동기 성능모니터링 시스템에 대해 중점적으로 다룬다. eLoran 시스템을 이용한 시각동기 서비스 및 이에 대한 성능감시를 위한 보정기준국(dLoran, differential Loran) 관점에서의 시각동기 성능모니터링 시스템의 구성과 그 요구성능에 대해 설명한다. 또한 eLoran 테스트베드 환경 내 시각동기 모니터링 시스템의 장기 시범운영을 통해서, eLoran 시각동기서비스의 성능을 분석한다. 시각동기 성능모니터링 시스템을 이용한 성능 분석결과 보정 전 43.71 ns, 보정 후 22.52 ns (rms)의 시각정밀도를 나타내었으며, 이를 통해서 정밀시각 동기원으로 eLoran 서비스가 충분히 GPS 백업 시각동기시스템으로 활용이 가능함을 확인할 수 있었다.

국제해사기구는 항해 목적으로 사용 가능한 위성항법시스템의 요구 성능을 명시적으로 규정하고 있다. 2019년 이전까지 국제 해사기구는 항해용으로 이용이 가능한 위성항법시스템에 전지구 서비스가 가능한 시스템만을 인정해 왔으나, 최근 인도 지역위성항법시 스템을 승인하면서 지역위성항법시스템도 해양 이용이 가능해졌다. 지금까지 국제해사기구는 GPS를 비롯해 총 5개의 위성항법시스템, GLONASS, Galileo, BeiDou, NavIC 이용을 승인하였다. 우리나라에서는 NavIC을 제외한 4개 위성항법시스템 이용이 가능할 뿐만 아니라 아직 승인을 받지 못한 일본의 지역위성항법시스템, QZSS의 수신도 가능한 상황이다. 일본은 QZSS의 해양이용을 본격화하기 위해 국제해 사기구에 QZSS의 WWRNS 승인을 요청하였다. QZSS의 이용범위는 일본 영해에 한정하지 않고, 우리나라 관할해역을 포함하고 있다는 점에서 해사안전을 위해 QZSS 국내 이용의 적합성 분석은 매우 중요하다고 할 수 있다. 본 논문은 국내 항해를 위한 QZSS 활용에 적합성을 분석하고자 한다. 이를 위해 QZSS 서비스 현황과 계획에 대해 먼저 알아보고, WWRNS로 인정을 받기 위해 국제해사기구가 요구하는 성능에 대해 살펴본다. 그리고 적합성 분석을 위해 본 논문에서 수행한 방법과 환경조건에 대해 설명하고, 측위정확도와 가용성 측면에서 분석된 결과를 제시하며, 분석결과가 갖는 의미에 대해 논한다.

본 연구는 환경부 멸종위기야생생물 1급으로 지정되어 있는 남방동사리의 분포와 서식지 특성을 확인하였다. 조사는 남방동사리의 주요 서식지로 알려져 있는 산양천 수계 (산양천, 구천천, 유입 지천)에서 이루어졌으며, 2016년 4월과 8월에 현장조사가 이루어졌다. 조사 결과 산양천 하류 S1~S3 지점을 제외한 전체 지점에서 남방동사리의 서식이 확인되었다. 서식 범위가 유입지천의 최상류에서 염도의 영향을 받지 않는 산양천 최하류까지이며, 남방동사리가 1차담수어이기 때문에 염도가 서식에 가장 큰 제한 요인이었다. 이외 서식처 및 산란처로 활용되는 하상구조가 중요한 요인으로 확인되었으며, 서식이 확인된 모든 지점에서 작은돌 (cobble) 크기 이상이 50% 이상을 차지하였다. 남방동사리의 상세한 분포지역이 본 연구에서 처음 보 고가 될 정도로 국내 서식하는 남방동사리에 대한 연구가 매우 부족하다. 따라서, 이러한 남방동사리의 보호 전략을 마련하기 위해서는 남방동사리의 생리, 생태에 대한 과학 적인 연구가 이루어질 필요성이 있다.

This study was conducted to assess the effect of acidification of pig slurry on nitrogen (N) mineralization and its environmental impacts during pig slurry fermentation. Different inorganic and organic acids were used to acidify pig slurry. Four treatments including non-acidified pig slurry (control), pig slurry acidified with sulfuric acid, lactic acid, and citric acid were allocated with three replications. The total N content in the acidified pig slurry was higher than non-acidified pig slurry after fermentation. Acidification tended to increase total N content in pig slurry. Ammonium N (NH4 +-N) released from pig slurry was obviously increased at 7 days after incubation, representing 61.4%, 36.8%, and 37.4% increase in the acidified pig slurry with sulfuric acid, lactic acid, and citric acid, respectively. Nitrate N (NO3 --N) in the acidified pig slurry with sulfuric acid was the highest throughout the experiment period, but non-significant effect of organic acid. A large portion of ammonia (NH3) emission occurred within 10 days, corresponding to more than 55% of total NH3 emission. Total cumulative NH3 emission during the experimental period was lower 91% (2.9 mg N kg-1), 78% (7.3 mg N kg-1), and 81% (6.2 mg N kg-1) in the acidified pig slurry with sulfuric acid, lactic acid, and citric acid, respectively, than non-acidified pig slurry (32.7 mg N kg-1). These results suggest that acidification of pig slurry (particularly with sulfuric acid) can be faced as a good strategy to reduce NH3 emission without depressing the mineralization process.

