• Development and Reproduction
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• v.6 no.1
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• pp.45-54
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• 2002

Reproductive activity of golden hamsters(Mesocricetus auratus) is regulated by the photoperiod. They are sexually active in summer and inactive in winter. Melatonin, a pineal hormone, has been known to mediate sexual activities in seasonal breeding animals. Melatonin receptor was recently identified in several animal species including hmm. But little has been known about it in relation to the reproductive activities of golden hamsters. By using reverse transcription polymerase chain reaction(RT-PCR) methods, a portion of the melatonin receptor gene(309 nucleotides) was identified in golden hamsters. The nucleotide sequence of the melatonin receptor and the amino acid sequence deduced were compared to those reported in other animals. Melatonin receptors were obviously detected in hypothalamus, pituitary containing pars tuberalis, blood, and spleen. Although the testicular weights and the levels of reproductive hormones were dramatically affected by photoperiods, the expression of melatonin receptor was not markedly changed by them. These results suggest that the action of melatonin in regulating reproduction might be mainly due to the affinity of melatonin receptor rather than the density fi melatonin receptor.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.1
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• pp.1-10
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• 2024

As increasing demands for a floating structure expanded from offshore industry facilities to living facilities, it has emerged that necessity of techniques to reduce motions of a floating structure. This study present a floating structure with porosity on the outer surface of the floater. Under each regular and irregular wave, responses of the floater was investigated in frequency domain. The proposed structure is composed of inner and outer floaters, which are connected to each other and the outer wall is perforated, and the heave and the pitch of floaters with different perforation rates (0~30%) were compared with at both the center and the edge. The results showed that pitch responses can be decreased by increasing of perforation rate of the floater. Comparing with responses of the non-perforated floater, those of the proposed floating structure were reduced to above 10% and 2%, respectively for regular and irregular wave conditions.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.80-86
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• 2009

In this study, binderless zeolite BaX granule, an effective adsorbent for the separation of p-xylene was made. This adsorbent which has a sufficient strength, high specific surface area and selectivity to p-xylene was prepared by various steps, such as granulation process, calcination, binderless treatment, ion-exchange, and activation. In the granulation, the concentration of colloidal silica solution was controlled in order to confirm the effect of $SiO_2$ contents after binderless treatment. As a result, we confirmed that the compressive strength of granule after binderless treatment was increasing with increasing proportion of $SiO_2$ in the granule. And then Na-ion in granule was exchanged with Ba-ion by successive batch ion-exchange process. And then prepared adsorbents were tested for p-xylene separation by batch adsorption at $90^{\circ}C$. As a results of batch adsortion test, we confirmed that prepared adsorbents have a high selectivity to p-xylene. Also, it could be conformed that the prepared binderless zeolite BaX has a sufficient compressive strength (0.450 kgf), high specific surface area $(647.57m^2/g)$, high crystallinity (98.5% compared with zeolite NaX powder), and selectivity to p-xylene.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.115-123
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• 2007

Immobilization of contaminants in subsurface environment is one of the major processes that determine their fate. Especially, immobilization by oxidative-coupling reactions, which is irreversible in the bio-chemical reactions and results in a significant reduction of toxicity, can be successfully applied for the remediation of contaminated soil and groundwater more effectively than conventional degradation. As a catalyst of this oxidative-coupling reaction, manganese oxide has many advantages in practical aspects as compared to microorganisms or oxidoreductive enzymes extracted from microorganisms, fungi, or plants. This paper is to present recent research achievements on the treatment mechanisms of various organic contaminants by manganese oxide. Especially, treatment methods of non-reactive organic compounds to Mn oxide are the main focus; i.e., application of reaction mediator, PAHs treatment method, combination with an appropriate pretreatment such as reduction using $Fe^0$, which suggests the potential of a wide range of engineering application. Concerning the natural carbon cycle processes, immobilization and stabilization by oxidative coupling reaction can be effectively applied as a environmentally-friend remediation method especially for aromatic contaminants which possess a high resistance to degradation.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.208.1-208.1
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• 2016

히드라란 단세포 생물로써 강장동물에 속한다. 촉수가 많이 있으며, 그 촉수에는 독이 있다. 번식 방식으로는 출아법을 이용한다. 출아를 할 때에는 한 마리가 아닌 여러 마리의 히드라가 동시에 출아를 하기도 하며, 출아를 하고 있는 히드라는 촉수가 들어난 순간부터 먹이 섭취가 가능해진다. 이 출아법을 이용하여 번식을 하는 히드라가 DBD처리를 했을 시, 히드라 출아에 차이를 보인다면 다른 생물에게도 DBD 처리를 했을 시, 영향을 미친다고 생각하고 실험을 진행하였다. DBD(Dielectric Barrier Discharge)는 두 전극 사이에 유전체층이 있으며, 외부에서 교류 전압을 가해준다. 그러면 유전체 사이에서 방전이 발생되는데, 방전된 것을 플라즈마라고 한다. DBD라는 유전체 장벽 방전으로써 주위를 이온화 시켜 만드는 플라즈마에 유전체를 씌어 생물에게 최대한 해가 되지 않도록 만든 것이다. 유전체 장벽 방전에ROS(Reactive Oxygen Species)라는 산소와 결합된 기체들이 생성된다. DBD로 인해서 생성되는 ROS를 히드라에 처리했을 경우 히드라 출아수에 변화를 통해서 해를 끼치는 정도를 알아보고자 하였다. 그 결과 아르곤 기체에 의한 ROS로 처리한 히드라는 대조군 보다 히드라의 출아수의 변화가 있는 것으로 관찰되었고, 공기를 이용하여 방전한 DBD의 ROS로 처리한 히드라는 대조 군과 비교하여 큰 변화가 없어 보였다. 따라서 아르곤 대기압 DBD플라즈마를 이용하여 만든 ROS가 히드라에게 직접적인 영향을 준 것으로 보였다. 이 결과를 토대로 아르곤DBD를 이용한 ROS 처리는 생물에게 영향을 줄 수 있다는 것을 이 실험을 통해 간접적으로 확인해 볼 수 있었다.

