• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.2
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• pp.209-222
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• 1997

Authors surveyed the ground water near the waste disposed from a fiberglass production factory to confirm the presence of glassfiber in the water and to determine the effect of sampling conditions and storage on the recovery of fibrous materials in the ground water. Sample was collected at every 4 hours for 48 hours consecutively. After finishing the 48 hours sample, water sampling was done from each tap after repeated turning on and off the water for 30 seconds at each time. Sample was collected in the two 1.5 liter polyethylene bottle after vigorously shaking the bottle with the same water several times with the flowing tap water. At each paired sample, one bottle was stored stand still at room temperature, and the other sample was filtered immediately after sampling. Water was filtered on the Mixed Cellulose Ester filter with negative pressure. Each sample was divided into upper and lower layer. The other bottle was stored at room temperature standstill for 7 days and filtered in the same fashion as the other pair of sample did. Each MCE filter was divided into 4 pieces and one piece was treated with acetone to make it transparent. Each prepared sample was observed by two researchers under the light and polarizing microscopy, scanning electron microscopy and energy dispersive X-ra microanalysis. Fibers were classified by the morphology and polarizing pattern under the polarizing microscope, and count was done. 1. There was a significant fluctuation in number of the fibers, but there was no specific demonstrable pattern. 2. Non-polarizing fibers frequently disappeared after 7 days's storage. But cluster of fibers were found at the wall of the same container by scratching technique. 3. Polarizing fibers were usually found in between the filter and the manicure pasted area. Possible explanations for this phenomenon will be that either these fibers are very light or have electronic polarity. Hence, these fibers are not able to be attached on the surface of slide glass. 4. Under the scanning electron microscopic examination, the fibers which are not refractive under the light microscopy were identified as glassfiber. Other fibers which is refractive under the polarizing microscopy were identified as magnesium silicate fibers. It is strongly suggested that development of standardized method of sample collection and measurement of fibrous material in the water is needed.

• Korean journal of applied entomology
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• v.56 no.3
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• pp.253-259
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• 2017

Fumigation using chlorine dioxide ($ClO_2$) has been regarded as a potential control technique against stored grain insect pests. The control efficacy can be enhanced with increase of opening rates of spiracles by facilitating the toxic gas delivery to internal body. To test this hypothesis, this study used the Indianmeal moth, Plodia interpunctella, which was known to be susceptible to $ClO_2$, and analyzed the opening rate of spiracles. A total of 9 pairs of spiracles were observed in P. interpunctella larvae, in which one pair was located on the prothorax and eight pairs were on the abdomen. Within the body, the spiracles were connected to longitudinal and transverse tracheal trunks. The open spiracles were determined by the dye-infiltration method. Based on this method, the opening rate of spiracles increased up to about 60% with increase of ambient temperatures. Furthermore, exposure to carbon dioxide stimulated the opening rate of spiracles up to about 95%. In contrast, exposure to $ClO_2$ prevented the spiracle opening and resulted in only 25% of spiracles in an opening state. The addition of carbon dioxide to $ClO_2$ treatment rescued the opening rate of spiracles as much as the carbon dioxide single treatment. Based on this modulatory activity of carbon dioxide against spiracles, the combined treatment of $ClO_2$ with carbon dioxide resulted in significant increase of its toxicity against P. interpunctella compared to a single $ClO_2$ treatment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.59-69
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• 2018

In this paper, we present a robust beamforming design to tackle the weighted sum-rate maximization (WSRM) problem in a multicell multiple-input multiple-output (MIMO) - non-orthogonal multipleaccess (NOMA) downlink system for 5G wireless communications. This work consider the imperfectchannel state information (CSI) at the base station (BS) by adding uncertainties to channel estimation matrices as the worst-case model i.e., singular value uncertainty model (SVUM). With this observation, the WSRM problem is formulated subject to the transmit power constraints at the BS. The objective problem is known as on-deterministic polynomial (NP) problem which is difficult to solve. We propose an robust beam forming design which establishes on majorization minimization (MM) technique to find the optimal transmit beam forming matrix, as well as efficiently solve the objective problem. In addition, we also propose a joint user clustering and power allocation (JUCPA) algorithm in which the best user pair is selected as a cluster to attain a higher sum-rate. Extensive numerical results are provided to show that the proposed robust beamforming design together with the proposed JUCPA algorithm significantly increases the performance in term of sum-rate as compared with the existing NOMA schemes and the conventional orthogonal multiple access (OMA) scheme.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.15 no.2
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• pp.115-122
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• 2004

