• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1107-1112
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• 2006

The purpose of this study is a heat transfer coefficient test of evaporator tube in shell and tube heat exchanger by shapes, using R-404A. The experimental apparatus is designed to simulate the real heat transfer rate in one shell and tube heat exchanger. The test section is formed four type tubes that are Inner ridged tube, Corrugated tube, Turbo-C tube, Inner fin tube and shell type is formed by electrical heater. All tests were performed at a fixed refrigerant evaporator temperature at $1.5^{\circ}C,\;-3^{\circ}C$ and with mass fluxes of 29, 25 kg/hr. Heat transfer rate is calculated a enthalpy difference in test section. In experiment, heat transfer coefficient measured one by one and electrical heaters are supplemented by evaporator.

• Journal of Aquaculture
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• v.13 no.2
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• pp.119-128
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• 2000

Exposure to air and increased temperature induced successful spawning in Mytilus edulis, M. coruscus Crassostrea gigas and Pinctata fucata martensii. Developmental durations required for an egg to attain D-shaped larva and the D-shaped larva to reach pediveliger stage were estimated in these bivalves. Size of fertilized eggs was the largest (70.3 ${\mu}m$) in M. coruscus and the smallest (45.3 ${\mu}m$) in P. fucata martensii. At 17$^{\circ}C$, M. edulis and M. coruscus attained D-shaped larval stage within 48 hours after fertilization but those of C. gigas and B. fucata martensiii within 24 and 22 hours at 21 and 26$^{\circ}C$, respectively. The development duration required for a D-shaped larva to attain pediveliger stage was the longest (27 days) in M. coruscus and ranged between 20 and 22 days for the others. The shell length of the pediveliger was the longest (274.9 ${\mu}m$) in C. gigas and smallest (190.9 ${\mu}m$) in P. fucata martensii Length and height of larval shell was highly correlated with each other in all the 4 species. The shell height of C. gigas was more than the shell length beyond the size of 100 ${\mu}m$ shell length. However, shell length of the others was always longer than shell height at the larval stage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.3_4
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• pp.92-98
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• 1971

With Saxidomus Purpuratus which were sampled near Yungdo, in the harbor of Pusan during the period from September 1967 to October 1968, the author investigated the maturity against seasonal change of water temperature; and shell length, height and width against live weight, respectively, and the reciprocal correlations of shell length, height and width, as well. The maturity, concerned deeply with tile developing procedure of gonad, is dependent on the change in water temperature. The value of maturity becomes higher from March to May, but in August with high temperature the value decreases temporarily. During the main spawning season from the late August to the middle of October, the value shows the peak throughout a year. After the period, it has decreased until January when the water temperature is below $10^{\circ}C$ The equations of shell length against live weight for male($W=0.4749L^{2.62307}$)and for female ($W=0.3438L^{2.77993}$) shell height against live weight ($W=0.3221L^{3.06661}$), and shell width against live weight ($W=3.5868L^{2.46646}$), show non-straight lines respectively. On the other hand, th: equations of shell length against shell height Y=0.818x+0.292 (r=0.958), shell length against shell width Y=0.520x+0.200 (r=0.799) and shell height against shell width Y=0.499x+0.516 (r=0.773) show straight lines, respectively.

• The Korean Journal of Malacology
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• v.23 no.1
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• pp.17-23
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• 2007

Samples of Potamocorbula ustulata ustulata were collected monthly from October 2004 to November 2005 in the Jujin estuary of Gochang, Chollabuk-do, west coast of Korean peninsula. Age of P. ustulata ustulata was determined by the rings on the shell. The relationship between the shell length and the ring diameter in each ring group was expressed as a regression line. Therefore, there is a correspondence in each ring formation. Based on the monthly variation of the marginal index (MI') of the shell, it is assumed that the ring of this species was formed once a year during October to December. The relationship between the shell length (SL) and the shell height (SH; mm) was highly correlated with shell height as the following equation: SH = 0.6438 SL + 0.5642 ($r^2\;=\;0.978$). The shell length (SL) - shell width (SW) relation was also expressed by the following equation: SW = 0.4352 SL - 0.5675 ($r^2\;=\;0.957$). Shell length (SL; mm) and the total weight (TW; g) followed: $TW\;=\;6.999\;{\times}\;10^{-5}\;SL^{3.2542}(r^2\;=\;0.975)$. Growth curves for the shell length and the total weight fitted to the von Bertalanffy's growth curve were expressed respectively as: $$SL_t=30.77[1-e^{-0.4572(t+0.7371)}],\;TW_t=4.87[1-e^{-0.4572(t+0.7371)}]^{3.2542}.$$

• Journal of Powder Materials
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• v.17 no.4
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• pp.295-301
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• 2010

Multi shell graphite coated Ag nano particles with core/shell structure were successfully synthesized by pulsed wire evaporation (PWE) method. Ar and $CH_4$ (10 vol.%) gases were mixed in chamber, which played a role of carrier gas and reaction gas, respectively. Graphite layers on the surface of silver nano particles were coated indiscretely. However, the graphite layers are detached, when the particles are heated up to $250^{\circ}C$ in the air atmosphere. In contrast, the graphite coated layer was stable under Ar and $N_2$ atmosphere, though the core/shell structured particles were heated up to $800^{\circ}C$. The presence of graphite coated layer prevent agglomeration of nanoparticles during heat treatment. The dispersion stability of the carbon coated Ag nanoparticles was higher than those of pure Ag nanoparticles.

