• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.1
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• pp.1-10
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• 2018

It is difficult to predict the early-age cracks of strain restrained concrete members due to environmentally sensitive parameters. A new method is proposed to predict the cracks by test of autogenous deformation and self-induced restrained stress of specimens which simulates early-age crack state by hydration heat of the'Wall-On-Foundation'members. For this purpose, thermal analysis of entire structure considering the environmental condition is performed at first, and the specimens are set up where hydration heat was electronically controlled according to the analysis results. By measuring free deformation and force to compensate the autogenous strain including relaxation, feasibility of cracks can be estimated. The proposed method can predict the occurrence of cracks better than the material test of the early age concrete which has large variance. The method of this study is particularly useful when it is used as a preliminary experiments to predict the crack more precisely before full-scale concrete placement in construction of large structures.

• Economic and Environmental Geology
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• v.17 no.3
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• pp.215-230
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• 1984

Petrological, paleomagnetic, geomorphological and structural studies on the southern part of, so called, Chugaryeong rift valley, have been carried out in order to clarify the nature of the rift valley. Three stages of volcanic activities characterized by Jijangbong acidic volcanic rocks and tholeiitic and andesitic basalt of Cretaceous age(?), and Jongok Quaternary olivine basalt occurred along the Dongducheon fault line. Jijangbong acidic volcanic rocks distributed in the central part of the studied area consist of rhyodacite, acidic tuff and tuff breccia, which are bounded by Dongsong fault on the east and Daegwangri fault on the west. The Jongok basalt differs from those of Ulrung and Jeju islands in mineralogy, chemical composition and differentiation. Jongok basalt distributed along the Hantan river dilineates the vesicles curved toward downstream direction and increment of numbers and thickness of lava flow toward upstream direction. These facts suggest that lava flowed from upstream side of the river. Rectangular drainage patterns also support the presence of the Dongducheon, Pocheon, Wangsukcheon and Kyonggang faults which were previously known. LANDSAT image, however, does not show any lineaments which could be counted as a graben or rift valley. Displacement of Precambrian quartzite and Jurassic Daedong supergroup along the southwestern extension of the Dongducheon fault shows the right lateral movement. The Paleomagnetic study of the tholeiitic and andesitic basalts from Baegeuri, Jangtanri and Tonghyeonri located at 2. 3km east, 0km east, and 1.5km west of Dongducheon fault respectively shows that their VGP(Virtual Geomagnetic Pole) being to intermediate geomagnetic field of short duration which suggests that they formed in almost same period. Mean VGP of Jongok basalt is located 82.4N and 80.6E. This is in good coincidence with worldwide VGP of Plio-Pleistocene indicating that Jongok basalt was extruded during Plio-Pleistocene epoch, and suggesting that the studied area has been tectonically stable since then. From the present study, the tectonic episode of the region is concluded as following three stages. 1. The 1st period is worked by the Daebo orogeny of Jurassic during which granodiorite was intruded in Precambrian basement. 2. The 2nd period is the time when right lateral strike-slip fault of NNE-SSW direction was formed probably during late Cretaceous to Paleogene and the Jijangbong acidic volcanic rocks and the older basalts were extruded. 3. The 3rd period is the time when the fault was rejuvenated during Pliocene or Pleistocene accompanied by the eruption of Jongok basalt. As a conclusion, geologic structure of the studied area is rather fault line valley than graben or rift valley, which is formed by differential erosion along the Dongducheon fault suggesting a continuation of the Sikhote-Alin fault. The volcanic rocks including the Jijangbong acidic rocks, tholeiitic-andesitic basalt and olivine basalt are associated with this fault line.

• Economic and Environmental Geology
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• v.25 no.1
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• pp.87-96
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• 1992

Paleomagnetic study on the sedimentary rocks in the Choongnam Coal Field has been carried out to determine the direction of declination and inclination of NRM and position of paleomagnetic pole, and to investigate the geotectonism and geomagnetic stratigraphy of the sedimentary rocks in the Daedong Group. As a result of paleomagnetic study, the study area can be divided tectonically into two blocks by Baegunsa fault, namely northwestern and southeastern blocks. Site mean declination and inclination of Baegunsa and Seoungjuri Formations in the northwestern block are $23.2^{\circ}$ and $54.9^{\circ}$, respectively. Those of Amisan, Jogyeri, Baegunsa and Seoungjuri Formations in the southeastern block show normal direction with declination and inclination of $-22.1^{\circ}$ and $11.2^{\circ}$, and reversed direction with those of $158.5^{\circ}$ and $-12.6^{\circ}$, respectively. Average paleomagnetic pole position in the northwestern block is located at $212.9^{\circ}E$ and $71.1^{\circ}N$, and that in the southeastern block at $345.7^{\circ}E$ and $53.3^{\circ}N$. This difference suggests relative rotation of about $45^{\circ}$ between two blocks. The paleolatitude of Daedong Group at the time of sedimentation is $5.6^{\circ}N$ much lower than present latitude of $37.7^{\circ}N$. Compared with worldwide Mesozoic paleomagnetic polarity stratigraphy, Amisan Formation is correlated with the lower boundary of Nuanetsi reversal zone in Graham interval, and Baegunsa and Seoungjuri Formations are correlated with just upper part of the upper boundary of Nuanetsi reversal zone, and their geologic ages are Late Triassic to Early Jurassic. The position of paleomagnetic pole acquired from Daedong Group in the study area is different from those in other places. This may be attributed to the different tectonic movement by Daebo Orogeny occurred after the deposition of Daedong Group.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.51-56
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• 2009

