• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.233-236
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• 2001

일반적으로 스피커를 동작시키게 되면, 스피커 보이스 코일에 열이 발생하게 되고, 열에 의한 보이스코일의 저항의 증가가 나타나게 되는데, 기존의 연구는 저음용 스피커(Woofer) 만을 대상으로 스피커의 음향특성 변화들에 관해 수행되었다. 그러나, 현대의 스피커는 A/V시스템분야의 발전에 따라 고음재생의 충실도가 강조되고 있는 경향이므로, 고음용 스피커(Tweeter)에 대한 열 발생의 영향을 조사하였다. 본 연구에서는 고음용 스피커의 입력전력에 따른 특성 변화를 조사하고, 입력전력의 증가로 인한 보이스코일(voice coil)의 저항 증가에 따른 고음용 스피커의 특성변화에 관해 실험하였다. 그리고, 스피커의 진동에 의한 펌프(pump) 역할을 이용하는 냉각용 구멍을 뚫어 스피커의 특성변화를 검토하였다. 실험대상으로는 직경 25mm의 돔(Dome)형 진동판을 가진 고음용 스피커와 이 스피커의 후면 중심부에 구멍을 뚫어 열 방출구가 형성된 3종의 시료를 대상으로 특성변화를 비교$\cdot$측정하였다. 여기에서, 사용된 시료는 국내 Y사의 판매용 고음용 스피커로 제품의 원 상태인, 구멍이 없는 것을 기준시료로 하고, 이와 동일한 제품들의 후면에 각각 직경 5mm, 10mm, 15mm의 구멍을 가공하여 비교시료로 하였다. 기준 및 비교시료의 스피커 특성을, 한국산업규격 KS C 6027의 측정법에 따라, 입력 1W 상태에서 기준시료의 사양을 측정하였고[1], 입력을 0.5W, 1W, 2W, 4W, 8W, 16W로 가하여, 시료별 입력증가에 따른 스피커의 주파수 응답특성, 임피던스(Impedance), 조화 왜(Harmonic Distortion)의 변화율 측정을 통해 스피커의 특성변화 정도를 검토하였다. 향후, 본 연구의 결과는 고음용 스피커의 특성 열화에 대한 예측 및 개선 방안을 제시하는 기본 자료로 활용이 가능할 것으로 사료된다.용하여 현금흐름예측을 할 수 있는 Model을 제시하였다. 특히 건설공사의 현금흐름 예측의 중요한 요소인 Cash-Out에 대하여, 공사비 구성요소인 자재, 노무, 중기, 외주, 경비등 각 Resource의 보할(Weights)을 실 공사원가에 따른 보할의 변화와 Resource들의 Time Lag를 적용 기존 연구자의 Model과 다른 Model을 제시하였다. 또한 기존 연구자들의 Model과 비교하여 편리성, 정확도 및 신뢰성이 높은 Model임도 증명하였다.세대까지도 발현수준이 유지될 것으로 판단된다. 이러한 연구결과는 계통으로 확립된 형질전환 동물에 부여된 새로운 유전형질은 지속적으로 후대로 유전될 수 있음을 제시한다.잖⨀瘀Ā퀇Āゑ잖⨀Ā퀇Ԁ￿™잖⨀䌀Ā퀇ĀꄏĀꀏꄏĀꀏ₱?⨀Ā Ԁ￿䂱?⨀ऀĀ耀Ā삱?⨀؀Ā Ā?⨀ጀĀ耀Ā?돀ꢘ?⨀硩?⨀ႎ?⨀?⨀넆돐쁖잖⨀쁖잖⨀／ࠐ?⨀焆덐瀆倆Āⶇ퍟ⶇ퍟ĀĀĀĀ磀鲕좗?⨀肤?⨀⁅Ⴅ?⨀쀃잖⨀䣙熸ጁ↏?⨀

• Journal of Korean Society of Forest Science
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• v.69 no.1
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• pp.51-55
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• 1985

Pinus thunbergii ${\times}$ P. massoniana $F_1$ hybrids were made by pollinating 15 years old Japanese black pine (P. thunbergii) with Masson pine (P. massoniana) pollen, air-shipped from Taiwan. The crossability between two species were observed. Seedling height, morphological characteristics, and the composition of phenolic compounds of these hybrids and the open-pollinated progenies of P. thunbergii were investigated. The results of the observation were as follows; 1) Number of the hybrid seeds per cone was 2.3, while open-pollinated Japanese black pine produced 26 seeds per cone. 2) All hybrid seedlings outgrew P. thunbergii, averaging 151% of mean height of Japanese black pine seedlings. The growth of hybrids was much variable, ranging from 120% to 208% of mean height of the open-pollinated progenies of P. thunbergii. 3) With regard to needle characteristics, the hybrid needles were longer and softer than those of P. thunbergii. The color of hybrid needles showed yellowish green. The positions of resin ducts in P. thunbergii observed medial, while those of hybrids showed medial and external. 4) No large difference in phenolic compound composition between hybrid and P. thunbergii was found, but phenolic compound of unknown 4 and 6 were observed only in hybrid. Further intensive work is recommended in this area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.310-315
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• 2012

