• 동력기계공학회지
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• 제3권1호
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• pp.16-22
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• 1999

The purpose of this study is to prevent the stick, scuffing, scratch between piston and cylinder, is to contribute the piston design such as piston profile, clearance by calculating reaction force by over-lap of piston skirt, as measuring the temperature distributions of cylinder wall. The experiment has been peformed to obtain data during actual engine operation. Temperature gradient in peripheral and axial distributions of cylinder wall according to torque and speed of engine were measured by use of an 800cc class gasoline engine. The results obtained are summarized as follows ; 1) The temperature of cylinder wall at TDC was about $50{\sim}75^{\circ}C$ higher than temperature of cooling water. 2) The rear side temperature of top dead center was $141^{\circ}C$(1/4 load) in axial distribution, whereas the rear side of midway position temperature was $98^{\circ}C$. 3) The temperature of cylinder wall increased in according to rising temperature of cooling water. 4) The thrust side temperature of cylinder wall was about $15^{\circ}C$ in all load test. 5) The rear side temperature of top dead center was $159^{\circ}C$ (1/2 load) in peripheral distribution, it was about $39^{\circ}C$ higher than thrust side temperature.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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• pp.46-51
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• 1999

This paper describes the control charcteristics of thermal/flow systems. In thermal/flow systems, the transport lag plays as a dead time causing a deterioration of the controllability. Besides this, such many parameters including the temperature, pressure, and flow rate affect the system response that a control scheme which can deal with multi-input is required. Particularly in a refrigerant compressor test facility, the evaporator and condenser interact each other so that the change in the evaporator pressure cause the condenser pressure to change or vice versa. Therefore, to control the evaporator pressure, not only the cooling water flow rate in the evaporator but also the coolant flow rate in the condenser is considered. Meanwhile, the conventional PID controllers, which is suitable for a single input system, shows a large overshoot for a disturbance input. In this work, the predictive control scheme is introduced and its applicability is discussed for thermal/flow systems.

• Journal of the Korean Wood Science and Technology
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• 제9권2호
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• pp.31-35
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• 1981

This study was carried out to investigate the properties of hardboard made from fire killed larch tree and also effects of standing period after killed by fire. The results are as follows; 1. There were no effects on hardboard properties among the standing period differences after killed by fire within about 2 years. 2. Specific gravities, moisture contents, water absorptions of the boards from dead trees have no differences compared with those of sound wood. 3. Bending strengths of the boards from dead trees we re decreased in the range of 24-28% of the boards from sound wood.

• 동양고전연구
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• 제73호
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• pp.119-151
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• 2018

본 논문은 봉은사의 기원과 조선시대 봉은사에서 설행된 수륙재의 역사적 의미를 고찰한 연구이다. 봉은사는 원래 경기도 광주군 학당동(오늘날의 선릉 능역 내)에 위치했던 견성암이라는 이름의 암자였다. 견성암의 창건시기는 불분명하나, 조선전기에 광평대군의 재암(齋庵)으로 지정되면서 크게 중창되었다. 광평대군부인 신씨는 남편의 무덤 근처에 있던 견성암에 70결의 대토지와 1000여 구의 노비를 시주하여 대찰(大刹)로 중창하였다. 이후 견성암은 견성사라는 이름으로 불리게 되었다. 1450년 성종의 능(선릉(宣陵))이 광평대군묘와 견성사가 위치한 곳에 들어서면서 광평대군묘는 인근의 대모산 자락으로 이장되었다. 하지만 견성사는 그대로 남아 성종의 능침사로 역할하게 되었고 절 이름은 봉은사로 개칭되었다. 1562년 중종의 능(정릉(靖陵))이 선릉 부근으로 이장되면서 봉은사는 선 정릉의 능침사를 겸하게 되었다. 1563년 순회세자가 요절한 뒤에는 세자의 원당이 봉은사 내에 마련되었다. 견성암 때부터 봉은사로 개칭된 이후까지 이 절에서는 수륙재가 계속 설행되었다. 하지만 수륙재의 성격은 시기별로 조금씩 달라졌다. 세조대부터 성종대까지 견성암과 견성사에서 설행된 수륙재는 광평대군과 세종, 소헌왕후의 명복을 비는 천도재의 성격과 왕실 및 사부대중의 안녕을 기원하는 대중법회의 성격을 동시에 지니고 있었다. 이후 연산군~명종대에 이르러 선정릉의 능침사로 역할할 당시 봉은사에서 설행된 수륙재는 왕의 천도재 성격이 강했다. 조선후기에도 봉은사는 순회세자의 원당으로 역할하였기 때문에 봉은사는 왕실 수륙재도량으로 계속 유지되었던 것으로 보인다. 또한 병자호란 이후 봉은사는 남한산성에서 전사한 희생자들을 위무하는 국행 수륙재도량으로도 역할하였다.

