• Journal of Digital Convergence
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• v.20 no.5
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• pp.317-322
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• 2022

In general, life jackets are worn by people in critical situations on the water to rise to the surface without falling into water, and life jackets simply serve to prevent sinking, but do not actively help rescue disaster areas in critical situations early. In order to solve this problem, a device that automatically generates a distress signal in an emergency situation was developed. When the survivor is in hand for a while, the distress signal generator is automatically separated from the life jacket, allowing information such as location values and other information to be transmitted wirelessly and a rescue signal using LED light. As a result of the experiment, when submerged in water, the life jacket and the distress signal generator were automatically separated, and the result of wireless transmission of the coordinate value of the location received by the GPS was confirmed. By using this, the location of the distress or missing person can be identified, which can be quickly replaced in case of an emergency

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.18-18
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• 2022

하천 합류부에 있어 수체의 혼합양상을 분석은 고해상도의 자료가 필요하다. 반면에 수질환경 문제와 기존 모니터링 시스템이 고정된 측정 방식으로 이루어지기 때문에 하천 전체의 정보는 저해상도의 결과값은 나타낸다. 또한, 많은 수중 환경 문제가 1차원에서 3차원에 걸쳐 있지만, 대부분의 관측 시스템은 1차원에 머물러 있음을 확인할 수 있다. 이러한 문제를 해결하기 위해서는 보다 발전된 관찰 및 계측이 필요하다. 그에 따른 고해상도의 측정 자료를 얻기 위해서는 측정자가부담을 많이 가지며, 측정할 수 있는 영역이나 시간적으로 제한적이다. 해상도는 낮추되 광범위한 데이터를 취득하기 위해서는 적절한 보간법이 선정되어야 한다. 관련 논문을 검토한 결과, 측정 결과에 따른 2차원 횡단면 분포의 내용이 지배적이었고, 3차원 매핑 및 3차원 분석을 통한 수리학적 정보 획득에 관한 연구는 부족한 실정이였다. 특히 3차원 하천 수질 농도의 연구가 불충분했다. 그에 따라 저해상도 측정결과에서의 예측과 보간법에 대한 시각화를 통해 하천의 전체적인 수리·수질정보를 표기하였다. 각각의 보간법을 비교함으로써 하천 매핑에 있어 IDW, Natual Neighbor, Kriging 기법을 적용하여 시각화된 자료와 정량적 평가를 통해 하천매핑의 정밀성을 향상시켰다. 이를 통해 3차원화된 공간보간 자료를 이용한 하천합류부의 혼합양상을 해석하였다. 3차원 데이터를 활용하는 방법으로 측정 및 모니터링 기술의 중요한 데이터로 활용되며, 이러한 데이터는 유해물질 저감 기술 및 평가 예측 기술의 기초 데이터로 활용되고 있다. 유해화학물질 추정, 호수의 고위험 조류군 계층분석 등 다양한 수생건강 진단기술을 활용할 수 있다.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.477-486
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• 2008

Acrylic resin is widely used in dental practice. However, the residual monomer in acrylic resin could act as a negative biocompatability on human body. The aim of this study was to evaluate the amount of the monomer elution from polymerized orthodontic acrylic resin. Orthodontic acrylic resin was used in the study. The curing condition of the resin was controlled by temperature, pressure, aquatic and atmospheric environment. The duration and amount of monomer elution and timedependent plot was recorded by high performance liquid chromatography. The result showed that the only monomer eluted from the resin was methyl methacrylic acid. And the amount of the monomer elution has diminished considerably by time progress especially within 24 hours. Furthermore, elution of the residual monomer was significantly lower in group of pressure, moisture and elevated temperature than control (p<.05). According to this study, it was thought that the elution of residual monomer might be influenced by curing environment.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.85-92
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• 2006