위성신호 반사계측(GNSS-Reflectometry) 기술은 위성으로부터 전송되는 신호의 지표면 혹은 해수면에 반사되는 신호를 측정하여 분석하는 기법으로서, 해수면 높이측정, 태풍 및 기상이변, 그리고 토양의 수분 및 적설량 측정 등에 활용되고 있다. 본 논문에서는 GNSS-R 기술의 해양 활용확대와 그 가능성을 살펴보기 위하여, 위성신호의 신호대잡음비를 이용하는 GNSS-R 기술의 개념과 측정원리에 대해 설명하고, 국제적인 활용 사례를 조사하여 제시하였다. 특히 GNSS-R 기술을 기존 DGNSS 기준국 및 상시관측소 인프라를 이용하여 해양안전 및 환경 모니터링에 활용 가능할 뿐만 아니라, 지상 및 해양기준국, 위성기반, 해상선박 탑재 측면에서의 해양 응용 가능분야를 조사하여 제안하였다.

PURPOSES : The purpose of this study is to derive specific road design elements for safe urban underground and to adopt measures for minimizing traffic delays and to maintain efficient operation. METHODS : In this study, a qualitative study was conducted using Focus Group Interview (FGI) method to identify significant connection characteristics and develop connections to urban underground roads. Finally, this study analyzes design elements necessary for traffic safety and efficient traffic operation. In addition, relevant case studies were performed with keywords from the FGI method results. Therefore, major design elements were analyzed for urban underground road connection and connection analysis for traffic simulation-based verification. RESULTS : The main characteristics of the connection between the underground roads of the downtown area were divided into three types: traffic flow characteristics, geometric characteristics, and driver behavioral characteristics. From the review of 16 leading studies (10 domestic papers and 6 international papers) according to the characteristics, the main design factors for “traffic flow characteristics” include the traffic volume, design speed, heavy vehicle ratio, and lane change. The important design elements for “geometric characteristics” include the separation distance, number of lanes, slope, lane and shoulder width and the design factors for “driver behavioral characteristics” showed reaction time, driver vision, and driving speed. CONCLUSIONS : The FGI method identified the main characteristics of connections to the underground roads. In addition, the relevant empirical and theoretical research data were considered in case studies, and the design elements were derived and separated spatially based on the features of each design element, establishing a point-specific design element guideline.

본 연구는 영산강·섬진강 수계에 위치한 16개 호소에 대해서 어류군집을 조사하고 호소별, 호소 규모별 어류군집 특성을 분석하였다. 조사 방법과 지점수는 환경부의 “생물측정망 조사 및 평가 지침”에 따라 이루어졌으며, 소형호, 중형호, 대형호로 구분하여 어류군집을 비교 분석하였다. 2018년 (7개 호소)에서 2019년 (9개 호소)에 이루어진 조사에서 총 13과 44종의 어류가 채집되었으며, 우점종은 치리 (Hemiculter eigenmanni, RA, 32.9%), 아우점종은 블루길 (Lepomis macrochirus RA, 31.4%)로 나타났다. 호소 규모에 따라 분석한 결과 소형호에서는 평균 (±표준편 차) 11±2.9종이 채집되었으며, 중형호는 14.3±2.1종, 대 형호는 22.7±0.6종으로 호소의 규모가 커질수록 출현 종수가 증가하는 양의 상관성을 나타냈다. 호소 규모별 어류 군집 요인은 총 6개 항목 (총 종수, 총 개체수, 풍부도, 초식 성종 개체수 비율, 육식성종 개체수 비율, 외래종 종수)에서 차이를 보였다 (P<0.05). 호소별 어류군집 유사도 분석 결과 16개 호소가 60%의 유사도에서 5개 그룹으로 구분 되었으며, 군집 유사도는 호소의 규모보다는 호소 간 거리, 수계, 호소의 발달 위치 및 환경유형이 영향을 미치는 것 으로 나타났다. 본 연구는 국내 호소의 어류군집 구조 이해에 도움이 될 수 있으며, 특히 영산강·섬진강 수계의 호소 관리 및 정책 마련에 기초자료로 활용될 수 있을 것이다.

본 연구는 wadeable stream (1차~4차 하천)을 대상으로 보의 유·무에 따른 어류군집의 차이를 분석하였다. 하천의 규모에 따른 차이를 분석하기 위해서 하천차수로 구분 하여 보의 유·무가 어류군집에 영향을 미치는지를 파악하였으며, 3차와 4차 하천에서 어류군집의 차이가 확인되었다 (P<0.005, PERMANOVA). 보의 유·무에 따라 총 출현 종수, 총 출현 개체수, 종 풍부도와 같은 요인들이 차이를 나타냈으며, 외래종, 고유종, 보호종 개체수의 경우 차이를 나타 내지 않았다. SIMPER 분석을 통해서 어류군집 차이에 주로 기여하는 종을 분석한 결과 해당 차수의 하천에 우점적으로 나타나는 피라미 (Zacco platypus), 참갈겨니 (Zacco koreanus), 돌고기 (Pungtungia herzi)와 같은 보편종으로 확인되었다 (contribution>5%). 이들 종은 모두 보가 있는 지점에 서 평균 상대풍부도가 높게 나타났으며, 보로 인해 변화된 환경이 이들 종에 대해서 주요 서식처를 제공하는 것으로 판단되었다. 본 연구는 전국 범위에서 보가 어류군집에 미치는 영향을 분석하여 경향성을 제시하였으며, 이러한 결과는 향후 보의 관리를 위한 연구에 효과적으로 활용할 수 있을 것이다.