• Food Science and Preservation
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• v.19 no.5
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• pp.633-638
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• 2012

The aim of this study was to investigate the growth of aerobic bacteria in fresh-cut salad during short-term temperature abuse ($4{\sim}30^{\circ}C$temperature for 1, 2, and 3 h) for 72 h and to develop predictive models for the growth of total viable cells (TVC) based on Predictive food microbiology (PFM). The tool that was used, Pathogen Modeling program (PMP 7.0), predicts the growth of Aeromonas hydrophila (broth Culture, aerobic) at pH 5.6, NaCl 2.5%, and sodium nitrite 150 ppm for 72 h. Linear models through linear regression analysis; DMFit program were created based on the results obtained at 5, 10, 20, and $30^{\circ}C$ for 72 h ($r^2$ >0.9). Secondary models for the growth rate and lag time, as a function of storage temperature, were developed using the polynomial model. The initial contamination level of fresh-cut salad was 5.6 log CFU/mL of TVC during 72 h storage, and the growth rate of TVC was shown to be 0.020~1.083 CFU/mL/h ($r^2$ >0.9). Also, the growth tendency of TVC was similar to that of PMP (grow rate: 0.017~0.235 CFU/mL/h; $r^2=0.994{\sim}1.000$). The predicted shelf life with PMP was 24.1~626.5 h, and the estimated shelf life of the fresh-cut salads with short-term temperature abuse was 15.6~31.1 h. The predicted shelf life was more than two times the observed one. This result indicates a 'fail safe' model. It can be taken to a ludicrous extreme by adopting a model that always predicts that a pathogenic microorganism will grow even under conditions so strict as to be actually impossible.

• Clean Technology
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• v.26 no.2
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• pp.137-144
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• 2020

Metal-impregnated activated carbons were prepared via ultrasonic-assisted impregnation method for regeneration and low ammonia concentration. Magnesium and copper were selected as metals, while chloride (Cl^-) and nitrate (NO₃^-) precursors were used to impregnate the surface of activated carbon. The physical and chemical properties of the prepared adsorbents were characterized by TGA, BET, and NH₃-TPD. The ammonia breakthrough test was carried out using a fixed bed and flowing ammonia gas (1000 mg L^-1 NH₃, balanced N₂) at 100 mL min^-1, under conditions of temperature swing adsorption (TSA) and pressure swing adsorption (PSA, 0.3, 0.5, 0.7, 0.9 Mpa). The adsorption and desorption performance of ammonia were in the order of AC-Mg(Cl) > AC-Cu(Cl) > AC-Mg(N) > AC-Cu(N) > AC through NH₃-TPD and TSA and PSA processes. AC-Mg(Cl) using MgCl₂ showed the average adsorption amount of 2.138 mmol/g at TSA process. Also, AC-Mg(Cl) showed the highest initial adsorption amount of 3.848 mmol/g at PSA 0.9 Mpa. When metal impregnated the surface of the activated carbon, it was confirmed that not only physical adsorption, but also chemical adsorption increased, making enhancement in adsorption and desorption performances possible. Also, the prepared adsorbents showed stable adsorption and desorption performances despite repeated processes, confirming their applicability in the TSA and PSA processes.

• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1158-1164
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• 1998

Aluminium sulfate solution was prepared by sulfuric acid treatment from gibbsite. Aluminium sulfate hydrate [$Al_2(SO_4)_3$ · $nH_2O$] was precipitated from aluminium sulfate solution by adding it into ethylalcohol. From XRD analysis as-prepared $Al_2(SO_4)_3$ · $nH_2O$ was confirmed to have mixed-crystalization water(n=18, 16, 12, 6). The average water of crystalization calculated from thermogravimetry(TG) was 14.7. Aluminium sulfate hydrate [$Al_2(SO_4)_3$ · $nH_2O$] was thermally decomposed and converted to $Al_2(SO_4)_3$ at $800^{\circ}C$, $\gamma-Al_2O_3$ at $900-1000^{\circ}C$, and $\alpha-Al_2O_3$ at $1200^{\circ}C$. Ni-doped $\gamma-Al_2O_3$, was synthesized from the slurry of as-prepared $\gamma-Al_2O_3$, with the ratio of [Ni]/[Al]=0.5. The reaction conditions of synthesis were determined as initial pH 9.0 and temperature $80^{\circ}C$ The basicity(pH) of slurry was controlled by using urea and $NH_4OH$ solution. Urea was also used for deposition-precipitation. For determining termination of reaction, the data acquisition was performed by oxidation reduction potential(ORP), conductivity and pH value in the process of reaction. Termination of the reaction was decided by observing the reaction steps and rapid decrease in conductivity. On the other hand, BET(Brunauer, Emmett and Teller) and thermal diffusity of Ni- doped $\gamma-Al_2O_3$, with various content of Ni were measured and compared. Thermal stability of Ni- doped $\gamma-Al_2O_3$ at $1250^{\circ}C$ was confirmed from BET and XRD analysis. The surface state of Ni-doped $\gamma-Al_2O_3$ was investigated by X-ray photoelectron spectroscopy(XPS). The binding energy at $Ni2P_{3/2}$ increased with increasing the formation of $NiAl_2O_4$ phase.

