• Annual Conference of KIPS
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• 2004.11a
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• pp.871-874
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• 2004

멀티미디어 컨텐츠의 저작권 보호를 위한 워터마크 기법은 현재 많은 연구가 진행 중에 있다. 본 논문은 MPEG 비디오의 압축 과정에서 마지막 단계인 VLC 영역에 DCT된 워터마크의 키 값을 적용하여 얻어낸 신호를 run-level 쌍의 level 값의 부호에 따라 선택적으로 삽입하는 방범을 제안하였다. 양자화 된 DCT계수들의 고주파수 영역은 level 값을 거의 가지지 않기 때문에 고주파수영역의 계수 값이 제거되어도 워터마크의 정보는 대부분 살아남아 공격에 강인함을 보이며 압축의 마지막단계에 정보를 삽입하여 실시간 적용이 가능하다는 장점을 보여 주었다.

• Annual Conference of KIPS
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• 2003.05a
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• pp.655-658
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• 2003

멀티미디어 기술과 인터넷의 급속한 발전으로 인해 영상 데이터의 복사가 더욱 쉬워지고 있다. 이러한 작품들을 보호하기 위해 데이터 안에 저작권을 표시할 수 있는 기술들이 필요해지고 지난 몇 년간 데이터에 다른 정보를 삽입할 수 있는 많은 기법들이 제안되어 왔다. 본 논문에서는 RGB 칼라 영상을 인간 시각 특성을 나타내는 I.UV 좌표계로 변화하여 인간 시각에 둔감한 U영역에 키를 이용하여 랜덤하게 워터마크를 삽입하고 추출하는 워터마킹 기법을 제안한다. 또한 웨이브릿(Wavelet) 변환을 사용하였으며 비교적 공격에 강한 고주파수 영역에 삽입하였고 추출시는 삽입한 키 값을 이용하여 워터마크를 추출한다. 제안한 워터마킹 기법은 시각적으로 보이지 않고, 가우시안 노이즈(Gaussian Noise) 및 필터링(filtering)에도 견고함을 보인다.

• Journal of the Optical Society of Korea
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• v.7 no.2
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• pp.119-125
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• 2003

We demonstrate parametric resonance in a magneto-optical trap. When we modulate the intensity of the cooling laser at about twice the resonant frequency of the trap, the atoms in the trap are divided into two parts and oscillate with 180 degree phase difference with the finite length due to nonlinearity of the trap potential. These are the effects of general nonlinear dynamics, called the Hopf bifurcation, or limit cycle motion. The amplitude and the phase of the oscillations are measured and compared with the theoretical calculations based on simple Doppler cooling theory. The experimental results are in excellent agreement with the simulation results based on the simple Doppler cooling theory.

• Journal of the Korean Wood Science and Technology
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• v.32 no.6
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• pp.43-49
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• 2004

Three flavonoids, quercetin, taxifolin, and kaempferol were isolated from the woods of Liriodendron tulipifera. Their structures were determined by spectral analysis. Based on 1, l-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity method, the antioxidative activities of three isolated compounds and their acetates were measured in order to search for natural antioxidants. The IC₅₀ of quercetin (1), taxifolin (2), and kaempferol (3) were 3.6, 3.9, and 4.1 ㎍/㎖, respectively.

• Archives of Craniofacial Surgery
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• v.23 no.6
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• pp.278-281
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• 2022

The face is one of the most important parts of the body. Untreated facial fractures can result in deformities that can be harmful to patients. Three-dimensional (3D) printing is a rapidly evolving technology that has recently been widely applied in the medical field as it can potentially improve patient treatment. Although 3D printing technology is mostly used for craniofacial surgery, some studies have proved that it can be used to treat nasoethmoid orbital fractures. In this study, a patient-customized plate was constructed using a 3D printer and applied in a simulated surgery for the treatment of nasoethmoid orbital fracture.

• Journal of Korean Neurosurgical Society
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• v.30 no.10
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• pp.1233-1236
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• 2001

The intradural lumbar disc herniation which was first described by Dandy in 1942 is unusual. The pathogenesis is obscure and preoperative diagnosis is not easy. The patient usually have more severe neurologic deficits than those found in the much more common extradural disc herniations. We experienced two cases of the intradural lumbar disc herniation who had previous disc operations and the symptoms and neurologic signs were improved after removal of the intradural sequestration of disc fragments.