To evaluate the primary production and nutrient uptake of macrophytes in Lake Paldang, this study investigate the vegetation areas of six dominant aquatic plants including Typha angustifolia, Zizania latifolia, Phragmites australis, Trapa japonica, Nelumbo nucifera and Savinia natans, and contents of carbon, nitrogen and phosphorus of each macrophyte. Total vegetation area of six dominant aquatic plants was 1.37 $km^2$. Among them, Typha angustifolia was the most wide-distributed species which occupied the 46.7% of total vegetation area. Littoral zone of South Han river had the largest vegetation area with 0.458 $km^2$, and North Han river, Kyungan river and confluence area in the order named. The results of the contents of carbon, nitrogen and phosphorus of macrophytes showed that the carbon contents of emergent macrophytes was higher than that of other life-forms. The nitrogen content of Salvinia natans, free-floating macrophyte was highest and that of Typha angustifolia, emergent macrophyte was lowest. The phosphorus content of Trapa japonica showed the highest content of phosphorus among six macrophytes and emergent macrophytes such as Zizania latifolia and Phragmites australis showed lower contents of phosphorus than other life-forms. The annual net primary production of macrophytes in Lake Paldang, 2004, was calculated as 758.4 ton C $yr^{-1}$ and the annual net nitrogen and phosphorus uptake of macrophyte was 16,921 kg $yr^{-1}$ and 1,841.0 kg P $yr^{-1}$ respectively. Comparing the total budget of organic carbon, nitrogen and phosphorus in Lake Paldang, the amount of primary production and nutrient uptake by macrophytes take a small portion in total budget implying macrophytes do not play an important role in budget of matters in river-type lake, Lake Paldang.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.21-31
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• 2006

The objectives of this study were to analyze trends of temporal water quality and trophic state in Andong and Imha reservoirs using chemical dataset during 1993 ${\sim}$ 2004, obtained from the Ministry of Environment, Korea. According to long-term limnological analyses, Suspended solids (SS) in Imha Reservoir were 2 ${\sim}$ 8 fold2 greater, than those in SS of Andong Reservoir, and the high solids increased total phosphorus (TP) and biological oxygen demand ($BOD_5$) and decreased the transparency, measured as Secchi depth (SD). Chlorophyll-a (CHL-a) increased little or decreased slightly in the both reservoirs during the high solids, resulting in reduced yields of CHL-a : TP ratios. The deviation analysis of Trophic State Index (TSI) in Imha Reservoir showed that about 70% of TSI (CHL-a)-TSI (SD) and TSI (CHL-a)-TSI(TP) values were less than zero and the lowest values were-60, indicating that influence of inorganic solids (or non-volatile solids) on phytoplankton growth was evident in Imha Reservoir and the impact was greater than that of Andong Reservoir. Inorganic solids in Imha Reservoir resulted in light limitation on phytoplankton growth and thus contributed variations in the relations among three parameters of trophic state index. Especially, seasonal data analysis of nutrients in both reservoirs showed that during the postmonsoon, mean TP concentration was Imha Reservoir greater in than that in Andong Reservoir. The higher TP concentrantion was mainly attributed to increases of inorganic solids from soil erosions and nonpoint source inputs within the watershed. The high inorganic turbidity in Imha Reservoir should be reduced for the conservation of water quality for, especially a tap water supply.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.1
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• pp.47-56
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• 1999

$^{15}N$-Isotope concentrations of groundwater from l4 wells with different land-use types in Kyonggi Province were measured to investigate the nitrate contamination sources. Water samples were collected monthly from January to December 1997 and analyzed for pH. PC, anions (fluoride, chloride, nitrate, sulfate, inorganic phosphate, and bicarbonate), and canons (calcium, magnesium, potassium, and sodium). For the analysis of the $^{15}N/^{14}N$ ratio as ${\delta}^{15}N$, $N_2$ samples were prepared through Kjeldahl-Rittenberg method and were analyzed using an isotope ratio mass spectrometer (VG Optima IRMS). Reproducibility of the method and precision of the IRMS were below 1.0‰ and 0.1‰, respectively. The ionic composition of each groundwater sample was only slightly different according to the land-use type. The nitrate concentrations of groundwater in cropland or livestock farming areas were higher than those in the residential area. The percentages of nitrate to total anions of groundwater samples from the livestock farming area were higher than those of other areas. The ${\delta}^{15}N$ values of ammonium sulfate, urea, groundwater sample in the non-contaminated area, and water from the animal manure septic tank were -2.7, 1.4, 5.5, and 27.2‰, respectively. Based on the ${\delta}^{15}N$ values, the sources of nitrate could be classified as originated from chemical fertilizers with ${\delta}^{15}N$ values below 5% and as from animal manure or municipal waste with ${\delta}^{15}N$ values over 10‰. In most cases, contamination sources investigated from ${\delta}^{15}N$ values of groundwater samples were correlated with the specific sources according to the land-use types. However, some ${\delta}^{15}N$ values did not matched the apparent land-use types, and there were seasonal variations of ${\delta}^{15}N$ values within the same well. These results suggest that the groundwater quality was affected by two or more contamination sources and the contribution of each source to the groundwater quality varied depending on the sampling season.