• Journal of the Korean association of regional geographers
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• v.5 no.2
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• pp.47-117
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• 1999

This study concern with the pattern of Pusan Station shopping district within Pusan City, Korea, one of the special functioned shopping district within Pusan City. This paper will serve as a part of series studies which attempt to clarify the internal structure of Pusan as a whole. Part(II) of this study deals with the functions including living related, restaurants and others. The pattern of floors, size of shops, street corners and widths of streets were also analysed. The results are as follows: 1. In terms of numbers of firms in living related function, Pusan Station shopping district is the $7{\sim}8th$ ranked central place among nine the highest centers within Pusan City. Pusan Station shopping district has not much promoted vertical spatial differentiation comparatively, and also it's intensity of land use is the lower among nine the highest centers. It is presented that intimate relationship between intensity of vertical land use and classes of central places within the city. The ratio of inns and hotels in Pusan Station shopping district is third ranked in Pusan City. And the size of inns and hotels in this area is the most largest among the nine highest ranked central places within Pusan City. These presented that the traditional characteristics of station area as a special functioned shopping district. Inns and hotels mainly located along the narrower and back street. And it forms agglomerated areas or 'an alley of inns' at the inner parts of blocks, some like a 'hidden flower'. In Korea, 'alley' means that an area of specialization gains the prestige, traditionally. 2. Restaurants mainly locate along the narrower and back streets. And agglomerated areas of restaurants coincide with the agglomerated area of drinking places. It shows that these two kinds of functions need the same locational conditions. The ratio of Chinese restaurants is the highest in the Pusan Station shopping district. It's due to the agglomerated area these kinds of restaurants at the 'China town'. 3. Pusan Station shopping district has been formed along the streets within the residential areas. It's means that this shopping district now at the initial or middle growth era in development stage of shopping areas. 4. In general, wholesales and light manufacturing are located at peripheries within shopping district. But in Pusan Station shopping district, it dose not appear these spatial pattern. It shows that this area is lower ranked central place and not much progressed in spatial differentiation. 5. Particular firms which customers and workers have stayed more longer period of time are located at the far from the first floor. This vertical spatial differentiation is similar to the horizontal sequences. 6. Firms which have more ability of rental payment are located at street comers such as banks and pharmacies. In Pusan Station shopping district commercial facilities could not invade into the second third floors at narrower streets and first floor of back streets, still now.

• The Korean Journal of Pesticide Science
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• v.12 no.2
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• pp.148-154
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• 2008

This study was carried out to investigate the residue patterns of two insecticides, lambda-cyhalothrin and deltamethrin, commonly used for lettuce, under greenhouse conditions. The pesticides were sprayed with dilution of recommended and doubled doses onto lettuce. Their detection limits were $0.001\;mg{\cdot}kg^{-1}$ and mean recoveries at the fortification levels of 0.2 and $1.0\;mg{\cdot}kg^{-1}$ were from 101.17 to 104.25 and from 99.70 to 103.77%, respectively. The pesticides were gradually decreased in lettuce with time. Biological half-lives of lambda-cyhalothrin and deltamethrin were 1.7 and 1.4 days at the recommended dose and 1.8 and 1.4 days at the doubled dose, respectively. Initial residue amounts of lambda-cyhalothrin and deltamethrin at the recommended and doubled doses exceeded their MRLs. However, the residue levels of the pesticides in the crop sampled at harvest were less than their MRLs. The ratios of the estimated daily intake (EDI) to acceptable daily intake (ADI) by intake the crop harvested 10 days after spraying were less than 1% of their ADIs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.121-126
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• 1999

