• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.346-346
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• 2007

압전세라믹 재료는 현재 압전 변압기, actuator, transducer, sensor, speaker 등에 광범위하게 이용이 되고 있다. 이 중에서 압전세라믹 소결체를 이용한 스피커의 제조는 가공이 까다롭고, 대형의 크기로 제작 시 소자가 깨지는 등의 많은 제약을 받고 있으며, 저음 특성이 떨어져 응용 범위가 한정되어 있다. 따라서 최근에는 이러한 단점을 극복하기 위하여 세라믹/고분자 복합체를 이용한 필름 스피커를 제작하고자 시도하고 있다. 이러한 세라믹/고분자 0-3형 압전 복합체를 이용할 경우, 제품의 경량화를 실현할 수 있고, 크기나 환경의 영향을 거의 받지 않으므로, 고기능성 스피커로의 응용에 적합할 것으로 보인다. 따라서 본 연구에서는 PZT계의 세라믹와 PVDF, PVDF-TrFE, Polyester, acrylic resin 등의 여러 고분자 물질과의 복합체를 제조하여 압전특성을 평가하였다. 본 실험은 먼저 $(Pb_{1-a-b}Ba_aCd_b)(Zr_xTi_{1-x})_{1-c-d}(Ni_{1/3}Nb_{2/3})_c(Zn_{1/3}Nb_{2/3})_dO_3$ (이하 PZT라 표기)의 최적화 조성을 선택하여, $1050^{\circ}C$에서 소결된 분말을 48시간 ball milling방법 로 약 $1{\mu}m$ 크기로 분쇄하였다. 고분자 물질들은 알맞은 용제들을 선택하여 녹였다. 그 다음 소결된 PZT분말과 고분자를 50:50, 60:40, 65:35, 70:30등의 무게 분율로 혼합하고, 분산제, 소포제 등을 첨가하여 3단 roll mill을 이용하여 충분히 분산시켜 페이스트 (Paste)를 제조하였다. 제조된 페이스트를 ITO가 코팅된 PET필름 위에 스크린 프린팅 법을 사용하여 인쇄하여 $120^{\circ}C$에서 5분간 건조하였다. 코팅된 복합체의 두께는 약 $80{\mu}m$ 정도로 측정되었다. Ag 페이스트를 이용한 상부 전극 형성에도 스크린 프린팅 법을 적용하였다. 이를 $120^{\circ}C$에서 4 kV/mm의 DC 전계로 분극 공정을 수행한 후 전기적 특성을 평가하였다. 유전특성을 조사하기 위해서 LCR meter (EDC-1620)를 사용하였고, 시편의 결정구조는 XRD (Rigaku; D/MAX-2500H)을 통해 분석하였으며, 전자현미경(SEM)을 이용하여 미세구조를 분석하였다. 압전 전하상수$(d_{33})$ 값은 APC 8000 모델을 이용하여 측정하였다. PZT의 혼합비가 증가할수록 비유전율 및 압전 전하 상수 등의 전기적 특성이 증가되었다. 또 여러 고분자 물질 중에서 PVDF-TrFE 수지가 가장 우수한 특성을 보였다. 이는 PVDF-TrFE 수지가 압전성을 나타내기 때문인 것으로 판단되었다.

• Korean Journal of Ichthyology
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• v.9 no.2
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• pp.178-185
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• 1997

From November 1996 to April 1997, the rockfish, Sebastiscus marmoratus (Cuvier et Valenciennes) was reared in laboratory, and observed eggs development and morphology of larvae. The eggs of this species are demersal and adhesive, and their diameter were varied within 0.76 to 0.82 mm. The color of yolk is light yellow in early developmental stage, and then turned to orange before hatching out. The yolk contained numerous tiny oil globules. Hatching began about 33 hours and 30 minutes after insemination at $10.0{\sim}14.5^{\circ}C$ of waters. The newly hatched larvae were elongated in shape and 1.62~1.68 mm in total length (TL) with 7~8+16=23~24 myomeres. The larvae absorbed yolk material and oil globule completely in 14 days after hatching and became postlarvae. The spawning season of adult rockfish may be supposed to be from February to March in the southern sea of Korea.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.370-377
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• 2007

The spawning host selection and adaptive characteristics in life history were investigated for Sarcocheilichthys nigripinnis morii which has similar habit of spawning with acheilognathine fishes. The fertilized eggs of the species were found in the mantle cavity of Corbicula papyracea and C. fluminea among the bivalves collected from same locality, meaning the species specific host selection for the spawning. We considered that the differences in the status of expanding egg membrane after hydration, fewer number of eggs settled into the mantle cavity and having eleutheroembryo with developed organ would be some evidences of specific reproductive strategy for this species. But the status of developed surface blood circulation was thought to be a compensation for the parasitism. The pigmentation of melanopore delayed to late embryo and the spot on the caudal region was a characteristics of this species appeared in the early life history.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.157-165
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• 1987