• Korean Journal of Environmental Agriculture
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• v.14 no.2
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• pp.179-185
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• 1995

Three aminothio derivatives of carbofuran including carbosulfan, furathiocarb and benfuracarb were subjected to the degradation study in soils to investigate how fast and efficiently carbofuran would be evolved from them. Carbofuran was rapidly released from the derivatives in soils as the carbamoyl nitrogen-sulfur bond cleaved. Their degradation rates in soils, with half-lives of $23{\sim}68$ hours, were largely affected by structures of aminothio moieties and soil moisture conditions. Conversion rates into carbofuran ranged from 64 to 84% in soils on the basis of parent compounds 5 days after treatment. Application of aminothio derivatives led to less drastic increase in the carbofuran level in soils than when carbofuran was applied as such, and hence this might result in lower side effects in situ.

• Journal of the Korean Vacuum Society
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• v.3 no.2
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• pp.190-197
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• 1994

본 연구에서는 DC magnetron 스퍼터링법을 이용하여 고정밀, 고저항 저항체 박막으로 TaNx film을 제조하였을 때 형성될 수 있는 화합물 중 TaN0.1, TaN0.8과 TaN 박막의 Rs와 TCR특성을 평가하 고 film층의 우선방향성을 XRD를 이용하여 판명한 뒤 저항체의 Rs와 TCR에 미치는 영향을 조사하였 다. TaN0.1 박막이 35$\Omega$/$\square$의 면저항값과 안정된 TCR값을 나타내는 것을 알수 있었다. 두께50~200nm 의 TaN0.1과 Alumina 기판 사이에 정(+)의 TCR을 갖는 약 50nm의 Cr층을 증착하였을 때 Rs는 180$\Omega$/ $\square$ 과 TCR는 20ppm/$^{\circ}C$인 적층박막을 제조할 수 있었다. TaN0.1, TaN0.8 과 TaN 시편에서 화합물 형성 에 따른 Ta의 결합에너지를 ESCA를 이용하여 조사하였다. 이상의 연구결과로부터 TaN0.1 film이 TaNfilm 보다 고정밀, 고저항 박막 저항체 제조에 있어 우수한 전기저항 특성을 가지며 Cr 중간층 형성 으로 TCR이 $\pm$ppm/$^{\circ}C$정도로 안정된 고정밀 다층 저항체 박막을 형성할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.442-442
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• 2013

ZnO의 나노 구조는 화학적으로 안정하고 큰 결합에너지를 가지는 성질 때문에 청색 영역에서 작동하는 광전소자의 제작에 대단히 유용하다. 전기 화학 증착법으로 성장된 ZnO의 나노구조는 가격이 저렴하고 낮은 온도에서 성장이 가능하며 대면적화를 할 수 있는 장점이 있다. 전기 화학 증착법으로 ZnO을 성장할 때 ITO 기판을 음극으로 백금 전극을 양극으로 사용하였고 기준 전극은 Ag/AgCl을 사용하였다. Potassium chloride의 몰 농도를 변화하면서 ZnO 나노구조를 성장하였다. 성장한 ZnO 나노구조를 $400^{\circ}C$에서 2분 정도 열처리를 하였다. 성장된 ZnO을 X-선 회절 결과는 (0002) 피크가 $34.35^{\circ}$에서 나타났다. 주사 전자 현미경상은 Potassium chloride의 몰 농도가 낮을 때 성장한 ZnO 나노구조체가 고르게 성장되는 것을 알 수 있었다. Potassium chloride의 농도가 변화하면 ZnO 나노구조체의 형태가 변화하는 것을 알 수 있었다. 300 K에서 광루미네선스 스펙트럼은 형성된 나노구조가 엑시톤과 관련된 피크가 potassium chloride 농도에 따라 변화하게 되는 것을 알 수 있었다. 이 실험결과는 ZnO 나노구조의미세구조와 광학적 성질이 potassium chloride의 농도에 영향을 많이 받는 것을 알 수 있었다.

• Journal of the Korean Chemical Society
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• v.39 no.5
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• pp.371-378
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• 1995

The triazacrown compound, 1,7-dioxa-4,10,13-triazacyclopentadecane trihydrobromide salt (Na3O2-3HBr) was synthesized. And this compound was used to synthesize the new ion exchanger, which combined with Merrifield peptide resin. This new ion exchanger had a capacity of 3.2 meq/g dry resin. And the distribution coefficients of alkali and alkaline earth metal ions on this ion exchanger in the various concentrations of hydrochloric acid were determined. The ion exchange behaviors of alkali and alkaline earth metal ions in the various hydrochloric acid concentrations are, also, discussed.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.29-34
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• 2003

Full-scale test facility is a huge system which is integrated by many subsystems. There are several critical elements in test facility system. Those elements may cause undesirably test article failure during testing. Therefore, test facility monitoring system which indicates the operating status of the critical elements is required for performing full-scale structural test. Selection of critical element and design of this monitoring system are explained in detail in this paper. The monitoring system developed are being applied to T-50 full-scale static test, will be expended for full-scale fatigue test in the near future.