• 멤브레인
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• 제8권4호
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• pp.203-209
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• 1998

에멀젼형 절삭유(Caltex, Trusol) 수용액을 공칭 세공크기가 0.22 $\mu$m 인 Millipore사의 GVHP 막과 0.2$\mu$m인 SUS 관형막(Mott 사)이 설치된 dead-end 및 십자형흐름 정밀여과 시스템으로 각각 분리하였다. 오일입자의 분포는 0.07 내지 0.22$\mu$m의 분포이었다. 투과유속을 예측하기 위하여 cake 여과모델 (CFM)과 standard pore blocking 모델(SPBM)을 적용하였다. Dead-end 시스템에서 0.01 vol% 절삭유 수용액을 400 rpm으로 교반시켜 투과시킬 경우, 100 kPa 이하에서는 CFM 이 투과유곡을 잘 나타내었으나, 150 kPa 이상에서는 SPBM을 적용할 수 있었다. 운전압력을 60에서 200 kPa로 갑자기 증가시키면 분리막 표면에 형성된 오일층이 파괴되고, 다시 60 kPa로 감소시킬 때 반복하여 오일층이 형성됨을 알 수 있었다. 투과기구가 CFM에서 SPBM 으로 전환되는 이른바 임계압력을 추정하였으며, dead-end system에서는 약 100 kPa이었다. Reynolds 수가 7080인 십자형흐름 시스템에서 농도를 0.01에서 0.03 vol%로 증가시키면 입계압력이 약 100에서 150 kPa로 증가하였다.

• 한국어병학회지
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• 제34권2호
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• pp.255-259
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• 2021

This is the first report describing acute mass mortality occurred in juvenile olive flounder (Paralichthys olivaceus) caused by gas bubble disease (GBD). A total of 610 fish (average weight = 35 g), which were more than half of the fish acclimated at 17℃ in an aquarium, were killed within two days of acclimation. The dead and moribund fish showed excessively opened opercula and mouths, and occasionally, severe exophthalmia. Through microscopic observation, numerous gas emboli were found in the gills of the dead and live fish, while the fish were not infected with any microbial pathogens. The dissolved oxygen (DO) saturation level of the rearing water and seawater nearby the facility reached 145% and 286%, respectively, whereas other water quality parameters (such as salinity, pH, and chemical oxygen demand) were normal. The extreme saturation rate of seawater in the shore nearby seemed to be due to an enormous algal bloom that occurred there. Through molecular identification based on 18S rDNA sequences, the most dominant algal species was most closely related to Ulva californica (99.87% sequence identity) followed by U. prolifera, U. linza, and U. curvata (99.81%). Therefore, it can be concluded that supersaturated seawater due to mass algal bloom caused gas bubble disease in the olive flounder, leading to mass mortality. After technical adjustment, such as increased aeration, lowered water circulation rate, and inlet water filtration using micro-pore carbon filters, the DO level became normal, no further mortality occurred and the status of the fish was stabilized.

