• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1385-1397
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• 2024

Bentonite is a recommended material for the multiple barriers in the final disposal of low-level radioactive waste (LLW) to prevent groundwater intrusion and nuclear species migration. However, after drying-wetting cycling during the repository construction stage and ion exchange with the concrete barrier in the long-term repository, the bentonite mechanical behaviors, including swelling capacity and hydraulic conductivity, would be further influenced by the groundwater intrusion, resulting in radioactive leakage. To comprehensively examine the factors on the mechanical characteristics of bentonite, this study presented scenarios involving MX-80 and KV-1 bentonites subjected to drying-wetting cycling and accelerated ion migration. The experiments subsequently measured free swelling, swelling pressure, and hydraulic conductivity of bentonites with intrusions of seawater, high pH, and low pH solutions. The results indicated that the solutions caused a reduction in swelling volume and pressure, and an increase in hydraulic conductivity. Specifically, the swelling capability of bentonite with drying-wetting cycling in the seawater decreased significantly by 60%, while hydraulic conductivity increased by more than three times. Therefore, the study suggested minimizing drying-wetting cycling and preventing seawater intrusion, ensuring a long service life of the multiple barriers in the LLW repository.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.233-237
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• 2005

수화의 인식 및 표현 기술에 대한 관련 연구는 수화 인식을 통한 건청인과의 의사 전달, 가상현실에서의 손동작 인식 등을 대상으로 여러 방면으로의 접근 및 연구 결과를 도출하고 있다. 그러나 이들 연구의 대부분 데스크탑 PC기반의 수신호(Hand signal) 제어 및 수화 - 손 동작 인식에 목적을 두었고 수화 신호의 획득을 위하여 영상장비를 이용하였으며 이를 바탕으로 단어 위주의 수화 인식 및 표현에 중점을 둔 수화 인식 시스템의 구현을 통해 비장애인과의 자유로운 의사소통을 추구하고 있다. 따라서 본 논문에서는 햅틱 장치로부터 사용자의 의미있는 수화 제스처를 획득하기 위한 접근 방식을 차세대 착용형 PC 플랫폼 기반의 유비쿼터스 환경으로 확대, 적용시켜 제스처 데이터 입력 모듈로부터 새로운 정보의 획득에 있어 한계성을 극복하고 사용자의 편의를 도모할 수 있는 효율적인 데이터 획득 방안을 제시한다. 또한 퍼지 알고리즘 및 RDBMS 모듈을 이용하여 언제, 어디에서나 사용자의 의미 있는 문장형 수화 제스처를 실시간으로 인식하고 표현하는 수화 제스처 인식기를 구현하였다. 본 논문에서는 수화 제스처 입력 모듈(5th Data Glove System과 $Fastrak{\circledR}$)과 차세대 착용형 PC 플랫폼(embedded I.MX21 board)간의 이격거리를 반경 10M의 타원 형태로 구성하고 규정된 위치로 수화 제스처 데이터 입력모듈을 이동시키면서 5인의 피실험자에 대하여 연속적으로 20회의 반복 실험을 수행하였으며 사용자의 동적 제스처 인식 실험결과 92.2% 평균 인식률을 도출하였다.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1692-1696
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• 2011

The reactions of 1H-1,2,4-triazole (Htr) with $MX_2$ ($ZnCl_2$ for 1; $CdBr_2$ for 2) resulted in two coordination polymers, [Zn(tr)Cl]$_n$ (1) and $[Cd(Htr)_2Br_2]_n$ (2). The structural analyses indicate that 1 and 2 feature a 2D layer and 1D triple chain, respectively. In 1, neighouring Zn atoms are connected by ${\mu}_3-1$ ${\kappa}N$: 2 ${\kappa}N$: $4{\kappa}N-tr^-$ anionic ligand into 6- and 16-membered rings, further grow into a 2D sheet. Cd atoms in 2 are bonded by two ${\mu}_2-Br^-$ bridges and neutral ${\mu}_2$-1 ${\kappa}N$: 2 ${\kappa}N$-Htr to form a 1D triple chain. The fluorescent characterizations of 1, 2 and the free Htr ligand feature simlilar emission peakes at 444, 446 and 423 nm respectively, which can be assigned to intra-ligand ${\pi}-{\pi}^*$ transition of (H)tr. The energy gaps of 5.90 eV for 1, 5.16 eV for 2, and 5.93 eV for Htr suggest that the compounds behave as insulators.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.121-129
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• 1984

