• Phonetics and Speech Sciences
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• v.12 no.3
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• pp.33-40
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• 2020

The purpose of this research was to find out the relation between Korean learners' English proficiency and the ratio of the length of the stressed vowel in a monosyllabic noun to that of the unstressed vowel in an article of the noun phrases (e.g., "a cup", "the bus", etcs.). Generally, the vowels in monosyllabic content words are phonetically more prominent than the ones in monosyllabic function words as the former have phrasal stress, making the vowels in content words longer in length, higher in pitch, and louder in amplitude. This study, based on the speech samples from Korean-Spoken English Corpus (K-SEC) and Rated Korean-Spoken English Corpus (Rated K-SEC), examined 879 English noun phrases, which are composed of an article and a monosyllabic noun, from sentences which are rated on 4 levels of proficiency. The lengths of the vowels in these 879 target NPs were measured and the ratio of the vowel lengths in nouns to those in articles was calculated. It turned out that the higher the proficiency level, the greater the mean ratio of the vowels in nouns to the vowels in articles, confirming the research's hypothesis. This research thus concluded that for the Korean English learners, the higher the English proficiency level, the better they could produce the stressed and unstressed vowels with more conspicuous length differences between them.

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.410-419
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• 2005

Community structure of evergreen broad-leaved forest of Mt. Yeogwi in Jin-do was investigated to secure sustainable conservation of evergreen broad-leaved forest. Twenty survey plots of $20m{\times}20m$ were established along the elevation from 200 m to 390 m above the sea level in the northwestern slope. The woody species were tallied at each plots. DBH distribution of the major evergreen broad-leaved trees was investigated to find out the spatial distribution. Cluster analysis was applied to a set of vegetation data, that is, importance value to classify the forest community. Species diversity, evenness and species correlation were analysed. Canonical correspondence analysis was also applied to vegetation data and soil environmental data. Cluster analysis showed that the forests of Mt. Yeogwi were classified into 2 community groups, such as Camellia japonica community group and Quercus acuta community group. C japonica community group was subdivided into C japonica- evergreen broad-leaved trees community, C. japonica-Neolitsea sericea community, and C. japonica-deciduous broad-leaved trees community. Q. acuta community group was subdivided into Q. acuta-C. japonica community, and Q. acuta community. C. japonica, Q. acuta, N. sericea, Machilus thunbergii and Illicium religiosum were dominant evergreen broad-leaved tree species, while Styrax japonica, Lindera erythrocarpa, Cornus kousa, Prunus sargentii, Albizzia julibrisin and Quercus acutissima were major deciduous tree species. Species diversity was greater in Q. acuta community group (0.8231 for Q. acuta-C. japonica community, and 0.8135 for Q. acuta community) than in C. japonica community group (0.7674 for C. japonica-evergreen broad-leaved trees community, 0.6164 for C. japonica-N. sericea community, and 0.7931 for C. japonica-deciduous broad-leaved trees community). DBH 2 cm~10 cm of major evergreen broad-leaved trees occupied 80% of all. C. japonica of less than DBH 5 cm tended to aggregate but distribute randomly or regularly with increasing DBH. Q. acuta distributed more aggregately than C. japonica and Machilus thunbergii for more than 15 cm of DBH. C. japonica correlated negatively with Q. acuta, I. religiosum and C. kousa, but positively with N. sericea. with significance at 1% level. Q. acuta correlated negatively with C. japonica, N. sericea and M. thunbergii but positively with l. religiosum. There were also negative correlation between N. sericea and C. kousa. CCA showed that forest communities were correlated with soil variables such as CEC, soil organic matter and soil pH. With increased soil organic matter and CEC, and decreased soil pH, C. japonica was dominant and forest community and Q. acuta and N. sericea tended to develop in the evergreen broad-leaved forest.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.226-226
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• 2008