The vegetable perilla is proved to be a late-maturing plant that flowers at the early of Oct. regardless of sowing time, so that the sowing time for seed production should be decided under consideration of maturity before beginning of frost. This experiment was carried out to determine the sowing date for seed production at greenhouse on late-maturing perilla cultivar, 'Ipdlkkae 1' in the middle region of Korea. The sowing dates were 8 times from May 6 to July 15 with an intervals of 10 days. As sowing date was delayed, the stem height, no. of nodes, no. of branches, no. of cluster per plant and no. of capsules per cluster were decreased. But as sowing was early, the lodging was occurred because of heavier growing. Days to flowering was linearly decreased about 0.86 day as affected by a day's delayed. But days from flowering to maturing was not significantly affected by sowing date. The grain yield was not significantly different among sowing from May 6 to June 15 and rapidly decreased the sowing after June 25 because of the reductions of no. of cluster and percent of ripened grain. Considering accumulative temperature, lodging, germination rate and grain yield, it is suggested that the sowing for seed production in late-maturing perilla cultivar should be finish before June 15 (transplanted at July 15) at greenhouse in the middle region of Korea.

• Journal of Science of Art and Design
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• v.9
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• pp.25-47
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• 2006

Amongst various methods of interpreting art, a understanding of the intention of artistic creation has been traditionally considered the most essential. Hermeneutics is the typical way of approaching it. With a focus on interpretation and understanding of the object, Hermeneutics delves into methodological techniques of interpretation and understanding of the existence of art from ancient Greece to the present. Nevertheless, from the Hermeneutic viewpoint, art as the object of interpretation is not free from social conditions and tradition; for this reason, interpretation of art basically has a socio-historical aspect. The starting point of this thesis is to examine the methods of understanding art from the socio-historical viewpoint. For this purpose, I study the theory of Hermeneutics as a basic of socio-historical interpretation of art, calling for methodology I need to justify inter-dependency of the epistemological viewpoint aid the ontological viewpoint in interpretation of art. Here, I suggest 'imputation(Zurechung)' and 'cycle(Zirkel)' as methodological concepts to support interdependency of these two viewpoints in Hermeneutics. Zurechung means explanation of meaning based upon the higher standard that includes to object of interpretation, while Zirkel means perception of part in order to understand the whole and, in turn, recognition of the whole in order to understand the part. These two concepts function inter-dependently in clarifying the object of interpretation and various problems of understanding human beings derived from it in the process of interpretation. This is also a key to the explanation that the object in social condition is closely related to historical perspective.

• Korean Journal of Weed Science
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• v.16 no.4
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• pp.301-308
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• 1996

In this study, a propagation characteristics of green kyllinga(Kyllinga brevifolia var. leiolepsis H.) was investigated. Two to three rhizomes(1st rhizome) arised from the basal part of main shoot at 4th leaf stage and were grown to extend on the soil surface. Then new shoots(lst tillers) emerged from every node of the 1st rhizome. Second rhizomes also arised from the basal part of lst tiller at the time of 4th leaf openning. With such a regularity, 5th rhizomes and about 688 shoots were produced from one plant during one year-cultivation without competition under the natural condition. The degree of vegetative growth and seed formation was 3 times and 2.5 times higher in rhizomeoriginated plant than in that from seed, respectively. The amount of seed formation and the 1000 seeds weight was highest in one planted on June 1 and Aug. 1, respectively. Short-day treatment of less than 14hr appeared to be necessary for the induction of flowering and it was effective as treated not during germination but since at least 2 leaf stage of green kyllinga. Each shoot individually responded to short-day. When plants were exposed to short-day (9hr, day / 15hr, night) treatment at the stage of 2-3 leaves, more than 7 cycles were required for flowering induction. Bolting in main shoot occurred after emergence of 4 leaves under the short-day condition. Exogenous $GA_3$ slightly accelerated the velocity of bolting only in short-day condition.

• Korean Security Journal
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• no.17
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• pp.143-155
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• 2008

Purpose of this study is to analyze actual perception of security business of security workers centering on employees working within building and to improve accomplishment of works for security workers. For this, first, activities of security workers are discussed. Second, perception of employees of companies for the necessity of security workers, non-necessity of security workers, qualification requirements of security workers for improving business recognition were established as a framework of the study. Changes for recognition of security works in modern life are a little falling behind compared to unstopping economic development and diversifying job classifications. Even at present, expression of security works is still regarded as manager of facilities or apartments in the past. In other words, it is recognized as a simple change of title and names from apartment guard to security workers. Security works in the modern job classification is settling down as a professional field of facility management and as a part of various controls such as protection and security and its field is also expanding. It is a professional job with the purpose to analyze and prevent diverse criminal actions occurring in the society and also to introduce alternative measures with the role to prevent accidents to be occurred in variety in advance instead of simple working format taking a fixed guard post. Area of security works for the purpose of maximizing necessity of security works shall have equipped with deployment of professional security workers, consideration of business satisfaction of security workers, prevention education for rapidly changing safety accidents, and substantiality in the field. We expect to have more sophisticated area of security works with ceaseless efforts and with instillation of recognition of professionalism by security workers themselves.