The adsorption characteristics of heavy metal ions $(Ni^{2+}$, $Zn^{2+}$) on domestic activated carbon which manufactured from the wood, waste rubber and coal has been studied. The following conclusions were obtained by investigating the effect of pH, halides, cyanide and temperature on the absorption of heavy metal ions and by determining absorption rate and absorption isotherms. When heavy metal ions were adsorbed on activated carbon in the pH range from 6 to 7, treated heavy metal ions were almost come to the equilibrium and recovered in the form of complex anions such as $MX_4^{2- }$and $M(CN)_4^{2-}$ in an hour. The absorption isotherms of heavy matel ions were well fitted in Freundlich's equation. Heavy metal complex anions on activated carbon were easily eluted by using 0.1N HCl solution. These results suggest that the complex anions have unexpectedly strong affinity for the surface of activated carbon.

• Korean Journal of Head & Neck Oncology
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• v.18 no.2
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• pp.216-218
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• 2002

A 38-year-old man, who was diagnosed nasopharyngeal carcinoma (stage T4N2Mx) had rapidly growing lower neck mass (at level IV area) with local inflammation sign during concurrent chemoradiotherapy. After we performed Color Doppler sonography and fine needle aspiration biopsy of the neck mass, we differentiated neck soft tissue infection from tumor extension. Size of the mass decreased after antibiotics therapy. It was difficult to differentiate neck infection from tumor progression during treatment in naspharyngeal carcinoma.

• Journal of The Korean Astronomical Society
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• v.36 no.spc1
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• pp.37-44
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• 2003

In this paper, we review recent studies on the magnetic helicity changes of solar active regions by photospheric horizontal motions. Recently, Chae(200l) developed a methodology to determine the magnetic helicity change rate via photospheric horizontal motions. We have applied this methodology to four cases: (1) NOAA AR 8100 which has a series of homologous X-ray flares, (2) three active regions which have four eruptive major X-ray flares, (3) NOAA AR 9236 which has three eruptive X-class flares, and (4) NOAA AR 8668 in which a large filament was under formation. As a result, we have found several interesting results. First, the rate of magnetic helicity injection strongly depends on an active region and its evolution. Its mean rate ranges from 4 to $17 {\times} 10^{40}\;Mx^2\;h^{-1}$. Especially when the homologous flares occurred and when the filament was formed, significant rates of magnetic helicity were continuously deposited in the corona via photospheric shear flows. Second, there is a strong positive correlation between the magnetic helicity accumulated during the flaring time interval of the homologous flares in AR 8100 and the GOES X-ray flux integrated over the flaring time. This indicates that the occurrence of a series of homologous flares is physically related to the accumulation of magnetic helicity in the corona by photospheric shearing motions. Third, impulsive helicity variations took place near the flaring times of some strong flares. These impulsive variations whose time scales are less than one hour are attributed to localized velocity kernels around the polarity inversion line. Fourth, considering the filament eruption associated with an X1.8 flare started about 10 minutes before the impulsive variation of the helicity change rate, we suggest that the impulsive helicity variation is not a cause of the eruptive solar flare but its result. Finally, we discuss the physical implications on these results and our future plans.

• The korean journal of orthodontics
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• v.47 no.1
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• pp.11-20
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• 2017