지난 10여년 동안 Sn-3.0Ag-0.5(wt%)Cu 합금은 대표 무연솔더 조성으로 다양한 전자제품의 실장 및 접합에 적용되어 왔으며, 그 신뢰성 역시 충분히 검증된 바 있다. 그러나 최근 Ag 가격의 급격한 상승과 솔더 접합부의 내 충격 신뢰성을 보다 향상시키고자 하는 업계의 동향은 Ag의 함량이 낮은 무연솔더 조성의 적용 확대를 유도하고 있다. 이에 따라 본 연구자들은 저 Ag 함유 무연슬더로 Sn-1.2Ag-0.5Cu-0.4In 조성을 제안한 바 있는데, 이는 Sn-3.0Ag-0.5Cu 조성 이상의 solderability를 가지면서도 그 금속원료 가격이 약 20% 가량 저렴한 특징을 가진다. 또한 열 싸이클링 (cycling) 테스트를 통한 슬더 조인트의 신뢰성을 평가한 결과, Sn-3.0Ag-0.5Cu에 크게 뒤떨어지지 않는 양호한 특성이 관찰되었다. 따라서 본 연구에서는 열 싸이클링 테스트와 더불어 최근 그 중요성이 지속적으로 커지고 있는 내 충격 신뢰성 평가 시험을 실시하여 개발된 4원계 무연솔더 조성의 기계적 특성을 기존 무연솔더 조성과 비교, 분석해 보았다. 각 솔더 조성은 솔더 볼 형태로 제조되어 CSP(Chip Scale Package) 상에 범핑 (bumping)되었으며, CSP를 PCB(Printed Circuit Board) 상에 실장하는 공정에서도 Sn-3.0Ag-0.5Cu 및 Sn-1.2Ag-0.5Cu-0.4In의 두 종류의 솔더 페이스트가 사용되었다. 본 연구에서의 내 충격 신뢰성 시험에는 자체 제작한 rod drop 시험기를 사용하였는데, 고정된 CSP 실장 board의 후면 부위를 일정한 높이에서 추를 반복적으로 자유 낙하시켜 급격한 충격을 주는 방식으로 실험을 실시하였다. 이 때 추의 무게는 30g, 낙하 높이는 10cm 였으며, 추의 낙하 시 측정된 board 의 휨 변위량은 약 0.7mm로 측정되었다. 사용된 CSP와 PCB 는 모두 daisy chain 방식으로 연결되어 있기 때문에 저항측정기를 사용한 간단한 실시간 저항 측정 방법으로 시험 이력에 따른 파단부의 발생 시점과 대략의 위치를 손쉽게 확인할 수 있었다. 솔더 조인트의 파단 기준 저항값으로 $1000\Omega$을 설정하였으며. 각 조건 당 5 개 이상의 샘플에 대해 평가를 실시한 후 그 평균값을 조사하였다. 시험 결과 제안된 Sn-1.2Ag-0.5Cu-0.4In 조성은 대표적인 저 Ag 함유 조성인 Sn-1.0Ag-0.5Cu에 비해서는 떨어지는 내 충격 신뢰성을 나타내었지만, 우수한 연성에 기인하여 Sn-3.0Ag-0.5Cu 조성에 비해서는 약 2 배 이상 우수한 신뢰성이 관찰되었다. 또한 CSP의 실장 시 Sn-3.0Ag-0.5Cu보다 Sn-1.2Ag-0.5Cu-0.4In 조성 솔더 페이스트를 적용한 경우에서 보다 우수한 내 충격 신뢰성을 나타내어 기본적으로 개발된 Sn-1.2Ag-0.5Cu-0.4In 솔더 페이스트가 Sn-3.0Ag-0.5Cu 조성의 기존 솔더 페이스트 보다 내 충격 신뢰성이 우수함을 검증할 수 있었다. 각 조성의 솔더 조인트를 $150^{\circ}C$ 에서 500시간 aging한 후 실시한 내 충격 신뢰성 평가에서는 모든 조성에서 그 신뢰성이 급감하는 경항을 나타내었으나, Sn-1.2Ag-0.5Cu-0.4In가 Sn-l.0Ag-0.5Cu보다도 그 상대적인 신뢰성이 우수한 것으로 관찰되었다. 이와 같이 aging 후 실시하는 충격시험은 가장 실제적인 상황과 유사한 조건이므로 상기의 실험 결과는 매우 고무적이었으며, 이에 대한 보다 면밀한 분석이 요청되었다. 마지막으로 파면 및 미세조직 관찰을 통하여 각 조성에서의 충격 파단 특성을 비교, 분석해 보았다.

