• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.822-828
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• 1998

Binary system of water and polyoxyethylene dodecyl ether, $C_{12}H_{25}(OCH_2CH_2)nOH$, have been studied by $^1H$ NMR techniques. For n=5($C_{12}EO_5$) and n=8($C_{12}EO_8$), the self-diffusion coefficients of nonionic surfactants in the isotropic phase($L_1$) have been measured by using pulsed field gradient technique for a range of temperature and concentrations. In addition the line widths of the different proton signals have been monitored, and samples of some liquid crystalline characteristic were also studied. Dramatic Broadening of the methylene signals of the alkyl($C_{12}H_{25}$) chain is observed as the hexagonal liquid crystalline phase is approached in the $C_{12}EO_5-$water system, while only small broadening is observed in the $C_{12}EO_8-$water system. It was shown that there was a growth of $C_{12}EO_5$ micelles to rods with increasing concentrations, while the $C_{12}EO_8-$ micelles at low temperature remain small in the concentration range. The self-diffusion coefficients of the surfactants decrease rapidly with increasing concentration until a minimum is reached after which there is slow increase. The location of the minimum point occurs at lower concentrations the temperature is close to the cloud point, where the system separate into two isotropic phase. In the line width studies, broadening is found at a certain temperature interval when the concentration is increased in the $C_{12}EO_5$ system. The results indicate that the surfactant aggregates grow in size at the cloud point is approached. The aggregates seem to be flexible and probably not to be of a definite shape close to the cloud point. In the $C_{12}EO_8$ system, the micelles are much less affected by an increase in temperature and micellar growth can't be unambiguously established. The methylene signals of the ethylene oxide moieties consistantly show narrower $^1H$ signals, showing that in the aggregates they are less ordered than the chain methylenes. The various changes in aggregate size and shape are correlated with the stability ranges of the isotropic and liquid crystalline phases according to phase diagrams from the literature. Both aggregate size and phase structure are in qualitative agreement with concentration based on the effective shape of the molecules at different temperature and concentration.

• Journal of Environmental Impact Assessment
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• v.29 no.5
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• pp.391-402
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• 2020

Health Impact Assessment based on municipal law is performed and written in the sanitary and public health part in the current environmental impact assessment. Residential development projects such as housing site development etc., are not subject to health impact assessment under Article 13 of the Environmental Health Act. However, health impact assessment is conducted partially based on the review that health impact assessment targets which are identified among substances emitted from pollutants nearby industrial complexes should be assessed risk (including carcinogenic and non-carcinogenic) at the stage of the environmental impact assessment consultation. Although residential development projects do not have plans for pollutant emitting facilities that emit hazardous air pollutants, there is a possibility that residents might be affected by pollutants from industrial complex near residential area in the future. In this study, Health impact assessment was conducted to examine the impact on residents in planned areas by analyzing previous residential development projects. We predicted future impact by using the literature survey results on surrounding area (case1) and conducting contribution analysis (case2) and predicting exposure concentration of carcinogenic substances applying Atmospheric Diffusion Model (AERMOD). By this study, we concluded that applying on-site survey, contribution analysis and prediction of exposure concentration by using AERMOD complementarily will be effective to assess the health impact to the receptors by pollutants from industrial complexes near the planned zone.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.10
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• pp.14-22
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• 2010

The source/channel/drain regions are formed by ion implantation with different dopant types of $n^+/p^{(+)}/n^+$ in the fabrication of the conventional n-type metal-oxide-semiconductor field effect transistor(NMOSFET). In implementing the ultra-small devices with channel length of sub-30 nm, in order to achieve the designed effective channel length accurately, low thermal budget should be considered in the fabrication processes for minimizing the lateral diffusion of dopants although the implanted ions should be activated as completely as possible for higher on-current level. Junctionless (JL) MOSFETs fully capable of the the conventional NMOSFET operations without p-type channel for enlarging the process margin are under researches. In this paper, the optimum design of the JL MOSFET based on silicon nanowire (SNW) structure is carried out by 3-D device simulation and the basic radio frequency (RF) characteristics such as conductance, maximum oscillation frequency($f_{max}$), current gain cut-off frequency($f_T$) for the optimized device. The channel length was 30 run and the design variables were the channel doping concentration and SNW radius. For the optimally designed JL SNW NMOSFET, $f_T$ and $f_{max}$ high as 367.5 GHz and 602.5 GHz could be obtained, respectively, at the operating bias condition $V_{GS}$ = $V_{DS}$ = 1.0 V).

