Earticle

Amount of residual ink solvent on the packaging materials from Korea, Japan and Europe was measured and compared. The amount of packaging materials from Korea was much higher than that of Japan and Europe. To reduce the residual amounts of ink solvent, aging condition of printed packaging materials including aging time and temperature was modified and evaluated. Aging with high temperature and short time (60℃ and 24 hours) was more effective for reduction of residual amount of ink solvent than that with low temperature and long time. To find out change of reduction pattern of residual amount of solvent according to plastic packaging material, several monolayer and multilayer packaging materials were selected. Among the monolayer packaging materials, the amount of EVOH and PET was lower than that of polyolefin plastic film including PE and PP. PP/EVOH/PET among the selected multilayer film showed the lowest amount of residual ink solvent on food packaging materials. Result of this research revealed that the residual amount of ink solvent can be reduced by proper selection of aging condition with and by appropriate application of mutilayer plastic film.

Migration behavior of selected solvents and food samples showed differences of the chemical structures and polarities, the food samples which have similar polar expresses more higher affinity than different polar degrees. Water which is polar has a highest partitioning coefficient values on polar isopropanol, and oil which is nonpolar has highest partitioning value on non-polar toluene. The increasing order of partitioning values was accord with increasing water contents in food samples. It is showed that the wheat flour with 13.2% moisture content has the highest partitioning coefficient values on the isopropanol with -OH. Kp value of sugar showed remarkable lower partitioning coefficient values than other food samples due to high degree crystallinity. This phenomenon can be predictable with ${\delta}$ values, because order of partitioning coefficient values which comes out through the experiment and the sequence of Hildebrand solubility parameter value difference between food sample and printing ink solvent correspond almost. This Hildebrand solubility parameter value can be easily applied to the food package industry because the effect of food-safety can be considered without passing through complicated steps by using this method.

The partitioning behavior of the five printing ink solvents in nine lab-made cookies with various sugar and water content at 25${^{\circ}C}$ was studied to find out the presence and effects of interaction between the two ingredients on partitioning behavior in cookies. Solvents were ethyl acetate, hexane, isopropanol, methyl ethyl ketone and hexane. It was observed that the partition coefficient (the solvent concentration in food compared to that in air, Kp) decreased as sugar increased in all case and increased as water content increased for all compounds except toluene. Statistical analysis by the F-test method was used to determine the significance of sugar-water interactions, as well as other single factors on partitioning behavior of each solvent. Sugar content alone had no significant effects, but the crystallinity of sugar, as changed by water content, affected the partitioning behavior of the five solvents significantly. Parameter estimation for each significant factor by SAS program yielded a regression equation, which was used to predict the partitioning behavior in the finished cookie. Kp values from the regression equation could be determined more precisely by applying a correction term for the interaction between sugar and water to the Kp values of each ingredient after baking.

In normal cells, cell to cell contact at full cell confluency inhibits cell growth. However, if cell to cell contact is being dissociated, normal cells reach their end of life by the phagocytosis of macrophage via 'programmed cell death', named 'apoptosis'. On the other hand, in cancer cells (especially, cancer stem cells), cell to cell contact can not inhibit cell growth. As a result, cancer stem cells can grow beyond full cell confluency. When cancer cells reach full cell confluency, they either stay at confluence stage or must be made transition from epithelial to mesenchymal form by cadherin switch(antiapoptotic program). These behavioral patterns of cancer stem cells are called "EMT"[2,20]. The underlying causes for such difference have not been known well until now. But this difference is assumed to be occurred by loss of cellular differentiation and coordination of proliferation[5]. As approaching the reason of such disorders with mechano-molecular biology, it was predicted using a mechanobiological model that if cellular unbalanced force is caused between cell to ECM and cell to cell adhesion, the molecular crosstalk is disintegrated between E-cadherin and EGFR Signaling Networks in cell to cell contacts and the attributes such as morphological change of cancer cells, motility, invasion, anticancer drug resistance, etc are acquired, and they were established by experimental method[5]. This study is to report the research results for an idea that the neural network development is a meaningful method of prediction system on cancer behavior patterns through such methods.