• Korean Journal of Environment and Ecology
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• v.28 no.6
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• pp.751-761
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• 2014

This study was carried out to analyze the vegetation properties, soil characteristics and ordination of Rhododendron brachycarpum population in South Korea. Rhododendron brachycarpum were mainly distributed along the Ulleungdo and Baekdudaegan of the Korean penninsula and it's population was located at an elevation of 872m to 1466m. The Rhododendron brachycarpum population was classified into Taxus cuspidata var. latifolia dominant population, Magnolia sieboldii dominant population, Thuja koraiensis dominant population and Rhododendron brachycarpum typical population. The composition of soil properties in the same areas are as follows: organic matter, total nitrogen, available phosphorous, exchangeable $K^+$, exchangeable $Ca^{2+}$, exchangeable $Mg^{2+}$ contained, and soil pH. The capacities of these chemical properties of the soil ranged from 10.45~15.28%, 0.37~0.61%, $0.21{\sim}0.35cmol^+/kg$, $0.39{\sim}2.54cmol^+/kg$, $0.17{\sim}0.50cmol^+/kg$, $18.28{\sim}22.81cmol^+/kg$ and 4.66~5.23 respectively. The results of the correlation between communities and soil conditions of vegetation of Rhododendron brachycarpum by DCCA ordination method are as follows: Taxus cuspidata var. latifolia dominant population was found in the very steep sloped area that has low percentage of total organic matter and nitrogen than other populations. Magnolia sieboldii dominant population and Thuja koraiensis dominant population was found in the steep sloped area that has high percentage of total organic matter and nitrogen than other populations. Thuja koraiensis dominant population was found in the gentle sloped area that has high percentage of altitudinal and rock exposure. Current status of Rhododendron brachycarpum is very vulnerable with a collection of herbs constantly threatening the species' survival. Thus, concrete conservation plans to protect natural habitats should be set up as soon as possible.

• Korean journal of applied entomology
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• v.24 no.3 s.64
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• pp.117-121
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• 1985

Through the laboratory and vinyl house experiments, the effects of inoculum density, plant age and temperature on the incidence of Phytophthora crown rot of pepper (Capsicum annum L.) were investigated. The propagule survival was greater in the natural soil than in autoclaved soil within first 2 weeks when the sporangial suspension of the pathogenic fungus was incorporated into soil, thereafter the survivability reduced rapidly. The propagule was not detectable in 35 days by means of Papavizas selective medium neither in natural nor in autoclaved soil. At least 5 sporangia per gram soil were required to induce crown rot for 30 days old pepper seedlings. Further increase in inoculum concentration above this threshold level resulted in higher disease incidence and shorter incubation period. When the same amount of inoculum was infested, higher disease incidence was observed for younger plants until 3 weeks after inoculation. On the other hand after 4 weeks this tendency was not extended any more. Younger plants were recognized as having shorter incubation period upon infection, however, the days from first symptom appearance to complete death were not significantly different among differently aged seedlings. Exposure of inoculated pepper seedlings to $25^{\circ}C$ resulted in highest infection rates and followed by those to $30^{\circ}C\;and\;20^{\circ}C$ but no disease was found at $15^{\circ}C\;and\;35^{\circ}C$ for 10 days. When the plants previously incubated at different temperature for 10 days were moved to $25^{\circ}C$ room temperature, prior exposure to $20^{\circ}C\;and\;30^{\circ}C$ brought continuous disease development. Even those plants preincubated at $15^{\circ}C$ were diseased up to 50%. But the prior exposure to $35^{\circ}C$ induced no symptom developed, indicating no seedlings infected at all.

• Food Science and Preservation
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• v.24 no.8
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• pp.1149-1157
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• 2017

Inflammation is the first response of the immune system to infection or irritation in our body. The use of medicinal plants has been widely applied as an alternative source for drug development. One of marine natural resources, the anti-inflammatory effect of Ishige sinicola ethanol extract (ISEE), was evaluated by using LPS-induced RAW 264.7 cell and mice model. As a result, the production of nitric oxide (NO) and pro-inflammatory cytokines (IL-6, IL-$1{\beta}$, TNF-${\alpha}$) were inhibited with increasing concentration of ISEE without any cytotoxicity. Furthermore, ISEE suppressed the expression of not only inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor-kappa B (NF-${\kappa}B$) p65, and mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated kinase (ERK) 1/2, p38, and c-Jun N-terminal kinase (JNK) in a dose-dependent manner. In mice ear edema test, the formation of edema was reduced at the highest dosage of ISEE and the reduction of the number of infiltrated mast cells was observed in histological analysis. These results indicate that ISEE has a potent anti-inflammatory activity and can be used as a pharmaceutical material for many kinds of inflammatory disease.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2002.11a
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• pp.29-30
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• 2002