• Environmental and Resource Economics Review
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• v.16 no.3
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• pp.549-574
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• 2007

This paper was intended to evaluate environmental policies of South Korea and compare its environmental sustainability with other Eastern Asian countries in terms of some sustainability measures. To meet the purpose, the paper is composed of three parts: a brief and critical review of Korea's current environmental policies, comparison of its sustainability with other Eastern Asian countries in terms of well-known environmental sustainability indices, and comparison in terms of a less well-known alternative measure. Korea's environmental policies as stipulated in "Green Vision 21", "Green Korea 2005" were evaluated in light of OECD EPRK 2006. Korea's environmental performance is then compared with other countries based on such environmental sustainability indices as EF, ESI, EPI and EVI. Unfortunately the well-publicized indices to measure sustainable development (SD) seem to fail in measunng SD and in providing comparability, because it does not base on the genuine concept of SD. Therefore, we tried to suggest an alternative measurement in terms of sustainability quantity (SQ), which is presented for South Korea and her major trading partners, such as USA, Japan and China.

• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.70-75
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• 2000

The recycled single crystal silicon wafers have been fabricated into solar cells. It can be a solution for the high cost in materials for solar cells and recycling of materials. So, p-type (100) single crystal silicon wafers with high resistivity of $10-14\;{\Omega}cm$ and the thickness of $650\;{\mu}m$ were used for the fabrication of solar cells. Optimistic conditions of formation of back surface field, surface texturing and anti-reflection coating were studied for getting high efficiency. In addition, thickness variation of solar cell was also studied for increase of efficiency. As a result, the solar cell with efficiency of 10% with a curve fill factor of 0.53 was fabricated with the wafers which have the area of $4\;cm^2$ and thickness of $300\;{\mu}m$. According to above results, recycling possibility of wasted wafers to single crystal silicon solar cells was confirmed.

• Korean Journal of Plant Resources
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• v.24 no.1
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• pp.69-75
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• 2011

This study was conducted to investigate the variation of cone, seed and germination characteristics among populations and among individuals within populations of Picea jezoensis(Siebold & Zuccarini) Carriere distributed in Korea. Cone collected from 25 trees in two natural populations(Mt. Jiri and Mt. Dokyu) and their thirteen cone and seed characteristics as well as three germination behaviors were analyzed. Statistical analysis showed significant differences among populations and among individuals within populations in 9 traits except for seed breadth, seed weight, index of seed wing and mean germination time. Generally, morphological variation of cone and seed wings from Mt. Jiri population has smaller and longer than those of Mt. Dokyu population. Percentage of sound seeds and Tetrazolium test from Mt. Jiri population showed 1.79 and 1.87 higher values than Mt. Dokyu population, respectively. The maximum germination percentage was obtained at the optimum temperature of $20^{\circ}C$ and in this case, mean germination time and germination rate showed 7.5 days and 2.9 ea./day, respectively. In seed germination behaviors, percentage(40.7%) and rate(0.90 ea./day) of germination in Mt. Jiri population were more higher and faster than those of Mt. Dokyu population(17.7%, 0.37 ea./day). According to correlation analysis, P. jezoensis populations with small restricted distribution may have been reduced because seed qualities were correlated with increased levels of inbreeding and disproportion flowering.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.2
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• pp.71-81
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• 2002

The study was carried out to develop nursery soil for rice seedling of phyllite. First of all, physico-chemical properties of used phyllite in the study through the analysis for agricultural utilization evaluation are as following. Bulk density(BD) of phyllite was $1.31g/cm^3$ each other and porosity had 65% of entire pore size. Also, the water holding capacity(WHC) was 43% at 1/3bar pressure, which phyllite has high WHC. According to, the results the experiments for nursery soil were conducted by mixing the materials such as phyllite, zeolite and hill soil. The mixing ratios were 30, 50, and 70% for zeolite and hill soil into phyllite. These mixed materials were packed in a box by adding 0, 1 and 2g of N-fertilizer. At seedling test, there were increases in the growth of shoot and root of rice for phyllite to zeolite and phyllite to hill soil, respectively. On the other hand, the length of leaf increased with increasing application rate of phyllite, while length and a number of root increased with increasing application rate of hill soil. The growth in the plots of phyllite to zeolite and phyllite to hill soil was better than in control plot. Finally, phyllite plot had efficient results when it compared with others and the study used with phyllite will have to more research and effort for agricultural useful material.