• Journal of Power System Engineering
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• v.3 no.1
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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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• 1999.12a
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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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• v.9 no.2
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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.

• (The)Study of the Eastern Classic
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• no.73
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• pp.119-151
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• 2018

This paper is a study of the historical significance of The water and land ceremony performed by Bongeunsa temple in the Joseon Dynasty. The Bongeunsa temple was originally a hermitage named Geungseongam, which was located in the Hakdang-dong, Gwangju County, Gyeonggi Province. After that, Geungseongam was named as Geungseongsa temple. Geungseongsa temple was left in that position and acted as the Temples belonging to Royal Tombs(陵寢寺, TRT) of the King Sungjong, later the name of the temple was changed to Bongeunsa Temple. As a result of movement of the royal tomb of the Joongjong(靖陵) next to the royal tomb of Sungjong, the Bongeunsa was also used as a TRT of the Seonjeongneung royal tomb. After that, the grandson of the King Joongjong, crown prince Soonhoe early passed away, Buddhist shrine (願堂) was set in Bongeunsa temple. Bongeunsa temple remained as a royal prayer place, serving as a Buddhist shrine for crown prince Soonhoe and serving as a Jopo temples for Seonjeongneung royal tomb until the end of the Joseon Dynasty. From the time when it was called Geungseongam to the time after when it was renamed as Bongeunsa Temple, this temple performed The water and land ceremony. But the characters changed little by little. From the King Sejo to King Sungjong, The water and land ceremony characterized Consolation ceremony for the spirit of the dead for prince Gwangpyeong, King Sejong, Queen Soehan and served as the Buddhist memorial praying for the well being of the royal family and people. From the time of the King Yonsan to the time of King Myeongjong, The water and land ceremony had strong characters for Consolation ceremony for the spirit of the dead for King. In the late Joseon Dynasty, Bongeunsa Temple served as the royal party of The water and land ceremony. On the other hand, after the Manchu war of 1636, Bongeunsa Temple also served as the national water and land ceremony for the victims who were killed in the mountains of Namhan. In the Joseon dynasty, The water and land ceremony performed by Bongeunsa Temple was strongly directed for Consolation ceremony for the spirit of the dead for royal family members, and Bongeunsa Temple was maintained as a royal prayer throughout the Joseon Dynasty.

• Membrane Journal
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• v.8 no.4
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• pp.203-209
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• 1998

The cutting oil emulsion microfiltration was carried out on dead-end call and crossflow systems equipped with 0.22 $\mu$m GVHP Millipore and 0.2 m stainless steel Mott microfiltration membranes, respectivdy. The oil drop size in the emulsion was varied from 0.07 to 0.22 $\mu$m. Cake filtration(CFM) and standard pore blocking models(SPBM) were applied to predict the permeation flux. The permeation fluxes of 0.01 vol% oil emulsion followed CFM for dead-end system very well under the condition of 400 rpm and below 100 kPa. The SPBM was, however, suitable for the permeation flux at 400 rpm and above 150 kPa. The oil layer on the membrane surface was destroyed and reproduced repeatedly as operating pressure was suddenly changed from 60 to 200 kPa, and then returned to 60 kPa. Also, we estimated the critical entry pressure(CEP) which is changed from CFM to SPBM, and CEP for dead-end system was around 100 kPa. The CEP increased from around 100 to 150 kPa for the crossflow system as the oil concentration increased from 0.01 to 0.03 vol% when Reynolds number was 7080.

• Journal of fish pathology
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• v.34 no.2
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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.

• Journal of the korean academy of Pediatric Dentistry
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• v.51 no.2
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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.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.4
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• pp.223-231
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• 2014

In order to prevent the spread of non-indigenous aquatic species through the ballast water in commercial ships, International Maritime Organization (IMO) adopted in 2004 the International Convention for Control and Management of Ship's Ballast Water and Sediments. The Convention mandates treatment of ballast water for most transoceanic voyages and its confirmation of treatment is made with plankton live/dead assay. Fluorescein diacetate assay (FDA), which produces bright green light for live phytoplankton, has been a de facto standard method to determine the survival of marine plankton, but its staining efficacy has been in dispute. In the present study, we examined the limitation of FDA, and compared its efficacy with Neutral red (NR) staining, another promising assay and widely used especially for zooplankton mortality. For all phytoplankton species studied in the present study, except Ditylum brightwellii, the staining efficiency was <50% with FDA. The green FDA fluorescence interfered with phytoplankton autofluorescence in most samples. In contrast, NR assay stained over 90% of both phytoplankton and zooplankton species tested in this study. FDA assay also showed that green FDA fluorescence rapidly faded when phytoplankton cells were exposed to microscope light. Both FDA and NR assay were negative on formalin-killed individuals of both phytoplankton and zooplankton species. Our results suggest that NR assay is more effective for determining the survival of marine plankton and can be applied to test the efficacy of ballast water treatment.

• Ocean and Polar Research
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• v.42 no.3
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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.

• Journal of Korean Society of Water and Wastewater
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• v.9 no.3
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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.