The goal of this research was to develop the effectiveness of in vitro culture method for A. formosanus and study the environment in vitro conditions affecting on growth. The first series of experiments were examined to investigate the response of three different basal media, MS (Murashige and Skoog, 1962), Knudson (KC; Knudson, 1946) and modified hyponex on growth and multiplication during in vitro culture. Multiple shoot proliferation was induced in shoot tip explants on Hyponex (H3) media supplemented with BA (1 mg1$\^$-1/) or TDZ (1-2 mg1$\^$-1/). Addition of activated charcoal (1%) to the TDZ containing medium promoted rapid shoot tip proliferation (11.1 shoots per explant) but the same medium had an opposite effect resulting in poor proliferation in the nodal explants. However, the regenerated shoots had slow growth rate and failed to elongate. This problem was overcome by transferring the shoot clumps to a hormone free H3 media supplemented with 2% sucrose and 0.5% activated charcoal. Using bioreactor culture for scaling up was also shown the best way for multiple shoot induction and growth of this plant. The second series of experiments was studied to investigate the effect of physical environment factors on growth of in vitro plantlets. The Anoectochilus formosanus plantlets were cultured under different air exchange rate (0.1, 0.9, 1.2h$\^$-1/), without sucrose or supplement 20g.1$\^$-1/ (photoautotrophic or photomixotrophic, respectively), and different photosynthesis photon flux (40, 80, 120 ,${\mu}$mol.m$^2$.s$\^$-1/- PPF). Under non-enrichment CO$_2$ treatment, slow growth was observed in photoautotrophical condition as compared with photomixotrophical condition on shoot height, fresh weigh and dry weight parameters; High air exchange (1.2.h-l) was found to be inadequate for plant growth in photomixotrophical condition. On the contrary, under CO$_2$, enrichment treatment, the plant growth parameters were sharply (visibly) improved on photoautotrophic treatments, especially on the treatment with air exchange rate of 0.9.h-1. The growth of plant in photoautotrophic condition was not inferior compared with photomixotrophic, and the best growth of plantlet was observed in treatment with low air exchange rate (0.9.h-1). Raising the PPF level from 80 to 120${\mu}$mol.m$\^$-2/.s$\^$-1/ decreased the plant height, particularly at 120${\mu}$mol.m$\^$-2/.s$\^$-1/ in photoautotrophic condition, fresh weight and dry weight declined noticeably. At the PPF of 120${\mu}$mol.m$\^$-2/,s$\^$-1/, chlorophyll contents lowed compared to those grown under low PPF but time courses of net photosynthesis rate was decreased noticeably. Light quality mainly affected morphological variables, changes of light quality also positively affected biomass production via changes in leaf area, stem elongation, chlorophyll content. Plant biomass was reduced when A. formosanus were grown under red LEDs in the absence of blue wavelengths compare to plants grown under supplemental blue light or under fluorescent light. Stem elongation was observed under red and blue light in the present experiment. Smaller leaf area has found under blue light than with other lighting treatments. Chlorophyll degradation was more pronounced in red and blue light compared with white light or red plus blue light which consequent affected the photosynthetic capacity of the plant. The third series of experiment were studied to investigate the effect of physical environment factors on growth of ex vitro plants including photosynthesis photon flux (PPF), light quality, growing substrates, electrical conductivity (EC) and humidity conditions. In the present experiments, response of plant on PPF and light quality was similar in vitro plants under photosynthesis photon flux 40${\mu}$mol.m,$\^$-2/.s$\^$-1/ and white light or blue plus red lights were the best growth. Substrates testing results were indicated cocopeat or peat moss were good substrates for A. formosanus growth under the greenhouse conditions. In case of A. formosanus plants, EC is generally maintained in the range 0.7 to 1.5 dS.m-1 was shown best results in growth of this plant. Keeping high humidity over 70% under low radiation enhanced growth rate and mass production.