• Journal of Ocean Engineering and Technology
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• v.25 no.5
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• pp.40-46
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• 2011

This study carried out a series of experiments involving impact tests (Drop weight type & Charpy type with a standard specimen and newly designed I-type specimen), hardness tests, and fracture surface observations of French-made roll shell steel (F), abnormal roll shell steel (M), reheated roll shell steel (R), and S25C steel under heat treatment conditions ($570^{\circ}C$) to analyze the cause and prevent the roll shell steel's brittle fracture and its damage.

• Transactions of Materials Processing
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• v.22 no.6
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• pp.317-322
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• 2013

A radio frequency(R/F) switch connector is widely used in wireless devices such as mobile phone and navigator to check defects of the circuit board of product. The R/F switch connector shell plays a role in protecting the switch connector. Previously, this part was machined using a turning, which is time-consuming and has poor material utilization. Furthermore, the workpiece material of brass containing lead that has excellent machinability has environmentally regulated during recent years. The purpose of the current study was to develop the connector shell by forming through progressive dies including embossing, burring and forging process in order to achieve higher productivity and dimensional accuracy without tool failure. To accomplish this objective, a strip layout was designed and finite element (FE) analysis was performed for each step in the process. Try-out for the connector shell was conducted using progressive die design based on FE-analysis results. Dimensional accuracy of developed part was investigated by scanning electron microscopy. The result of the investigation for the dimensions of the formed connector shell showed that the required dimensional accuracy was satisfied. Moreover, productivity using the progressive die increased four times compared to previous machining process.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.1-6
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• 2016

In this year, Koreans have a shortage in agricultural and drinking water due to severe algal blooms generated in major lakes. Waste oyster shells were obtained from temporary storage near the workplace at which oysters were separated from their shells. Heating ($1000^{\circ}C$ for 1 h in air) was employed to convert raw oyster shell powders into calcium oxide powders that reacted efficiently with phosphorus and nitrogen to remove algal blooms from eutrophicated wastewater. As the dispersed amount of heated oyster shell powders was increased, water clarity and visual light penetration were improved. Coagulation, precipitation and carbonation process of the heated oyster shell powders in a water purifier facilitated removal of eutrophication nutrient such as phosphorus and nitrogen, which is both beneficial and economically viable. $CO_2$ implantation by carbonation treatment not only produced thermodynamically stable CaO in oyster shells to derive precipitated calcium carbonate (PCC) but also accelerated algal removal by activation of coagulation and precipitation process. The use of oyster shell powders led to a mean reduction of 97% in total phosphate (T-P), a mean reduction of 91% in total nitrogen (T-N) and a maximum reduction of 51% in chemical oxygen demand (COD), compared with the total pollutant load of raw algal solution. Remarkable water quality improvement of algal removal by heated oyster shell powders and PCC carbonation treatment will allow utilization as water resources to agricultural or industrial use.

• The Korean Journal of Malacology
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• v.21 no.1
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• pp.57-64
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• 2005

Samples of Corbicula japonica Prime of Jujin estuary in Gochang were collected from July 2000 to September 2001. Age of C. japonica was determined from the rings on the shell. The relationship between shell length and ring radius in each ring group was expressed as a regression line. Therefore, there is a correspondence in each ring formation. Based on the monthly variation of the marginal index (MI') of the shell, it is assumed that the ring of this species was formed once a year during the period of February and March. The relationship between shell length (SL; mm) and total weight (TW; g) was expressed by the following equation: TW = 1.0942 ${\times}10^{-4}SL^{3.3217}$ ($r^2$ = 0.9905). Shell length (SL) and shell height (SH; mm) was highly correlated with shell height as the following equation: SH = 0.9174 SL - 0.9935 ($r^2$ = 0.9885). The shell length (SL) - shell width (SW) relation was also expressed by the following equation; SW = 0.5925 SL - 1.1706 ($r^2$ = 0.9726). Growth curves for shell length and total weight fitted to the von Bertalanffy's growth curve were expressed as: $$SL_t = 46.4861[1-e^{-0.3383(t+0.0958)}]$$, $$TW_t = 34.54[1-e^{-0.3383(t+0.0958)}]^3.3217$$.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.93-93
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• 2011

Nanostructures consisting of $TiO_2$ particles as a core and carbon as a shell ($TiO_2$@C) were prepared by heat treatment of $TiO_2$ nanoparticles at high temperature in a methane atmosphere. X-ray diffraction and transmission electron microscopy showed that a carbon shell layer was formed well. These structures were used as supports for platinum nanoparticles and the hybrid particles exhibit improved catalytic activity and stability toward ORR compared to Pt on a carbon black (Vulcan XC-72R). It is likely that enhanced catalytic properties of the Pt on $TiO_2$@C could be due to the stability of the core-shell support in comparison with carbon black support.