It is difficult to think of any behavioral process that is more intrinsically important to human beings than social attachment. Feeding, sleeping and locomotion are all necessary for survival, but humans are 'a social animal' and it is our social attachment that we live for. One of the early pioneers in this area, Harry Harlow, described the different behavioral processes that are involved in the formation of parent-infant, filial and pair(male-female) bonds. Each of these involves multi-sensory processing and complex motor responses. Over the past decades, studies in a range of vertebrates, including humans, have begun to address the neural basis of attachment at a molecular, cellular and systemic level. This review describes some of important insights from these works, involving three different areas：1) Neurobiological research of infant-parent, parent-infant attachment, 2) Animal studies regarding attachment, 3) Neurobehavioral studies of maltreatment/deprivation causing serious breakdown of attachment relationship in humans.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.70-77
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• 2009

In an RFID network consisting of a single reader and many tags, a framed and slotted ALOHA, which provides a number of slots for the tags to respond, was introduced for arbitrating a collision among tags' responses. In a framed and slotted ALOHA, the number of slots in each frame should be optimized to attain the maximal efficiency in tag cognizance. While such an optimization necessitates the knowledge about the number of tags, the reader hardly knows it. In this paper, we propose a tag cognizance scheme based on framed and slotted ALOHA, which is characterized by directly taking a Bayes action on the number of slots without estimating the number of tags separately. Specifically, a Bayes action is yielded by solving a decision problem which incorporates the prior distribution the number of tags, the observation on the number of slots in which no tag responds and the loss function reflecting the cognizance rate. Also, a Bayes action in each frame is supported by an evolution of prior distribution for the number of tags. From the simulation results, we observe that the pair of evolving prior distribution and Bayes action forms a robust scheme which attains a certain level of cognizance rate in spite of a high discrepancy between the Due and initially believed numbers of tags. Also, the proposed scheme is confirmed to be able to achieve higher cognizance completion probability than a scheme using classical estimate of the number of tags separately.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.9-14
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• 2009

The effects of post-annealing temperature on the optical and electrical properties of P-doped ZnO thin films grown on sapphire substrate have been investigated under oxygen ambient. The XRD shows that regardless of the post-annealing temperature, all P-doped ZnO thin films indicate the c-axis orientation. The results of hall effect measurements indicate the P-doped ZnO thin film annealed at $850^{\circ}C$ exhibits p-type behavior with hole concentration of $1.18{\times}1016cm^{-3}$ and hole mobility of $0.96cm^2/Vs$. The low-temperature (10K) Photoluminescence results reveal that the peak related to the neutral-acceptor exciton (A0X), free electrons to neutral acceptor (FA) and donor acceptor pair (DAP) at 3.351ev, 3.283eV and 3.201eV are observed in the films showing p-type behavior with acceptor. The optimization of deposition and post-annealing conditions will certainly make the P-doped ZnO thin films promising materials for the application to the next generation of optical devices.