• Korean Journal of Heritage: History & Science
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• v.46 no.1
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• pp.290-317
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• 2013

The objectives of this study are to investigate the natural heritage and scientific value of various geosites on Udo Island, and to evaluate the sites as natural monuments and as world natural heritage properties. Udo Island includes a variety of geoheritage sites. Various land forms formed during the formation of the Someori Oreum formed by phreatomagmatic eruptions. The essential elements for the formation of Udo Island are the tuff cone, overflowing lava and overlying redeposited tuff sediments. Various coastal land forms are also present. About 6,000 years B.C., when sea-level rose close to its present level due to deglaciation since the Last Glacial Maximum, carbonate sediments have been formed and deposited in shallow marine environment surrounding Udo Island. In particular, the very shallow broad shelf between Udo Island and Jeju Island, less than 20 m in water depth, has provided perfect conditions for the formation of rhodoids. Significant amounts of rhodoids are now forming in this area. Occasional transport of these rhodoids by typhoons has produced unique beach deposits which are entirely composed of rhodoids. Additional features are the Hagosudong Beach with its white carbonate sands, the Geommeole Beach with its black tuffaceous sands and Tolkani Beach with its basalt cobbles and boulders. Near Hagosudong Beach, wind-blown sands in the past produced carbonate sand dunes. On the northern part of the island, special carbonate sediments are present, due to their formation by composite processes such as beach-forming process and transportation by typhoons. The development of several sea caves is another feature of Udo Island, formed by waves and typhoon erosion within tuffaceous sedimentary rocks. In particular, one sea cave found at a depth of 10 m is very special because it indicates past sea-level fluctuations. Shell mounds in Udo Island may well represent the mixed heritage feature on this island. The most valuable geoheritage sites investigated around Udo Isalnd are rhodoid depostis on beaches and in shallow seas, and Someori Oreum composed of volcanoclastic deposits and basalt lava. Beach and shallow marine sediments, composed only of rhodoids, appear to be very rare in the world. Also, the natural heritage value of the Someori Oreum is outstanding, together with other phreatomagmatic tuff cones such as Suwolbong, Songaksan and Yongmeori. Consequently, the rhodoid deposits and the Someori Oreum are worth being nominated for UNESCO World Natural Heritage status. The designation of Someori Oreum as a Natural Monument should be a prerequisite for this procedure.

• Korean Journal of Food Science and Technology
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• v.51 no.6
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• pp.531-536
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• 2019

In this study, the optimization of the manufacturing process for the oil-in-water emulsification of rice bran oil was performed by response surface methodology (RSM) using varying amounts of the emulsifier (0.05-0.25%), varying rotation speeds of the homomixer (4,000-8,000 rpm), and varying water to oil ratios (0.8-1.6%) as independent variables, and the emulsion stability index (ESI) as the dependent variable. The optimization conditions predicted by the RSM model were 0.2%g of the total amount of the rice bran oil emulsion, emulsified at the homomixer rotation speed of 6,700 rpm using a water to oil ratio of 1:3. The ESI of the rice bran oil emulsion prepared under the optimized conditions was 95.7%, which was similar to the predicted value of 94.4% obtained by the RSM model. The transmission stability and the backscattering values were found to agree with each other over time and the turbiscan stability index was less than 0.7, indicating that the aggregation and upper floatation were less while the dispersion stability was maintained.

