After the Fukushima disaster, overseas nuclear power plants have established conditions for issuing a red alert in the event of fuel damage within the spent fuel pool and they have already implemented conditions for issuing a blue alert when fuel is exposed above the water surface. In South Korean nuclear power plants, a real-time monitoring system is in place to oversee the exposure of spent fuel to the surface within the spent fuel pool. To achieve this, a water level indicator gauge is installed within the spent fuel pool, allowing for continuous real-time monitoring. This paper conducted a comparative assessment of radiation levels from water level monitoring system in two units’ spent fuel pools based on the low water levels (1 feet from the storage rack), utilizing the radiation analysis code (MCNP).

해양산업시설에서는 많은 종류의 유해물질의 배출 가능성이 존재하기 때문에 이에 대한 체계적인 대응체계가 필요하다. 그 중 연속자동 측정이 가능하면서 ppb 수준의 낮은 검출하한 (limit of detection:LOD)를 갖는 센서 구현은 매우 중요하다. 이를 위해 본 연구에서 는 활성탄소(carbon black)와 Indium tin oxide (ITO) 나노입자를 혼합한 film의 표면저항의 변화를 이용한 고성능 센서 제안 및 구현을 위해 성능인자를 최적화하였다. 센서 구조는 접촉 면적과 전극 간격을 최적화하였다. 접촉 면적이 증가하면 감도, LOD 성능이 향상되었으며 60 mm2에서 최적화되었다. 또한, 전극 간격은 접촉 면적을 일정하게 유지한 상태에서 변화시켰으며 센서 응답은 전극 간격이 감소함에 따라 증가하는 것을 확인하였다. 마지막으로 센서 표면에서의 유해물질의 잔류시간 증가를 위해 화학흡착제를 적용하였다. 화학흡착제는 유해 물질을 선택적으로 흡수할 수 있는 polyester계를 선택하였다. 그 결과 농도가 증가함에 따라 응답이 선형적으로 증가하여 센서로 활용이 가능한 것을 확인하였다. 이러한 3가지의 방법을 통해 센서를 제작하였을 때 액상 유해물질을 기존 센서의 LOD(89.9 ppb)와 비교 10~40 ppb 정도의 낮은 농도를 검출할 수 있는 센서를 구현하였다.

본 연구는 저염분 상태에서 수온 및 사육밀도와 같은 환경요인이 흰다리새우(Litopenaeus vannamei)의 성장에 미치는 영향을 조사하기 위하여 수행하였다. 연구 결과, 흰다리새우는 저 염분 상태에서 전반적으로 수온이 높을수록 생존율이 높게 나타났고, 사육밀도가 낮을수록 생 존율이 높아졌다. 사료효율에 관한 연구에서는 수온이 높을수록 증체량(WG)이 증가하였고, 사 육밀도가 증가할수록 증체량은 감소하였다. 수온이 높을수록(수온 31℃) 성장 속도가 빨랐다. 또한 사육밀도에 따른 성장도의 평가에서도 사육밀도가 낮은 상태에서 성장 속도가 빨라지는 것을 확인하였다. 본 연구 결과를 흰다리새우의 최적 성장을 위한 적정 사육밀도 및 사육수온 의 결정에 유용하게 적용되리라 사료된다.

During the winter of 2017/2018, significantly low water temperatures were detected around the western and southern coasts of Korea (WSCK). In this period, sea surface temperature (SST) in the Korea Waters was about 2℃ lower than mean temperature. Using the real-time observation system, we analyzed the temporal variation of SST during this period around the western and southern coasts. Low water temperature usually manifested over a period of about 10 ~ 20 days. The daily Arctic oscillation index was also similarly detectable with the variation of SST. From the cross-correlation function, we compared two periodic variations, which were SST around the WSCK and the Arctic oscillation index. The cross correlation coefficients between both variations were approximately 0.3 ~ 0.4. The time lag of the two time series was about 6 to 7 days. Therefore, significanlyt low water temperatures during winter in the Korean coastal areas usually became detectable 6 to 7 days after the negative peak of Arctic oscillation.

Chlor-alkali (CA) membranes as key materials to generate chlorine gas and sodium hydroxide are composed of sulfonic acid layer (S-layer) and carboxylic acid layer (C-layer) to provide fast sodium ion transport and slow hydroxide ion diffusion, respectively. Aciplex F, a representative CA membrane is made in a double layer form via thermal adhesion of both layers after each single layer film is independently fabricated. Unfortunately, the membrane fabrication induces delamination particularly in their interface as a result of hydroxide ion diffusion occurring during CA operation, leading to rapid increase in electrochemical overpotential. In this study, selective chemical conversion technique was developed to solve the delamination issue. Their effectiveness was proved by applying the same concept to a wide range of PFSA membrane.