• Development and Reproduction
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• v.15 no.1
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• pp.53-59
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• 2011

Sex steroid hormones are key molecules to prepare the decidual response and their levels are important in this process. Imbalances of the levels of steroid hormones are cause of implantation failure and other diseases including physical weakness. Androgen replacement therapy or selective androgen receptor modulator are used to overcome various diseases but long-term use may cause of side effects. In previous report, it is suggested that the steroid hormonal complexes derived from pig enhance the proliferation of satellite cell. Therefore, to evaluate the possible usage of steroid hormonal complex derived from pig testis (tS-C), the effects of tS-C on uterine response were studied using the model of artificial decidua. tS-C did not disturb the rhythmical estrus cycle. Artificial-induced decidual response was normally induced in tS-C administered mice. The histological characters of the decidua of tS-C administered mice were not different from the vehicle. The expression patterns of molecular markers of decidua were not different between vehicle and tS-C group. Collectively these results suggested that tS-C does not disturb the uterine responsibility to the embryo. In addition, our results suggested that tS-C can be applied to overcome the various problems such as loss of muscle mass and anemia.

• Journal of Applied Biological Chemistry
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• v.50 no.4
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• pp.275-280
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• 2007

Dried unripe fruits of Rubus coreanus Miq. were extracted with 80% aqueous MeOH and the concentrated extract was partitioned with EtOAc and $H_2O$. From the EtOAc fraction, four triterpenoids were isolated through repeated silica gel, ODS and Sephadex LH-20 column chromatographies. From the result of physico-chemical data including NMR, MS aud IR, the chemical structures of the compounds were determined as tormentic acid (1), myrianthic acid (2), hovenic acid (3) and 2${\alpha}$,3${\beta}$,19${\beta}$,23-tetrahydroxylolean-12-en-28-oic acid (4). Compounds 3 and 4 were isolated for the first time from this plant. All isolated compounds were evaluated for cytotoxic activity against human colon carcinoma cells using in vitro three-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, compound 3 showed a higher cytotoxicity ($IC_{50}$ = 7.8 ${\mu}M$) than doxorubicin ($IC_{50}$= 50 ${\mu}M$).

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.1
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• pp.148-154
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• 2008

The butanol extract of Euonymus alatus (BEA) induced dose-dependent relaxation of phenylephrine-precontracted aorta, which was abolished by removal of functional endothelium. Pre-treatment of the endothelium-intact aortic tissues with $N^G-nitro-L-arginine methylester$ (L-NAME), and 1 H-[1,2,4]-oxadiazole- [$4,3-{\alpha}$]-quinoxalin-1-one (ODQ) inhibited the relaxation induced by BEA, respectively. BEA-induced vascular relaxation was not blocked by glibenclamide, tetraethylammonium (TEA), indomethacin, atropine, propranolol, verapamil, and diltiazem, respectively. Moreover, BEA inhibits phenylephrine-induced vascular constriction in a dose-dependent manner. These results suggest that BEA relaxes vascular smooth muscle via endothelium-dependent nitric oxide/cGMP signaling.

• Herbal Formula Science
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• v.27 no.2
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• pp.167-178
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• 2019

Objectives : This report describes 45 studies related to the use of Rhizoma dioscoreae main blended prescription from Donguibogam. Methods : The following conclusion were reached through investigations on the prescriptions that use Rhizoma dioscoreae as a key ingredient. Prescriptions that Rhizoma dioscoreae was taken as a monarch drug are utilized for 18 therapeutic purposes, for example, internal injury, stool disease, pediatric disease. In paticular, 24% of prescriptions appear in the chapter of internal injury, and 18% of those appear in the chapter of stool. Results : Prescriptions that utilize Rhizoma dioscoreae as the main ingredient are used in the treatment of indigestion, diarrhea and paralysis. Rhizoma dioscoreae is used in pathogenic factors such as water, water with damp, and used in pathology related to stomach system. Conclusions : The dosage of Rhizoma dioscoreae is 8li(about 0.29 gram) to 3jeon(about 11.25 gram), however 1jeon(about 3.75 gram) has been taken the most for clinical application. Sagunjatang and Siljangsan is the most useful base prescription which use the Rhizoma dioscoreae as the main ingredient.