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.36-42
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• 2005

This study examined the feasibility of producing sulfuric acid and ammonia water from ammonium sulfate solution using two-compartment electrodialysis with a bipolar membrane (EDBM). Electrodialysis experiments were carried out with 20 wt% ammonium sulfate at different current densities and sulfuric acid concentrations in a concentrate compartment. The current efficiency increased with the current density from 25 to $100\;mA/cm^2$. Nevertheless, the efficiency was relatively low compared with that of general desalting electrodialysis, owing to the diffusion of sulfuric acid from the concentrate compartment to the diluate. The diffusion rate through the anion exchange membrane increased with the sulfuric acid concentration in the concentrate compartment, which decreased the current efficiency. Conversely, the electrical resistance decreased with increasing current density owing to the Joulian heat generated during water dissociation in the transition region of the bipolar membrane under a high electric field. From the experimental results, we concluded that operating at a higher current density is effective from the perspective of current efficiency and electrical resistance when producing sulfuric acid and ammonia water from ammonium sulfate using a two-compartment EDBM process. Further studies on the effects of increasing the sulfuric acid concentration on current efficiency are required to apply the EDBM process practically.

• Nuclear Engineering and Technology
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• v.13 no.4
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• pp.264-276
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• 1981

A simulation procedure which can represent time-dependent nuclear characteristics of TRIGA Mark-III reactor is developed. CITATION, a multi-group diffusion-depletion program, has been utilized as calculational tool. The group structure employed in this study consists of 7 groups: -3-fast and 4-thermal-which is conventionally utilized in TRIGA type reactor analysis. Three-dimensional nuclear characteristics are synthesized by combining results from two-dimensional plane calculation and two-dimensional cylinder calculation, since direct three-dimensional approach is not yet possible. An effort ia made to develope a method which can extract effective zone and group dependent bucklings by neutron diffusion theory rather than conventional zone and/or group independent Ducklings by neutron transport theory, since neutron leakage is quite high for small core such as research reactors. It is turned out that the method developed in this study gives satisfactory results. The calculation is performed under assumptions that all control rods are fully withdrawn, that no samples are inserted in the irradiation holes and that the core is located in the center of the reactor pool. Burnup-dependent variation of core excess reactivity, time dependent change of Xe-135 poisoning and reactivity worth of rotary specimen rack are calculated and compared with operation records. Neutron flux and power distribution as well as neutron spectrum in each irradiation .facility are presented.

• Journal of the Korean Home Economics Association
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• v.17 no.4
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• pp.117-127
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• 1979

This study attempts to shed additional light on the national diffusion process and interaction of welfare services for children and mothers. The central hypothesis examined is the following : In general, the implant of social welfare system is first considered on the characteristics of their own socio-economics , and diffusion prodess of welfare services tends to occur faster in countries with open sicieties than in countries where entry barriers are high and society ranking rigid. The scope of the study is limited in several ways. Attention is concentrated on the agency of woman in the belief that an in-depth case study of one field can yield more insight than a less detailed investigation embracing a number of social welfare systems. The angency of woman is selected for several reasons. a) It is important the agency of woman alone produce more effective than services affecting both the child welfare and women's libertion bradually. Moreover, these services will form the heart of mother's welfare. b) The services of women's agency is gradually wide spread, since a role of government is still negligible before a full realization of economic income. c) The services of women agency is a prime example of a social welfare. d) statistical data and other information are more readily available. One of major findings of our study is the existence of the barriers inhibiting child welfare form " motherhood cult". Despite all the distinct advantages for mother and child , social attitudes appear to be some resistant on child welfare system among men and women even the agenices of women. What is surprised is the extent of the awareness that strategies of women's agency to liberate woman and to increate activities of women involve the strategies to liberate child. The conviction that solving application problems for child welfare in line with the activities of agency by women offer greater freedom and more advantage to mother are not apparent on the data collected from 18 of multi-functional agencies in our country. there are little sign that such agencies cooperate toward attainment of common goals. The intensive early focus of the movement on consciousness raising is a necessary beginning and such efforts by women's organizations would help both in the continuous evolution of women and child. Some of the agencies offer a variety of services to women and children, others are specialized in that they offer fewer services or even only one. Social welfare agenices giving service to children and their families are identified by various names usually women service and child welfare from govern , mental agency and voluntary public agency to foreign aided. What is totally missing , however, is an integrated synthesis of child welfare program Through women's agency. Social changes to occur, but delineation of appropriate and comprehensive social policy is also necessary at this point at this point since efforts, social changes and polices must be well coordianted and focused, as well as mutually supprotive and reinforcing.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.271-280
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• 2019

We investigated the control efficacy and phytotoxicity of unmanned aerial vehicle-applied pesticides against the insect Spodoptera exigua, a major emerging pest in Chinese cabbage. Phytotoxicity was investigated in cabbage and 7 crops cultivated in the perconducted on 8 surrounding crops including Chinese cabbage at 1 to 2 times the recommended pesticide dosage. We treated cabbage fields with spinetoram suspension concentrate (16×), methoxyfenozide, sulfoxaflor suspension concentrate (16×). Then, we used water-sensitive paper to measure the distribution pattern of falling pesticide particles and the degree of coverage. Two of the pesticides showed 97% control efficacy, however, control efficacy might differ in resistant populations. Phytotoxicity was not observed in Chinese cabbage and the 7 surrounding crops treated with 1 to 2 times the recommended pesticide dosage. Analysis of the distribution pattern of falling pesticide particles revealed that breeze caused particle diffusion. Thus, wind is an important factor affecting the uniform treatment and diffusion of multicopter-applied pesticides. It follows that setting optimal conditions is necessary for effective control and treatment.

• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.143-150
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• 1997

In this study, doffusion barrier properties of 1000 $\AA$ thick molybdenum compound(Mo, Mo-N, $MoSi_2$, Mo-Si-N) films were investigated using sheet resistance measurement, X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Scanning electron mircoscopy(SEM), and Rutherford back-scattering spectrometry(RBS). Each barrier material was deposited by the dc magnetron sputtering and annealed at 300-$800^{\circ}C$ for 30 min in vacuum. Mo and MoSi2 barrier were faied at low temperatures due to Cu diffusion through grain boundaries and defects in Mo thin film and the reaction of Cu with Si within $MoSi_2$, respectively. A failure temperature could be raised to $650^{\circ}C$-30 min in the Mo barrier system and to $700^{\circ}C$-30 min in the Mo-silicide system by replacing Mo and $MoSi_2$ with Mo-N and Mo-Si-N, respectively. The crystallization temperature in the Mo-silicide film was raised by the addition of $N_2$. It is considered that not only the $N_2$, stuffing effect but also the variation of crystallization temperature affects the reaction of Cu with Si within Mo-silicide. It is found that Mo-Si-N is the more effective barrier than Mo, $MoSi_2$, or Mo-N to copper penetraion preventing Cu reaction with the substrate for $30^{\circ}C$min at a temperature higher than $650^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.46 no.2
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• pp.68-74
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• 2013

For the coating of diamond films on WC-Co tools, a buffer interlayer is needed because Co catalyzes diamond into graphite. W and Ti were chosen as candidate interlayer materials to prevent the diffusion of Co during diamond deposition. W or Ti interlayer of $1{\mu}m$ thickness was deposited on WC-Co substrate under Ar in a DC magnetron sputter. After seeding treatment of the interlayer-deposited specimens in an ultrasonic bath containing nanometer diamond powders, $2{\mu}m$ thick nanocrystalline diamond (NCD) films were deposited at $600^{\circ}C$ over the metal layers in a 2.45 GHz microwave plasma CVD system. The cross-sectional morphology of films was observed by FESEM. X-ray diffraction and visual Raman spectroscopy were used to confirm the NCD crystal structure. Micro hardness was measured by nano-indenter. The coefficient of friction (COF) was measured by tribology test using ball on disk method. After tribology test, wear tracks were examined by optical microscope and alpha step profiler. Rockwell C indentation test was performed to characterize the adhesion between films and substrate. Ti and W were found good interlayer materials to act as Co diffusion barriers and diamond nucleation layers. The COFs on NCD films with W or Ti interlayer were measured as less than 0.1 whereas that on bare WC-Co was 0.6~1.0. However, W interlayer exhibited better results than Ti in terms of the adhesion to WC-Co substrate and to NCD film. This result is believed to be due to smaller difference in the coefficients of thermal expansion of the related films in the case of W interlayer than Ti one. By varying the thickness of W interlayer as 1, 2, and $4{\mu}m$ with a fixed $2{\mu}m$ thick NCD film, no difference in COF and wear behavior but a significant change in adhesion was observed. It was shown that the thicker the interlayer, the stronger the adhesion. It is suggested that thicker W interlayer is more effective in relieving the residual stress of NCD film during cooling after deposition and results in stronger adhesion.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1126-1134
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• 1996

The physical characteristics changes of carrots during drying were studied to minimize the quality degradation by applying improved drying process and pretreatment method. Physico-chemical properties of the product were analyzed, and then, drying mechanisms were explained by diffusion coefficients and drying models. In hot air drying process, the drying and rehydration efficiencies were high at low relative humidity and high temperature. Browning degree and specific volume also showed similar trend to drying efficiency. Diffusion coefficient, which describes moisture transfer, was also high at low relative humidity and at high temperature. It was verified using. Arrhenius equation that drying process was influenced by temperature. It was also observed during experiment that temperature changes were more effective in drying than relative humidity changes. Quadratic model was the most fittable in explaining the process. As a result of analyzing the experimental data with respect to the drying time, the contents of carotene and moisture could be modeled as a polynomial. As the air velocity increased, drying performance and rehydration efficiency increased.