Increasing use of plastics in food packaging materials has led to the issue of food-plastic packaging materials`s mutual interactions. Although the plastic packaging materials are generally considered as inert, migration and sorption of fatty materials are some of the problems associated with their use. So, this work investigated the compatibility of three structurally different polymers, polypropylene (PP), polyethyleneterephthalate (PET) and ethylene vinyl alcohol copolymer (EVOH) with some structurally different food fats. The main goal was to study the sorption of food fats by the plastic films and to see what extent mechanical properties of the plastic films was affected by plasticization effect due to sorption of fatty materials. PP, PET, and EVOH films was immersed in pure triglycerides, and then extracted with hexane and analyzed for the amounts of fat migrated. The sorbed films were also investigated for change in mechanical properties. Result showed that structural factor of the films and fatty materials plays important role in th migration process. The fat with the simplest structure are migrated more easily that the fat with more complex structure. However, structural effect of migration was varied according to degree of crystallinity and density of plastic films. In addition to that, polarity of plastic film was affected migration of fatty materials significantly. Additional research is needed to justify the reason why migration of fatty materials into the films was affected by polarity and structural integrity.

The in creasing use of plastics in food packaging mat erials has led to the issue of food - packaging mutu al inter actions from residues in the plastics . Plastic films are commonly print ed by using solvent - based ink t o decorate the packaged food for consumer attention. However, the residual solvents can not be completely removed and they can migrat e into the contained food which lead t o undesir able off- flavors. Partitioning (Kp) of printing ink solvent s was studied in two types of pla stic films with differ ent chemical structu e and polarity. At 25 。C, Kp of toluene is higher than that of isopropan ol in PP, but isopropanol showed higher Kp value than toluene in EVOH. This showed that polarity had a significant effect on the partitioning of printing ink solvents into the plastic films. Printing solvent s had a higher affinity to the polymer with similar polarity that it did to the different one.

Migration behavior of printing ink solvents on three types of chocolates with different fat content and fat compositions (different crystallinity) was investigated. Even though chocolate cream (29%) has lower fat content (29%) than that of chips (48%), it showed higher degree of migration. However, with increasing temperature, degree of migration was depended on mainly fat content. This result indicated that degree of migration was mainly affected by crystallinity at below melting point of chocolate, but the effect was diminshed as the temperature was close to melting temperature.

Dissipative particle dynamics simulations of bead-spring dumbbell models under microchannel flow were performed and the effects of the deformation on their migration behavior were discussed. Dumbbells were found to migrate toward the walls or the channel center depending on the stiffness. Stiff dumbbells migrated toward the walls. In any cases, the dumbbells were found to have a stronger tendency to move toward the channel center in more deformable conditions.

The quantity, process and kinetics of di-(2-ethylhexyl)phthalate (DEHP) migration in the 30/70 and 40/60 poly(vinylchloride) (PVC)/DEHP blends were investigated using gas chromatograph. A thin and flexible PVC sheet was soaked in surrounding medium (SM) of water/ethanol mixture and acetonitrile with constant stirring to release DEHP. By observed concentration of DEHP in the SM, it is found that acetonitrile is more intense in DEHP migration than water/ethanol mixture. In addition the amount of extracted DEHP is proportional to the leaching temperature and added ratio of DEHP. The behavior of DEHP migration from flexible PVC sheets was described by the Ficks's law with $2.72-10.1\;{times}\;10^{-10}$ cm²/s of the diffusion coefficients.

A safety assessment of radioactive waste repositories is a mandatory requirement process because there are possible radiological hazards owing to radionuclide migration from radioactive waste to the biosphere. For a reliable safety assessment, it is important to establish a parameter database that reflects the site-specific characteristics of the disposal facility and repository site. From this perspective, solubility, a major geochemical parameter, has been chosen as an important parameter for modeling the migration behavior of radionuclides. The solubilities were derived for Am, Ni, Tc, and U, which were major radionuclides in this study, and on-site groundwater data reflecting the operational conditions of the Gyeongju low and intermediate level radioactive waste (LILW) repository were applied to reflect the site-specific characteristics. The radiation dose was derived by applying the solubility and radionuclide inventory data to the RESRAD-OFFSITE code, and sensitivity analysis of the dose according to the solubility variation was performed. As a result, owing to the low amount of radionuclide inventory, the dose variation was insignificant. The derived solubility can be used as the main input data for the safety assessment of the Gyeongju LILW repository in the future.

In Lead-based reactor (LBR) severe accident, the meltdown and migration inside the reactor core will lead to fuel fragment concentration, which may further cause re-criticality and even core disintegration. Accurately predicting the migration and solidification behavior of melt in LBR severe accidents is of prime importance for safety analysis of LBR. In this study, the Moving Particle Semi-implicit (MPS) method is validated and used to simulate the migration and solidification behavior. Two main surface tension models are validated and compared. Meanwhile, the MPS method is validated by the L-plate solidification test. Based on the improved MPS method, the migration and solidification behavior of melt in LBR severe accident was studied furthermore. In the Pb-Bi coolant, the melt flows upward due to density difference. The migration and solidification behavior are greatly affected by the surface tension and viscous resistance varying with enthalpy. The whole movement process can be divided into three stages depending on the change in velocity. The heat transfer of core melt is determined jointly by two heat transfer modes: flow heat transfer and solid conductivity. Generally, the research results indicate that the MPS method has unique advantage in studying the migration and solidification behavior in LBR severe accident.