On January 16, 1986, mature adults of smooth lumpsucker, Aptocyclus ventricosus (Pallas) were collected from the coastal water of Okkye, Myongju-gun, Kangwon-do, Korea. The authors carried out artificial insemination on the boat. The eggs were incubated and the larvae were reared in laboratory. During the incubation period water temperature fluctuated between $7.5^{\circ}C$ and $21.4^{\circ}C$. The eggs of smooth lumpsucker are demersal and adhesive. The eggs diameters were varied from 2.28 to 2.36 mm. The hatching took place in ca. 725 hours after fertilization. The newly hatched larvae were 6.0-6.9 mm in total length. The features of the hatched larvae lie in the tadpole-like body form and in the well developed sucking disk, namely the ventral fins. 17 days after hatching, the larva attained 9.1 mm in total length. The gill opening retained a small opening at its upper part. Melanophores were developed on the tail. 31 days after hatching, the larva attained 10.6 mm in total length, and became juvenile. The first dorsal fin was disappeared. 105 days after hatching, the larvae attained 15.4-17.5 mm in total length.

• Journal of Life Science
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• v.20 no.8
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• pp.1249-1253
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• 2010

Sericin is a type of high molecular weight water-soluble glycoprotein surrounding fibroin (silk protein) that has been used as a cell culture supplement and accelerates cell proliferation in various serum-free media. The purpose of this study was to investigate the enhancing effect of thyroglobulin (Tg) secretion by sericin in thyrocytes, FRTL-5 cells. While Tg-mRNA expression was not enhanced, a secreted form of Tg was obviously increased by sericin. In this status, expression of both endoplasmic reticulum (ER) molecular chaperones (Bip & calreticulin) and ER membrane proteins (IRE1, PERK & ATF6) was enhanced. The proximal step of IRE1, XBP1 mRNA splicing was slightly detected however, the proximal step of PERK, phosphorylation of $eIF2{\alpha}$, was changeless. In addition, sericin enhanced cell viability by the MTT assay. The above results showing the ability of sericin to promote protein production demonstrated its potential usefulness as a new biomaterial.

• Korean Journal of Ichthyology
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• v.13 no.1
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• pp.69-73
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• 2001

Observation of morphological changes during larval and juvenile stages of the halfbeak fish, Hyporhampus sajori (Temminck et Schlegel), was made based on samples of fertilized eggs collected on the shores of Youngil Bay, Phohang-shi, Korea, on May 27, 1991, and incubated in the laboratory. During the incubation period, water temperature fluctuated between $17.6^{\circ}C$ and $23.2^{\circ}C$. The newly hatched larvae were elongated and 7.0~8.50 mm in total length (TL) with 40~42+17~18 = 59~60 myotomes. Numerous melanophores were on the head, mid-dorsal part of the body, intestine, and the tail part of the notochord. Three days after hatching the larvae had attained 8.60~10.90 m in TL, had completely absorbed the yolk, and the caudal notochord was flexed $45^{\circ}$ upward. At this time, it was attained postlarvae stage. Thirty-seven days after hatching the postlarvae were 32.37~44.95 mm in TL and had reached the juvenile stage. All fins were formed with a complete set of fin rays with the following counts: dorsal fin rays 16~17; pectoral f in rays 6; ventral fin rays 12~14; caudal fin rays 11~12+11~12 = 22~24.

• Korean Journal of Medicinal Crop Science
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• v.5 no.1
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• pp.14-20
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• 1997

To increase the efficiency of the callus induction in anther culture of Schizandra chinensis, the effects of culture stage, low temperature pretreatment, growth regulators, sucrose and gelling agents were tested on Murashige and Skoog's medium. And the effects of ABA and $AgNO_3$ on organogenesis were investigated. The most suitable stage for anther culture was at the middle to late uninucleate stage, of which the flower size was $6.2{\pm}0.6{\times}4.0{\pm}0.4mm(Length{\times}width)$, and the frequency of callus induction was 13.3%. The effect of low-temperature pretreatment on callus induction was highest as 12.5% in the trearment for 8 days at $4^{\circ}C$. The combination of 1.0 mg/L 2, 4-D and 0.25 mg/L kinetin for callus induction was most effective as 8.3% among various media. The frequency of callus induction was excellent as 10.8% in 4% sucrose. Effect of gelling agents on callus induction was highest as 9.0% on 0.6% Gelrite medium. The prevention of callus browning was effective on the media supplemented with ABA and $AgNO_3$ and rooting was promoted on medium supplemented with 5 mg/L ABA. But shoot was not developed.