• 대한소아치과학회지
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• 제51권2호
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• pp.149-164
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• 2024

This study compared the solubility, water absorption, dimensional stability, release of various ions (hydroxyl, calcium, sulfur, strontium, and silicon), and cytotoxicity of light-cured resin-modified pulp-capping materials. Resin-modified calcium hydroxide (Ultra-blend^TM plus, UBP), light-cured resin-modified calcium silicate (TheraCal LC^TM, TLC), and dual-cure resin-modified calcium silicate (TheraCal PT^TM, TPT) were used. Each material was polymerized; solubility, 24-hour water absorption, and 30- day dimensional stability experiments were conducted to test its physical properties. Solubility was assessed according to the ISO 6876 standard, and 24 hours of water absorption, 30 days of dimensional stability were assessed by referring to the previous protocol respectively. Eluates at 3 and 24 hours and on 7, 14, and 28 days were analyzed according to the ISO 10993-12 standard. And the pH, Ion-releasing ability, cell proliferation rate, and cell viability were assessed using the eluates to evaluate biochemical characteristics. pH was measured with a pH meter and Ion-releasing ability was assessed using inductively coupled plasma atomic emission spectrometry (ICP-AES). Cell proliferation rate and cell viability were assessed using human dental pulp cells (hDPCs). The former was assessed by an absorbance assay using the CCK-8 solution, and the latter was assessed by Live and Dead staining. TPT exhibited lower solubility and water absorption than TLC. UBP and TPT demonstrated higher stability than TLC. The release of sulfur, strontium, calcium, and hydroxyl ions was higher for TLC and TPT than for UBP. The 28-day release of hydroxyl and silicon ions was similar for TLC and TPT. TLC alone exhibited a lower cell proliferation rate compared to the control group at a dilution ratio of 1 : 2 in cell proliferation and dead cells from Live and Dead assay evaluation. Thus, when using light-cure resin-modified pulp-capping materials, calcium silicate-based materials can be considered alternatives to calcium hydroxide-based materials. Moreover, when comparing physical and biochemical properties, TPT could be prioritized over TLC as the first choice.

• 한국해양학회지:바다
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• 제19권4호
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• pp.223-231
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• 2014

선박평형수를 통한 외래종 확산을 방지하기 위해 국제해사기구(IMO)에서는 2004년 선박평형수관리협약을 채택하였다. 이 협약에 따르면 앞으로 대부분의 선박들은 선박평형수 처리시스템을 통해서 해양 생물을 사멸 또는 제거시킨 후 배출해야 하며, 이는 플랑크톤의 생사판별방법을 통하여 이루어진다. 본 연구에서는 국제적으로 선박평형수 처리후 생사판별법으로 널리 사용되고 있는 fluorescein diacetate assay (FDA) 염색방법의 제한성과 이의 대안으로 Neutral red (NR) 염색방법사용 가능성을 살펴보고자 하였다. FDA 염색법은 대부분의 플랑크톤 염색에 되어서 현재 가장 널리 사용되는 방법임에도 불구하고 본 연구에서는 Ditylum brightwellii 을 제외한 모든 식물플랑크톤 대해서 낮은 염색 효율(전체 평균 염색 효율 <50%)을 보였으며, 식물플랑크톤이 갖는 고유한 형광(적색)에 간섭을 많이 받는 것으로 나타났다. 또한 FDA는 형광파장에 노출된 후 빠르게 색이 바래지는 경향도 관찰되었다. 반면에 NR은 조사된 모든 동 식물플랑크톤 개체수에 대해서 90% 이상의 높은 염색 효율을 보였다. 두 염색법 모두 포르말린을 이용해서 사멸시킨 동 식물플랑크톤에 대해서는 염색이 되지 않았다. 본 연구결과를 통해서 NR 염색법을 이용한 동 식물플랑크톤 생사판별은 매우 효율적이라고 판단된다.