In order to degrade chitin by enzymatic hydrolysis, it is required from screening highly active deacetylase. To this end, we examined three fungal strains and it turned out that Mucor rouxii produced highly active deacetylase, this enzyme exhibited the highest enzymatic activity against colloidal chitin. The conditions for growing Mucor rouxii are as follows; the effective carbon source, nitrogen source, adequate initial pH, temperature and incubation time were $2\%$ glucose, $1.33\%$ yeast extract, $0.66\%$ pepton, 4.5, $25{\pm}2^{\circ}C$ and 48hr, respectively. The optimum pH and temperature for purified enzyme activity were 5.5 and $40^{\circ}C$, respectively. The purified enzyme was stable at pH ranging from 4.5 to 5.5. However, the enzyme activity was decreased to less than $50\%$ at pH blow 45 and above 7.5. At temperatures above $50^{\circ}C$, the enzyme activity was decreased remarkably. The enzyme was inhibited by LiC1, $HgCl_2$, and $BaCl_2$, but stimulated by $CaCl_2$ and $ZnC1_2$, The activity of purified enzyme was increased by L-cysteine and 2-mercaptoethanol, while decreased by O-phenanthroline, p-CMB, EDTA, and iodoacetate. The $K_m$ and the $V_{max}$ value of purified enzyme were $1.2\%$ and 59.5 U/mg, respectively. The deacetylation activity of purified enzyme was not detected at optimal reaction condition when chitin particle suspension was used.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.4
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• pp.445-456
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• 2009

Statement of problem: Many studies have been conducted to improve the primary stability of implants by providing bioactive surfaces via surface treatments. Increase of surface roughness may increase osteoblast activity and promote stronger bonding between bone and implant surface and it has been reported that bioactive surface or titanium can be obtained through alkali and heat treatment. Purpose: The purpose of this study was to evaluate the stability of alkali and heat treated implants via histomorphometric analysis. Material and methods: Specimens were divided into three groups; group 1 was the control group with machined surface, the other groups were treated for 24 hours in 5 M NaOH solution and heat treated for 1 hour at $600^{\circ}C$ in the atmosphere (group 2) and vacuum (group 3) conditions respectively. Surface characteristics were analyzed and fixtures were implanted into rabbits. The specimens were histologically and histomorphometrically compared according to healing periods and change in bone composition were analyzed with EPMA (Electron Probe Micro Analyzer). Results: 1. Groups treated with alkali and heat showed increase of oxidization layer and Na ions. Groups 2 which was heat treated in atmosphere showed significant increase of surface roughness (P<.05). 2. Histomorphometric analysis showed significant increase in BIC (bone to implant contact) according to increase in healing period and there was significant increases in groups 2 and 3 (P<.05). 3. BA(bone area) ratio showed similar results as contact ratio, but according to statistical analysis there was significant increase according to increase in healing period in group 2 only (P<.05). 4. EPMA analysis revealed no difference in gradation of bone composition of K, P, Ca, Ti in surrounding bone of implants according to healing periods but groups 2 and 3 showed increase of Ca and P in the initial stages. Conclusion: From the results above, it can be considered that alkali and heat treated implants in the atmosphere have advantages in osseointegration in early stages and may decrease the time interval between implantation and functional adaptation.

• Sleep Medicine and Psychophysiology
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• v.4 no.1
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• pp.57-65
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• 1997

As jet lag of modern travel continues to spread, there has been an exponential growth in popular explanations of jet lag and recommendations for curing it. Some of this attention are misdirected, and many of those suggested solutions are misinformed. The author reviewed the basic science of jet lag and its practical outcome. The jet lag symptoms stemed from several factors, including high-altitude flying, lag effect, and sleep loss before departure and on the aircraft, especially during night flight. Jet lag has three major components; including external de synchronization, internal desynchronization, and sleep loss. Although external de synchronization is the major culprit, it is not at all uncommon for travelers to experience difficulty falling asleep or remaining asleep because of gastrointestinal distress, uncooperative bladders, or nagging headaches. Such unwanted intrusions most likely to reflect the general influence of internal desynchronization. From the free-running subjects, the data has revealed that sleep tendency, sleepiness, the spontaneous duration of sleep, and REM sleep propensity, each varied markedly with the endogenous circadian phase of the temperature cycle, despite the facts that the average period of the sleep-wake cycle is different from that of the temperature cycle under these conditions. However, whereas the first ocurrence of slow wave sleep is usually associated with a fall in temperature, the amount of SWS is determined primarily by the length of prior wakefulness and not by circadian phase. Another factor to be considered for flight in either direction is the amount of prior sleep loss or time awake. An increase in sleep loss or time awake would be expected to reduce initial sleep latency and enhance the amount of SWS. By combining what we now know about the circadian characteristics of sleep and homeostatic process, many of the diverse findings about sleep after transmeridian flight can be explained. The severity of jet lag is directly related to two major variables that determine the reaction of the circadian system to any transmeridian flight, eg., the direction of flight, and the number of time zones crossed. Remaining factor is individual differences in resynchmization. After a long flight, the circadian timing system and homeostatic process can combine with each other to produce a considerable reduction in well-being. The author suggested that by being exposed to local zeit-gebers and by being awake sufficient to get sleep until the night, sleep improves rapidly with resynchronization following time zone change.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.168-176
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• 2011