The complex 2-dimensional movements of fish during an annual migration circuit were generated and simulated by a chaotic model of fish movement, which was expanded from a small-scale movement model. Fish migration was modeled as a neural network including stimuli, central decision-making, and output responses as variables. The input stimuli included physical stimuli (temperature, salinity, turbidity, flow), biotic factors (prey, predators, life cycle) and landmarks or navigational aids (sun, moon, weather), values of which were all normalized as ratios. By varying the amplitude and period coefficients of the klinokinesis index using chaotic equations, model results (i.e., spatial orientation patterns of migration through time) were represented as fish feeding, spawning, overwintering, and sheltering. Simulations using this model generated 2-dimesional annual movements of sea bream migration in the southern and western seas of the Korean Peninsula. This model of object-oriented and large-scale fish migration produced complicated and sensitive migratory movements by varying both the klinokinesis coefficients (e.g., the amplitude and period of the physiological month) and the angular variables within chaotic equations.

이 연구에서는 비수도권에서 수도권(Seoul Metropolitan Area)으로 이주한 자의 이주 결정요인과 이주지에서의 주거문화에 대한 실태를 분석한다. 이용한 자료는 5년마다 통계청에서 발표하고 있는 ‘2010 인구주택총조사’ 2% 표본자료이다. 이 연구에서는 먼저 이주결정함수를 추정하였다. 추정결과에 의하면 남성보다 여성, 기혼자보다 미혼자가 이주경향이 높았다. 그리고 연령이 낮을수록, 교육수준이 높을수록, 가구원수가 작을수록, 거주지 평균소득이 낮을수록, 그리고 수도권에서 거리가 짧을수록 이주경향이 높은 것으로 나타났다. 이것은 전통적인 인적자본 인구이동이론과 합치되는 것이다. 다음으로 이주자들의 주거문화에 대한 실태분석의 일환으로 자기 집 소유 결정함수를 추정하였는데 여성보다 남성, 미혼자보다 기혼자, 그리고 교육수준이 높을수록 자기 집 소유경향이 높았다. 그리고 서울보다는 경기, 경기보다는 인천 거주자가 자기 집 소유경향이 높았다. 마지막으로 비수도권에서 수도권으로 이주한 자를 대상으로 연령과 교육연수의 자기 집 소유에 대한 한계효과를 구하였다. 한계효과 추정결과에 의하면 연령이 1세 증가하면 자기 집 소유 확률이 약 1%P 증가하고, 교육연수가 1년 증가하면 자기 집 소유 확률이 0.9% 증가하는 것으로 추정되었다.

This study investigates the determinants of migration and housing culture for the immigrants to Seoul Metropolitan Aarea. The data used here is 2% sample data of '2010 Population and Housing Census' released every 5 years by Statistics Korea. According to the estimated migration determination function, female, young-aged and unmarried have higher migration tendencies than their counterparts. In addition, the higher education level is, the smaller household size is, the lower average income is, and the closer from the Seoul Metropolitan Area is, the higher is the tendency to migrate. These results are consistent with the implications of traditional migration theory. According to the estimation of house ownership determination function, male, married, and highly educated have higher tendencies of house ownership than their counterparts. Inside of Seoul Metropolitan Area, the tendencies of house ownership is high in the order of Incheon, Gyeonggi, and Seoul. Finally, marginal effects of age and education level on house ownership are estimated. In case of people aged older than 30, marginal effect of age is 1%P. In addition, the one-year increase of education length brings 0.9%P increase of house ownership.