Safety and quality assessment systems are very important in manufacture, storage, transportation, and handling of hazardous materials(hazmat) to prevent hazmat disasters. At present, hazardous materials exist everywhere in our daily lives with various forms of plastics, household products of cleaning and washing detergents, fertilizers or petroleum-related products. However, hazardous materials are dangerous substances when they are released to human or environment. Hazardous materials become very widely used substances in the age of oil-based industrial economy. The Korean Ministry of Environment (KMOE) describes about one hundred thousand types of chemicals are produced and used worldwide. Over four hundred new chemicals are introduced in every year. A crucial question for the Korean hazardous material management may have been raised: Will you be safe from hazardous material incidents? The gas leak disaster at Union Carbide's Bhopal, India in 1984 that made over 6,400 people killed and 30,000 to 40,000 people seriously injured is the representative case for the safety of hazmat. Korea becomes vulnerable to hazmat disaster due to the development of high-tech industry. Thus, the risk assessment system is required to Korea for transferring abandoned hazmat management systems to self-correcting safety systems. This research analyzed characteristics of various hazmat incidents applying statistical analysis methods including frequency analysis or analysis of category data to hazmat incidents for ten years. All of three analyses of category data indicate the significance of causality between hazmat incident site groups and seasons, regional groups, and incident casualty groups.

• Journal of Life Science
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• v.25 no.5
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• pp.601-606
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• 2015

Hutchinson (1961) proposed that the large number of species in most plankton communities is remarkable in review of the competitive exclusion principle, which suggests that in homogeneous, well-mixed environments species that compete for the same resources cannot coexist. The principle of competitive exclusion would lead us to conclude that only a few species could coexist in such circumstances. Nevertheless, numerous competing species in most natural habitats are able to coexist, while generally only few resources (niches) limit these communities. It is coined “the paradox of plankton” by Hutchinson. We reviewed some literature of the proposed solutions and give a brief overview of the mechanisms proposed so far. The proposed mechanisms that we discuss mainly include spatial and temporal heterogeneity in physical and biological environment, externally imposed or self-generated spatial segregation, horizontal mesoscale turbulence of ocean characterized by coherent vortices, oscillation and chaos generated by several internal and external causes, stable coexistence and compensatory dynamic under fluctuating temperature in resource competition, and finally the role of toxin-producing phytoplankton in maintaining the coexistence and biodiversity of the overall plankton populations. Especially we sited Roy and Chattopadhyay’s reviews and their toxin-producing hypothesis by phytoplankton. This review may be some information to study plankton communities and effect to put the solutions to the paradox that have been proposed over the years into perspective.

• Journal of dental hygiene science
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• v.13 no.3
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• pp.230-237
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• 2013

In this research, the degree of depression and death orientation of the 332 female students majoring in dental hygiene at colleges located in Gyeongsangbuk-do Province were examined and analyzed through a structured self-administered questionnaire from May to July, 2012, for the purpose of improving their mental health. The results are as follows: 1. The degree of depression of the subject students majoring in dental hygiene was shown that 59.9%, 36.8%, 3.0%, and 0.3% of the students were in the normal group, mild depression group, moderate level of depression group, and severe depression group, respectively. 2. The grand mean and the standard deviation of the subjects'death orientation was $2.09{\pm}0.62$ points. 3. The degree of depression of the subjects whose family's economic level was low, whose satisfaction with their family background was low, whose satisfaction level with their major was low, whose school records was low, who frequently thought about death, and who attempted suicide was high in a meaningful way, and death orientation was meaningfully low. In addition, those in the group with the experience of feeling suicidal were proved to have a significantly high degree of depression, and those without the experience of education about death had a low level of death orientation. 4. The degree of depression and death orientation had a positive correlation. When the study results above are combined, follow-up research needs to be conducted so that differentiated programs linked with the care for mental health for the formation of proper attitudes toward depression and death will be established to help students lead a positive life.

• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.615-625
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• 2015

This study examined the effects of wildlife or wildlife species on national park visitors' perception of place attributes and recreational experiences. Data were collected from 502 users of Seongsamjae Rest area and Nogodan Shelter area in Jirisan National Park and 173 college students during May-June 2014 using survey questionnaire. Some simulated photographs of water deer and Asiatic black bears were used for the college student survey. Overall, awareness about wildlife inhabiting in Jirisan National Park (AW) was not related with one's perception of place attributes (PPA) (i.e., crowdedness, naturalness, safety) and types of visitors' recreational experiences. Respondents with higher awareness about the presence of Asiatic black bear (AABB), however, tended to perceive Jirisan National Park as a place that provides 'wild' or 'natural' recreational opportunities compared to those with lower AABB. Differences in PPA (i.e., crowdedness, naturalness, safety) and types of recreational experiences were also found to be influenced by wildlife species. Respondents exposed to bear or water deer tended to perceive their recreational experiences as more 'wild'. Existence of wildlife in Jirisan National Park had a positive effect on the quality of visitors' recreational experiences. Different wildlife species showed different levels of effectiveness to quality enhancement of recreational experience. Some practical implications of the study were discussed from a managerial point of view.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.1
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• pp.123-132
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• 1999

In this paper, a quadratic sigmoid neural equalizer(QSNE) is proposed to improve the performance of conventional neural equalizer in terms of bit error probability by using a quadratic sigmoid function as the activation function of neural networks. Conventional neural equalizers which have been used to compensate for nonlinear distortions adopt the sigmoid function. In the case of sigmoid neural equalizer, each neuron has one linear decision boundary. So many neurons are required when the neural equalizer has to separate complicated structure. But in case of the proposed QSNF and quadratic sigmoid neural decision feedback equalizer(QSNDFE), each neuron separates decision region with two parallel lines. Therefore, QSNE and QSNDFE have better performance and simpler structure than the conventional neural equalizers in terms of bit error probability. When the proposed QSNDFE is applied to communication systems and digital magnetic recording systems, it is an improvement of approximately 1.5dB~8.3dB in signal to moise ratio(SNR) over the conventional decision feedback equalizer(DEF) and neural decision feedback equalizer(NDFE). As intersymbol interference(ISI) and nonlinear distortions become severer, QSNDFE shows astounding SNR shows astounding SNR performance gain over the conventional equalizers in the same bit error probability.

• Journal of Environmental Policy
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• v.8 no.4
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• pp.75-94
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• 2009

The process of obtaining third-party financing contacts was analyzed via a two-stage game model: a "signaling game" for the first stage,and a "principal-agent model" for the second stage. The two-stage game was solved by a process of backward induction. In the second stage game, the optimal effort level of the energy saving company (ESCO), the optimal compensation scheme of the energy user, and the optimal payoffs for both parties were derived for each subgame. The optimal solutions forthe different subgames were then compared with each other. Our main finding was that if there is some restriction on ESCO's revenue (e.g. a progressive sales tax) that causes ESCO's revenue toincrease at a decreasing rate, then the optimal sharing ratio is uniquely determined at a level of strictly less than one under a linear compensation scheme, i.e. a unique balance exists. Subgames have a unique equilibrium arrived at separately for each situation,. Within this equilibrium, energy users accept energy audit proposals from H-type ESCOs with high levels of technology, but reject proposals from L-type ESCOs with low levels of technology. While L-type ESCOs cannot attain profits in the third-party financing market, H-type ESCOS can pocket the price differential between L-type and H-type audit fees. Accordingly, revenues in an H-type ESCO equilibrium increase not only in line with the technology of the ESCO inquestion, but also faster than in an L-type equilibrium due to more advanced technology. At the same time, energy users receive some positive payoff by allowing ESCOs to perform third-party financing tasks within their existing energy system without incurring any extra costs.

• Journal of Korean Home Economics Education Association
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• v.16 no.2
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• pp.55-72
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• 2004

The Purpose of this study was to investigate the influences of the teacher-directed and the learner-directed ICT used instruction on learning achievement of home economics and resource management behavior according to the learning ability of students and resource management behavior of a mother. The subjects of this study were middle school students, who was divided into three groups traditional instruction group, teacher-directed ICT used instruction group, and learner-directed ICT used instruction group. This study was carried out the experimental instruction. After experimental instruction, the learning achievement and resource management behavior was estimated by test sheets. The data were processed with two-way ANCOVA and Scheffe test for post-hoc analysis The results of study were as follows : First, there was no significant difference in the influences of the ICT used instruction on learning achievement of home economics according to the learning ability. Second, there was significant difference in the influences of the ICT used instruction on learning achievement of home economics according to the resource management behavior of a mother. Third, there was no significant difference in the influences of the ICT used instruction on the resource management behavior according to the learning ability. Fourth, there was no significant difference in the influences of the ICT used instruction on the resource management behavior of a student according to the resource management behavior of a mother.