• Clean Technology
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• v.18 no.4
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• pp.390-397
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• 2012

Removal characteristics of lead-contaminated soil at the military shooting range located in the Changwon city were studied experimentally using soil washing process. As a washing solution, hydrogen chloride (HCl) concentrations of 0.001, 0.01, 0.1 and 0.2 N were used, and soil : solution ratios were 1 : 2, 1 : 3, 1 : 4, and 1 : 5. Particle diameter of contaminated soil of 4-0.075 mm, and washing period of 5, 10, 15, 20, 30, 60, and 120 min were used as operating parameters. The optimum concentration of HCl solution was 0.1 N (56.3% of Pb removal efficiency) with 15 minutes operation period in views of economics, and the optimum soil : solution ratio was determined as 1 g : 3 mL for 69.7% of Pb removal efficiency with 0.1 N HCl and 15 minutes washing period. As washing period increased, removal efficiency was increased until 20 min of the removal efficiency of 75.3%, and then almost stable. Pb removal efficiency in soil particle diameters of 0.075 mm or more was ranged from 77.0% to 82.0%, but it was decreased to 52.8% in diameter of less than 0.075 mm. Therefore, the optimum cut-off size of the soil particle diameter was found less than 0.075 mm. Combined HCl solution and ultrasonic washing method showed better removal efficiency compared to only water or HCl washing method for particle sizes above 0.075 mm.

• Tuberculosis and Respiratory Diseases
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• v.48 no.1
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• pp.33-44
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• 2000

Background: To evaluate airway responses and inflammation to antigen in Sprague-Dawley rat asthma model, we examined airway responses, serial histologic changes of the lung, and the relationship between airway responses and airway inflammation after antigen airway challenge. Methods: Sprague-Dawley rats were sensitized with subcutaneous injection of 10 ${\mu}g$ ovalbumin(OA). Antigen airway challenges were done 14~16 days after sensitization and the sensitized rats were sacrificed 1h($A_E$), 6~8h($A_L$) and 1day($A_D$) after airway challenge, to examine the histologic changes of the lung. Airway responses were measured by body plethysmograph and recorded by enhanced pause(Penh) as an index of airway obstruction 6~8h after antigen challenges. Nonsensitized controls(10 rats) were also challenged with antigen and sacrificed 1 day later. Histopathologic examination of two trachea, large bronchi, small bronchi, and vessels was performed to evaluate the severity of inflammation and eosinophilic infiltration with H&E stain. Results: In 17 of 20 rats(85%) in both groups, we observed airway responses. Among them, an early response(ER) in 15 rats(75%), an dual response in 5(25%), and an late response(LR) only in 2 rats(10%) displayed. There were no significant differences in the severity of inflammation among the trachea, large bronchi, small bronchi and vessels in all groups after antigen challenge(p>0.05) and between early and late responders. The significant eosinophil infiltration was observed in 5 rats(50%) of AL(p<0.05) compared with in AE and controls. Also, eosinophil infiltration was observed in higher trend in LR(57.1%) compared to ER(40%)(p>0.05). Conclusion: Sprague-Dawley rats sensitized with subcutaneous injection of OA showed a significant airway responses to antigen challenge. But antigen challenges caused a little eosinophil infiltration and no significant airway inflammation. Asthma model of Sprague-Dawley rats could be useful for antigen-induced airway responses, but this model has a limitation for the study of human asthma because of no significant pathologic change.

• Food Science and Preservation
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• v.24 no.1
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• pp.27-35
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• 2017

Microbiological, physicochemical, and organoleptic properties of fresh-cut vegetables (FVs), carrots, green peppers, cherry tomatoes, and paprika after X-ray irradiation were evaluated to verify food quality suitable for the immune-depressed patients. Total concentrations of aerobic bacteria in non-irradiated samples, except for cherry tomatoes, were 1.63-3.34 log CFU/g. Irradiation dose exceed 0.4 kGy was used for carrots and green peppers whereas the sterilization dose of 0.2 kGy was used for both cherry tomatoes and paprika. A dose of 0.4 kGy was tentatively determined as the minimum allowable dose for sterilization of the FVs, based on $D_{10}$-values of X-ray irradiation (0.11-0.32 kGy) for Escherichia coli, Listeria monocytogenes, and Salmonella Typhimurium inoculated on the samples. With respect to the physiological properties, only hardness was significantly decreased as the absorbed dose increased; however, there were no significant differences in hardness of the sterilized samples using X-rays at 0.4 kGy compared with those of non-irradiated samples (p<0.05). Moreover, overall acceptance scores of the sterilized FVs were higher than 5.0 points on a 7-point scale, indicating a good organoleptic quality. In a survey on preference of hospitalized patients with cancer (n=50), the average scores for the sterilized FVs, except for carrots, were higher than 4.0 points. In conclusion, it is considered that the FVs, except for carrots, sterilized using X-rays at 0.4 kGy could be served to immune-depressed patients as hygienically safe foods with acceptable organoleptic properties.