어군탐지기를 이용하여 어군의 분포와 그 행동생태를 계측하기 위한 연구의 일환으로 어군의 연직적인 일주회유이동 및 초음파산란강도의 변동특성을 검토하고, 또한 수온의 연직구조와 어군의 연직분포특성과의 관계, 선박의 항주상태에 따른 어군의 행동반응 등을 현장실험을 통하여 검토, 고찰한 결과를 요약하면 다음과 같다. (1) 어군의 공간분포특성은 수온의 연직구조와 밀접한 관계가 있음을 알 수 있었다. (2) 동중국해 중앙부에서 일출 직전까지 수온약층 바로 아래쪽에 군집하고 있던 칼오징어와 전갱이 어군이 일출과 더불어 해저를 향해 급속히 하강하는 일주회유이동이 관찰되었고, 그 하강속도는 0.24m/min이었다. (3) 수온약층이 탁월했던 제주도 서방해역과 대만 북부해역을 대상으로 어군의 연직분포특성과 수온의 연직구조와를 상호 비교 분석한 결과, 표층과 저층의 수온차가 크고, 또 중층에 뚜렷한 수온약층이 형성되어 있는 경우, 전갱이와 칼오징어군은 야간에 수온약층의 바로 아래쪽에 농밀하게 군집하는 특성을 나타내고, 또 표층과 저층의 수온차가 적은 경우에 있어서는 표층까지 완전히 부상하여 군집하는 경향을 나타내었다. (4) 선박을 정선시킬 때, 선저 직하에 분포하는 어족생물이 급히 연직적으로 하향 이동하는 도피행동을 나타내었다. 그러나, 그 후 시간이 경과함에 따라서 다시 원래의 유영층으로 상향이동하는 행동패턴을 나타내었다. 한편, 수온약층을 경계로 하여 상층과 하층에 분포하는 어족생물의 행동패턴에도 차이가 있었는데, 수온약층 아래쪽에 있어서는 어군이 현저한 도피행동을 나타내었지만, 그 위쪽에 있어서는 그러한 징후가 관찰되지 않았다. 이와 같은 현상은 수온약층 아래쪽에는 유영성이 강한 어족생물이, 그 위쪽에는 유영성이 약한 어족생물이 군집하고 있었기 때문이라고 판단된다. 당시 이 해역에서 행한 저층 트롤의 주요 어획물은 물메기, 살오징어, 삼치 등이었다.

Hydroacoustic surveys were conducted in the East China Sea, in the summers of 1990-1991 to investigate the distribution and migration behavior of fish, such as the diel changes in the distributions of fish, the thermoselection behavior of fish, and the fish reactions to a surveying vessel. The hydroacoustic observations were taken with a scientific echo sounder operating at 50kHz and a microcomputer-based echo processor. Fish samples were collected by bottom trawling and temperature was measured with a DBT system. The patterns of fish distributions were compared with the vertical profiles of water temperature. The results obtained can be summarized as follows: 1. The time series of hydroacoustic observations on the downward migration at dawn in the central region of East China Sea showed that the migration rate was 0.24 m/min. In this region, most of the fish collected by bottom trawling during the surveys were squid (Photologio edulis f. budo) and horse mackeral (Trachurus japonicus). 2. The hydroacoustic observations, which together associated with temperature data, indicated that squid and horse mackeral concentrated nocturally in a narrow vertical band of thermocline, particularly in summer when the survey region was strongly stratified. This result suggest that the nocturnal vertical distribution of these species evidently is controlled by temperature. 3. When the survey vessel, that is running at a speed of 11 knots, has suddenly stopped, the fish which concentrated beneath the transducer showed a strong avoidance reaction in the form of rapid downward migration. After a few minutes, the descending reaction disappeared and the fish slowly began the upward migration toward their original swimming positions. Trawl data suggest that the fish, which showed the avoidance reaction, was Liparis tessellatus.

식품과 포장재의 상호 작용 정도를 나타내는 분배 계수는 포장재의 구조 및 특성은 물론이고 내용물의 구조적 특성 그 중에서도 결정도 (crystallinity)에 의해서도 많이 좌우되고 있다. 온도의 상승에 따른 식품 성분의 결정도 상실은 내용물과 포장재의 상호 작용 증가를 초래하고 있다. 따라서, 최근 가공 식품 개발의 큰 부분을 차지하고 있는 즉석 식품의 경우 제조시 가열은 물론 소비자에 의해 한번 더 가열된다는 점에서 내용물과 포장재의 상호 작용에 의한 이취 발생 및 식품 안전성에 부정적인 요인이 될 수 있다는 점에서 이에 대한 체계적인 연구가 필요하다고 하겠다.

Migration behavior of printing ink solvents on three types of chocolates with different fat content and fat compositions (different crystallinity) was investigated. Even though chocolate cream (29%) has lower fat content (29%) than that of chips (48%), it showed higher degree of migration. However, with increasing temperature, degree of migration was depended on mainly fat content. This result indicated that degree of migration was mainly affected by crystallinity at below melting point of chocolate, but the effect was diminshed as the temperature was close to melting temperature.