• Journal of the Korean earth science society
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• v.25 no.8
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• pp.656-662
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• 2004

The purposes of this study was to analyze the knowledge sources and of high school students' responses on tasks in scientific context and tasks in everyday context, and was to investigate the relationship between the consistency of responses and cognitive style. One hundred fifteen students participated in study. The students were asked to solve ten paris of problems about several concepts of circulation of atmosphere and water. Each pair of the problems consisted of two questions which were about the same concept but were about different context. That is to say, one questions related to scientific context and the other related to everyday context. Every questions included one subquestion in other to investigate the students' sources of knowledge. The students' responses on two questions in each problem were analyzed in order to compare the sources of knowledge and examine the influence of task context. The results of the study can be summarized as follows: First, students' knowledge sources varied by task contexts. That is to say, the students selected 'Science activities in school' as main source in questions related scientific context and chose 'Experience in daily life' as main source in questions related to everyday context. Second, inconsistency score on all paris of problem was significantly higher than consistency score (p<.01). This result indicated students' responses were much dependent on context. third, field-dependent students were more dependent on context, considering higher inconsistency score than field-dependent ones.

• The Journal of Korean Academy of Sensory Integration
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• v.7 no.2
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• pp.13-22
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• 2009

Objective : The aim of this study is to verify the effects of group sensory integrative intervention for sensory motor ability, behaviors in children with developmental delay. Method : The subjects were five children with developmental delays aged between 3 and 5. All Children participated in 26 sessions of group sensory integrative intervention. Children' behavior during testing was observed to assess the sensory motor ability, behaviors, the clinical observation. One group pretest- posttest design was used to verify the effect of group sensory integrative intervention. The observed children' behavior during testing were tested by the Wilcoxon matched-pair signed rank test. Results : There is no significant difference in the clinical observation between pre and post intervention. However, subjects showed the significant difference in Social interaction(Z=-2.121, p=.034), Attention(Z=-2.032, p=.042), total score in Behavior during testing(Z=-2.032, p=.042). Conclusions : The result in this study suggested that the sensory integrative intervention is effective in facilitating the social skills and improving the attention and behaviors. On the other hand, there is no effect in sensory motor ability. It is difficult to generalize the conclusion because the number of the subject was limited and the environmental confounding factors has not been controlled. Therefore, it is needed to supplement these limitations in the future study.

• The Journal of Korean Academy of Sensory Integration
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• v.7 no.2
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• pp.1-12
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• 2009

Objective : The purpose of this study is to find out whether group approach of sensory integration (SI) enhances sensory processing, fine motor function, and social skill for the children with sensory integration disorders. Method : Three children with problems related in sensory integration had got received 21 intervention sessions. We evaluated children with sensory profile(SP), social maturity test, Korean-developmental test of visual perception(K-DTVP), Bruininks-Oseretsky Test of Motor Proficiency(BOTMP) before-and after intervention. The statistical significance of data is tested by the Wilcoxon matched-pair signed rank test. Results : All data of post-intervention did not show any statistically significant differences; SP, social maturity test, K-DTVP, BOTMP. Conclusions : This study is to verify the effect of group SI intervention on sensory processing, fine motor function, and social skill for children with sensory integration disabilities. The results were not statistically significant. However, the average score after SI intervention has been improved in the section of fine motor and social skill comparing to that of pre-intervention period. It would have positive impact for children with sensory integration disabilities. It is needed to study with the larger number of target children and more often treatment session are suggested. The confounding variables also should be controlled in the further study.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.673-684
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• 2003

A degenerated differential pair has been widely used as a standard topology for digitally programmable CMOS VGAs. A variable degeneration resistor has been implemented using a resistor string or R-2R ladder with MOSFET switches. However, in the VGAs using these conventional methods, low-voltage and high-speed operation is very hard to achieve due to the dc voltage drop over the degeneration resistor. To overcome this problem a new variable degeneration resistor is proposed where the dc voltage drop is almost removed. Using the proposed gain control scheme, a low-voltage and high-speed CMOS VGA is designed. HSPICE simulation results using a 0.25${\mu}{\textrm}{m}$ CMOS process parameters show that the designed VGA provides a 3dB bandwidth of 360MHz and a 80dB gain control range in 2dB step. Gain errors are less than 0.4dB at 200MHz and less than l.4dB at 300MHz. The designed circuit consumes 10.8mA from a 2.5V supply and its die area is 1190${\mu}{\textrm}{m}$${\times}$360${\mu}{\textrm}{m}$.