Purpose: This study aims at investigating the influence of various insertion torques on thermal changes of bone. A proper insertion torque is derived based on the thermal analysis with two different implant designs. Materials and methods: For implant materials, bovine scapula bone of 15 - 20 mm thickness was cut into 35 mm by 40 - 50 mm pieces. Of these, the pieces having 2 - 3 mm thickness cortical bone were used as samples. Then, the half of the sample was immersed in a bath of $36.5^{\circ}C$ and the other half was exposed to ambient temperature of $25^{\circ}C$, so that the inner and surface temperatures reached $36.5^{\circ}C$ and $28^{\circ}C$, respectively. Two types of implants ($4.5{\times}10\;mm$ Br${\aa}$nemark type, $4.8{\times}10\;mm$ Microthread type) were inserted into bovine scapula bone and the temperature was measured by a thermocouple at 0.2 mm from the measuring point. Finite element method (FEM) was used to analyze the thermal changes at contacting surface assuming that the sample is a cube of $4\;cm{\times}4\;cm{\times}2\;cm$ and a layer up to 2 mm from the top is cortical bone and below is a cancellous bone. Boundary conditions were set on the basis of the shape of cavity after implants. SolidWorks was used as a CAD program with the help of Abaqus 6.9-1. Results: In the in-vitro experiment, the Microhead type implant gives a higher maximum temperature than that of the Br${\aa}$nemark type, which is attributed to high frictional heat that is associated with the implant shape. In both types, an Eriksson threshold was observed at torques of 50 Ncm (Br${\aa}$nemark) and 35 Ncm (Microthread type), respectively. Based on these findings, the Microthread type implant is more affected by insertion torques. Conclusion: This study demonstrate that a proper choice of insertion torque is important when using a specific type of implant. In particular, for the Microthread type implant, possible bone damage may be expected as a result of frictional heat, which compensates for initial high success rate of fixation. Therefore, the insertion torque should be adjusted for each implant design. Furthermore, the operation skills should be carefully chosen for each implant type and insertion torque.

• Korean Journal of Food Science and Technology
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• v.11 no.1
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• pp.42-49
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• 1979

In order to evaluate the utility of the anthocyanins of Amaranthys tricolor L. as an edible pigment, the present study was undertaken to investigate the effects of pH. temperature, ascorbic acid, sugars and their degradation products, quercetin, thiourea, sodium pyrophosphate and metal ions on the stability of the anthocyanins in the model systems. The results obtained from this study were as follows. 1. The degradation of total anthocyanins was retarded as the pH levels decreased from 8.0 to 1.0. At pH 1.0, however. the initial degradation reaction proceeded faster than at pH 2.0 to 3.0 2. On heating in buffered aqueous solution at $80^{\circ}C$, the total anthocyanin content was higher at pH 2.0 than other pH levels. Increasing the storage temperature accelerated greatly the pigment degradation. In darkness at $40^{\circ}C$, after 10 days, only 19% of the original amount was left, while at $2^{\circ}C$, under the same conditions of storage, approximately 90% of the pigment was retained. The half-life of the pigment, 63.0 days at $2^{\circ}C$, shortened to 1. 7 days at $40^{\circ}C$. 3. An increase in ascorbic arid concentration from 0. 15 to 0.50 mg/ml lowered the anthocyanin retention. 4. There was no significant difference between glucose and fructose in anthocyanin degradation effect. Furfural was more effective than other sugar degradation products, formic acid or levulinic acid in accelerating anthocyanin breakdown. 5. Neither quercetin nor sodium pyrophosphate had a protective effect on the anthocyanins in the presence of ascorbic acid, while, in the systems 0.5 or 1 mg/ml of thiourea with $150{\;}{\mu}g/ml$ of ascorbic acid, the loss of anthocyanins was significantly reduced. 6. Both mercuric and cupric ions in 30 ppm greatly accelerated anthocyanin degradation.