• Tuberculosis and Respiratory Diseases
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• v.39 no.5
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• pp.392-399
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• 1992

Background: Despite dyspnea is a predominant complaint of patients with respiratory disease, the mechanisms contributing to the sensation of breathlessness are poorly understood. Traditionally, physicians have measured objective pulmonary function to assess severity of dyspnea. But it will be also useful to measure subjective dyspnea index because dyspnea probably depends on a complex interplay of mechanical, experimental, emotional and other factors. Method: We measured breathlessness at rest, after Methacholine challenge and then bronchodilator inhalation using a Visual Analogue Scale (VAS) and Borg Scale Dyspnea Index (BSDI) in stable asthmatic patients. Spirometry was performed concomittently. Results: There was no correlation between dyspnea index and FEV1. There was also no correlation between the change in dyspnea index and change in FEV1. The change in dyspnea index after methacholine and bronchodilator was greater in clinically mild asthmatic patients than clinically severe symptomatic group. Conclusion: In asthmatic patients, there was a wide variation in sensory response for any given FEV1, and the change in perception of dyspnea was greater in those with clinically mild symptoms. The measurement of dyspnea index may yield information complementary to that obtained by spirometry.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.10a
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• pp.234-236
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• 1979

인구의 도시집중과 고도산업사회 건설에 필연적으로 수반되는 도시하수 및 산업폐수등은 하천을 심각하게 오염시켜 하천수가 지니고 있는 자정능력 한계를 초과하고 있어 재생될수 없는 상태이므로 수자원의 보호가 요청된다. 이런 상황의 하천오염 증가 추세와 주요 오염원 및 오염물에 대하여 고찰하고 대책에 방향을 제시한다. 먼저 전국의 급수 현황과 장래를 보면 다음과 같다. 한편 수도권 한강수계를 오염시키는 주요 오염원인 폐수를 보면 주거지의 생활하수, 상업행위로 발생되는 폐수와 공장의 산업폐수로 대별할 수 있으며 수도권 한강에 유입 되는 지천 수질을 보면 다음과 같다. 위와 같은 상태의 총폐수량은 280만톤인데 비하여 청계, 중량하수처리장과 서부 북부 동부분뇨처리장의 일일 처리능력은 16.4%에 불과하다. 한편 서울지역 오염원구성비를 보면 다음과 같다. 이런 계속적인 오염물은 1977년 경우 갈수기에 80~100t/sec의 하천유량으로 희석되고 있어 자정능력 한계를 벗어나서 하류의 물은 혼탁하고 용존산소의 고갈현상을 초래하고 있다. 그러므로 도시 하천에서는 수류침체로 인한 하상퇴적을 방지하여 국소적 오염의 심화를 방지하며 유량을 증가 시켜야 한다. 수도권 한강 수계의 수질의 일부는 다음과 같다. 한편 생활수준의 향상과 더불어 수요가 급증되며 처리장의 효율과 하천수의 수질을 악화시키는 합성세제의 총생산량은 1971년에 21000톤이던 것이 1978년에는 약 50,000톤에 이르고 있으며 이중 55~60%가 서울지역에서 소모되는 것으로 추산되어 진다' 결과 한강수에서 검출되는 합성세제의 오염 현황을 보면 다음과 같이 이미 몇개 지점에서는 세계 보건기구의 허용량인 0.5ppm을 초과 하고 있는 실정이다. 또한 오염의 연쇄현상을 나타내는 중금속의 일종인 csduium의 검출 정도를 보면 다음과 같다. 이상의 하천오염에 따른 수중생태계의 변화는 물리적 화학적 생물학적 환경요인이 복합적으로 작용하는 세부적 기계에 대하여는 규명되지 않은 문제가 아직도 많으며 지표생물의 표현형은 중요한 가치를 부여하고 있다. 식물성 plankton의 우점종의 출현 빈도에 따른 수질계급을 보면 뚝섬지역 BOD 3.3~5.3 빈부수성 $~\alpha$ 중부수성, 보광동 BOD 6.0~10.3중부수성, 제 2한강교 BOD10~28 $\alpha$ 강부수성, 난지도 BOD29 $\beta$ 강부수성 등이며 이와 상이한 결과도 보여주고 있다. 이상으로 볼 때 1) 가정하수의 질을 높이기 위하여 분뇨정화조 의 효율증대 2) 산업폐수의 공정별 폐수량의 조절 및 폐수성 상에 따른 총량규제에 대비한 효율증대 3) 하천의 오염부하와 자정능력 최대한 부여 4) 폐수처리를 위한 미생물제개발 및 오염지표 종 연구와 오염내성 생물의 연구등이 종합적 으로 수행되어야 한다. 5) 이상의 모든 조사와 연구결과를 객관적으로 표기할 수 있도록 하천의 이정표가 정해져야 하겠다.