This study evaluated the ecotoxicological properties of livestock waste water treated by a LID (Low Impact Development) system, using a mixture of bio-reeds and bio-ceramics as suitable bed media for a subsequent treatment process of a livestock wastewater treatment plant. The relationship between the pollutant reduction rate and the ecotoxicity was analyzed with the effluents from the inlet pilot plant, with vegetated swale and wetlands and the batch type of an infiltration trench. Each pilot plant consisted of a bio process using bio-reeds and bioceramics as bed media, as well as a general process using general reeds and a bed as a control group. The results indicated that, after applying the HRT 24 hour LID method, the ecotoxicity was considerably lowered and the batch type pilot plant was shown to be effective for toxicity reduction. The LID method is expected to be effective for water quality management, considering ecotoxicity by not only as a nonpoint source pollution abatement facility but also, as a subsequent treatment process linked with a livestock manure purification facility. It is necessary to take the LID technic optimization study further to apply it as a subsequent process for livestock wastewater treatment.

본 연구는 참굴(Crassostrea gigas)의 패각운동을 이용하여, 연안역에서 발생하는 저염수에 대한 조기경보가능성을 살펴보았다. 30 psu와 20 psu에서 패각운동은 각각 7.32±3.21회/hr와 7.11±3.90회/hr였으며, 파형과 횟수는 차이가 없었다(t-test, p>0.001). 하지만 10 psu와 5 psu 에서는 모든 개체가 폐각상태를 지속하였다. 수온과 염분의 복합실험결과, Group 1(수온 15 ×염분 15 psu)은 20 30 psu에서 보인 패각운 동 후(약 2 3시간), 장시간 폐각을 하였다. Group 2(수온 30 ×염분 15 psu)에서는 Group 1의 패각 개폐운동보다 더 빠르고 자주 나타나, 참 굴의 생리적인 위기상황에 대한 신호를 나타내었다. 따라서 이러한 파형은 하계 저염수 출현 시 나타낼 수 있는 조기경보 신호로 충분히 활용될 수 있을 것으로 보인다.

In this study, the land use is analyzed by using the SWMM-LID (Low Impact Development) program to minimize the environmental damage caused by the development. In order to effectively utilize pre - development hydrological conditions, we analyzed the land use of existing industrial complex. The study areas selected were a completed industrial complex and an ongoing industrial complex in order to effectively identify the characteristics of the industrial complex and the water circulation system. Numerical simulation used SWMM-LID to enable quantitative hydrological impact assessment of penetration, storage facilities and LID planning elements. In the case of natural conditions, the infiltration amount was 16.3% and 1.5% of the total rainfall at B, C point, respectively. However, after applying the existing land use plan, the infiltration amount at point B was 12.1% and at point C was 3.9 %. In the case of point B, the amount of infiltration decreased due to the development of greenery as an impervious site. On the other hand, the amount of infiltration at point C increased as the existing industrial complex was replaced by greenery. Therefore, high infiltration amount can be secured when land use plan is redeveloped in green areas or parks in areas where the permeability coefficient is high according to the ground conditions in the complex. Two types of bio-polymer soil were developed to increase the LID effect and were tested to compare typical soil with these bio-polymer soils.

In this study, the physicochemical and sensory characteristics of low-salt Myungran jeotkal (Alaskan pollock roe) were evaluated after fermentation at 4℃ and 20℃ with or without the addition of deep sea water, salt from deep sea water, and vegetable-origin lactic acid bacteria (Lactobacillus fermentum JS, LBF). When fermented at 20℃, the addition of LBF to Myungran jeotkal resulted in a slow increase in lactic acid content, followed by an abrupt increase after five days of fermentation. However, when fermented at 4℃, the lactic acid content did not change significantly. Further, when Myungran jeotkal fermented at 4℃, the pH decreased as lactic acid production increased. The salinity of Myungran jeotkal fermented at 4℃ and 20℃ was 7% and was not affected by fermentation period. When fermented at 20℃, volatile basic nitrogen and amino nitrogen contents increased with increasing duration of fermentation. Further, volatile acid content decreased, however, the content of amino nitrogen increased after 11 days of fermentation with LBF and no salt effects were observed. When fermented at 20℃ for 13 days, preference (sensory evaluation) was the highest in all experimental groups after 9 days of fermentation, and then decreased as the fermentation period increased. The free amino acid content was highest (1,648.8 mg/100 g) in Myungran jeotkal when sun-dried salt and LBF were added, 2.3 times higher than in the control.