• Korean Journal of Plant Taxonomy
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• v.40 no.4
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• pp.226-233
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• 2010

An intensive study of the embryology of Gymnospermium microrrhynchum was conducted to provide information regarding a discussion of the phylogenetic relationships of the genus, which is yet unstudied. Our results indicated that Gymnospermium is similar to other genera of Berberidaceae in terms of its embryological features. Nevertheless, newly reported and unique features are the well-developed endothelium and the undifferentiated seed coat type. Until the study of Gymnospermium, it may have been considered to be closer to Caulophyllum and Leontice in the tribe Leonticeae. These three genera share many morphological features as well as molecular similarities, by which they are kept in the same tribe, Leonticeae. However, very little detailed embryological data regarding these genera have been published thus far. Gymnospermium was characterized according to the basic type of anther wall formation as well as its glandular tapetum, successive cytokinesis in the microspore mother cell, two-celled mature pollen grains, anatropous and crassinucellate ovules with a nucellar cap, well-developed endothelium, its Polygonum type of embryo sac formation, its nuclear type of endosperm formation, and its undifferentiated seed coat type. In comparison with Nandina, there are many differences, such as the dehiscence of the anther, the cytokinesis in the microspore mother cells, the shape of the megaspore dyad, and the seed characteristics. Although we had no available detailed embryological information regarding Caulophyllum and Leontice, which are genera that are more closely related to Gymnospermium, we could deduce from the phylogenetic relationship that Gymnospermium, Caulophyllum, and Leontice are more closely related to each other than other genera of Berberidaceae on the basis of the seed characteristics.

• Korean Journal of Agricultural Science
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• v.39 no.4
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• pp.497-502
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• 2012

Since the year 2000, the production and consumption of broccoli have rapidly increased in Korea. And, the average production area and amount were about 1,700 ha and 29,000 ton for the past 5 years. Even with the increase of these cultivation and consumption, more than 95% of the broccoli seeds are currently imported from foreign countries such as Japan and Netherlands. Therefore, development of domestic broccoli varieties is needed to relieve Korean farmers' production cost for broccoli. In this situation, National Institute of Horticultural and Herbal Science (NIHHS) of Korea has tried to develop F1 hybrid varieties from elite lines that were obtained by microspore cultivation method from 2008. As the results, about 850 lines of broccoli were obtained and self-pollinated. Then their ploidy levels of the genome were confirmed to select double haploid (D.H.) lines. And the D.H. lines' horticultural traits were evaluated in open field. After the selection of 17 elite D.H. lines, they were cross-pollinated with a male sterile (MS) line to produce F1 hybrid seeds. After 2 to 3 years field trials of these F1 hybrid varieties at the area of Suwon, Gangneung, and Jeju respectively, two hybrid varieties such as 'Wongyo8011' and 'Wongyo8012' are selected for the application of variety protection. With these 4 years of research, we found that the microspore cultivation method is a powerful tool for the conventional breeding program, especially for the development of various inbred lines and even F1 hybrid varieties in short time.

• Journal of Korean Society of Forest Science
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• v.75 no.1
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• pp.25-31
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• 1986

In order to contribute to the Korean tea-plant culture and tea industry by means of increasing the production of tea-plants, I have performed the tissue culture of the organs of the anther, leaf and stem. As for the culture-material, I have used the anther of tea (Thea sinensis) at the tetrad uninucleate microspore stage and used medium of modified Murashige and Skoog as the basal medium supplemented with the growth regulators of NAA and 2, 4-D, yeast, kinetin and others at various concentrations. As for the handling of material, I have followed the common methods of sterilization and microtoming and paraffine imbedding method and observed systematically periodic changes of the microspores in culture. I have divided the leaf, stem and root into segments and sterilized them and used the modified Murashige and Skoog as the basal medium and observed the differentiation of roots and callus and the results are as follows. 1. In case of anther, I have found 2n callus was found in 30 out of 100 segments in M2 medium. 2. The differentiation of roots appeared in 24.5% of total leaf segments cultured and in 50.5% of stem and in 43.9% of root. 3. When the differentiation of stem in different parts was observed, the most frequent differentiation was found in the second part of all the 4 parts. 4. The most frequent formation of callus was noticed from the anther-walls in case of anther culture and from the veins in case of leaf culture. It is concluded that the seedlings of tea-plant could be multiplied most by means of tissue culture of the second part of the tea-plant stem and reduction in the expenditures of tea-plant propagation was possible through tissue culture.