• Ocean and Polar Research
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• 제42권3호
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• pp.233-247
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• 2020

This study was carried out at 5 sites 11 times over two years to identify the variation of benthic environments and benthic polychaetous community and analyze the benthic healthiness in Dangdong Bay, a small semi-enclosed inner bay of Jinhae Bay. The temperature of bottom water showed the typical temporal fluctuation of a temperate zone and was in the range of 5.94 ~ 23.94℃. The salinity did not change significantly during the study period and was in the range of 32.93 ~ 35.72 psu. The concentration of dissolved oxygen of bottom water fluctuated a great deal and was in the range of 0.31 ~ 10.20 mg/L. The lowest DO value was recorded in July 2015, as 0.31±0.04 mg/L corresponding to the hypoxic water mass. The hypoxic water mass was formed continuously at some sites also in July and August 2016. The mean grain size was in the range of 7.57 ~ 9.81Ø and the average was 8.89±0.20Ø. The surface sediments were mainly composed of fine sediment (mud) above 85%. The mean of TOC was 3.09±0.22% and LOI was 13.30±0.47%, showing very high levels in Korean coastal waters. The concentration of AVS was in the range of 0.33 ~ 1.28 mgS/g-dry. The high values of organic contents and AVS indicated that there had been the serious organic enrichment in Dangdong Bay. The number of species and the density of the benthic polychaetous community in Dangdong Bay were in the range of 2 ~ 38 species and 2 ~ 2,185 ind./㎡ during the study period. The number of species and density were highly sustained in winter and spring, and then decreased gradually with the formation of a hypoxic water mass in summer, and the lowest number of species and density were recorded in autumn. In September and November 2015, the dead zone expanded to almost the whole study area. Dominant polychaetous species were Capitella capitata, Lumbrineris longifolia, Paraprionospio patiens and Sigambra tentaculata, each known as opportunistic species and potential organic pollutant indicator species. In particular, Paraprionospio patiens showed a very high population density of 2,019 ind./㎡ in December 2016. Polychaetous communities at each sampling time were classified into 4 temporal groups according to dominant species in each period by cluster analysis and nMDS. 'Period Group AI' was formed in winter and spring of 2015, dominated by Capitella capitata, 'Period AII' in summer dominated by Lumbrineris longifolia, 'Period B' in autumn with no fauna in the dead zone, and particularly 'Period C' in winter of 2016 dominated by Paraprionospio patiens. As a result of analysis of benthic healthiness, the study area was estimated to be in a Fair~Very Poor condition by AMBI and in a Poor~Very Poor condition by BPI during the study period. Both AMBI and BPI showed that the study area was in a Very Poor condition in September and November 2015, and when the dead zone occurred. In Dongdong Bay, the fact that the formation of a hypoxic water mass occurred in summer and a dead zone in autumn were confirmed. In addition, the dominance of opportunistic and organic pollutant indicator species was also observed clearly. The benthic healthiness indexes such as AMBI and BPI showed that organic enrichment was serious in Dangdong Bay.

• 상하수도학회지
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• 제9권3호
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• pp.78-87
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• 1995

A study on the fouling control by periodical ozone-scrubbing was conducted in a membrane filtration process for drinking water treatment. Hydrophilic hollow fiber polyethylene membrane with pore size of $0.1{\mu}m$ and its surface area of $0.42m^2$ was used. Dead-End filtration method was selected to obtain high efficiency of energy. Laboratory prepared synthetic raw water with kaolin was used and the membranes were scrubbed by ozone once in an hour and once in two hours. When the duration of ozone scrubbing was increased from 10 seconds to 20 seconds, the rate of membrane fouling was significantly decreased. Although the frequency of ozone-scrubbing was reduced from once in an hour to once in two hours. the effect of fouling control was unchanged. However, ozone-scrubbing was not effective after a membrane was fouled and washed with detergent for reuse. Among several possible working effects of ozone, bactericidal effect was confirmed to be the primary reason of fouling control.