Objective: This randomized controlled trial aimed to compare the stability of mandibular arch orthodontic treatment outcomes between passive self-ligating and conventional systems during 6 months of retention. Methods: Forty-seven orthodontic patients with mild to moderate crowding malocclusions not requiring extraction were recruited based on inclusion criteria. Patients (mean age $21.58{\pm}2.94years$) were randomized into two groups to receive either passive self-ligating ($Damon^{(R)}$ 3MX, n = 23) or conventional system (Gemini MBT, n = 24) orthodontic treatment. Direct measurements of the final sample comprising 20 study models per group were performed using a digital caliper at the debonding stage, and 1 month, 3 months, and 6 months after debonding. Paired t-test, independent t-test, and non-parametric test were used for statistical analysis. Results: A significant increase (p < 0.01) in incisor irregularity was observed in both self-ligating and conventional system groups. A significant reduction (p < 0.01) in second interpremolar width was observed in both groups. Mandibular arch length decreased significantly (p = 0.001) in the conventional system group but not in the self-ligating system group. A similar pattern of stability was observed for intercanine width, first interpremolar width, intermolar width, and arch depth throughout the 6-month retention period after debonding. Comparison of incisor irregularity and arch dimension changes between self-ligating system and conventional system groups during the 6 months were non-significant. Conclusions: The stability of treatment outcomes for mild to moderate crowding malocclusions was similar between the self-ligating system and conventional system during the first 6 months of retention.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.1 s.190
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• pp.27-36
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• 2007

This paper describes the development of 6-axis ankle force/moment sensor for the intelligent feet of a humanoid robot. When the robot walks on uneven terrain, the feet should perceive the applied forces Fx, Fy, Fz and moments Mx, My, Mz from the attached 6-axis force/moment sensor on their ankles. Papers have already been published have some disadvantages in the size of the sensor, the rated output and so on. The rated output of each component sensor (6-axis ankle force/moment sensor) is very important to design the 6-axis force/moment sensor for precision measurement. Therefore, each sensor should be designed to get the similar rated output under each rated load. Also, the size of the sensor is very important for mounting to robot's feet. Therefore, the diameter should be below 100 mm and the height should be below 40mm. In this paper, first, the structure of a 6-axis ankle force/moment sensor was modeled for a humanoid robot's feet newly, Second, the equations to predict the strains on the sensing elements was derived, third, the size of the sensing elements was designed by using the equations, then, the sensor was fabricated by attaching straingages on the sensing elements, finally, the characteristic test of the developed sensor was carried out. The rated outputs from the derived equations agree well with the results from the experiments. The interference error of the sensor is less than 2.94%.

• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.75-84
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• 2011

Atopic dermatitis is a chronic inflammatory skin disease associated with cutaneous hyper-reactivity to environmental triggers. In order to develop effective therapeutic herbal extracts for atopic dermatitis, cytotoxicity, antioxidant, anti-inflammatory and anti-allergic activities were investigated for various herbal extracts. Among candidate extracts, we selected Aloe vera L. (AV), Viola mandshurica W. Becker (VM), Punica granatum L. (PG), Dendrobium nobile L. (DN) and mixture of the above extracts (MX) for further investigations. All of them did not show cytotoxic activities to macrophage RAW264.7 cells below the concentration of 100 ppm. All showed antioxidant, anti-inflammatory and anti-allergic effects, although to various extents. In antioxidant effects, AV showed the highest effect, followed by PG and VM, while DN did the lowest. In evaluation for anti-inflammatory activities in macrophage RAW264.7 cells, AV and DN inhibited almost completely the LPS-induced production of nitric oxide, while AV, DN and VM showed strong inhibitory activities on the LPS-induced production of TNF-${\alpha}$. In anti-allergy effect in mast cell HMC-1, DN showed the highest effect, followed by AV and PG, while VM did the lowest. In the topical allergy reaction induced by compound 48/80 in Sprague-Dawley rat, DN exhibited significant anti-allergic effect, while PG, VM and AV did slight effect. These results suggest that AV, VM, PG and DN have antioxidant, anti-inflammatory and anti-allergic activities, and thus have the potential to reduce and alleviate the symptoms of atopic dermatitis.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1097-1102
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• 2007

This paper describes the development of 6-axis force/moment sensor for an intelligent robot's foot. In order to walk on uneven terrain safely, the foot should perceive the applied forces Fx, Fy, Fz and moments Mx, My, Mz to itself. The applied forces and moments should be measured from a 6-axis force/moment sensor attached to a humanoid robot's foot(ankle). They in the published paper already have some disadvantage in the size of the sensor, the rated output and so on. The rated output of each component sensor (6-axis force/moment sensor) is very important to design the 6-axis force/moment sensor for precision measurement. Therefore, each sensor should be designed to be gotten similar the rated output under each rated load. So, the sensing elements of the 6-axis force/moment sensor should get lots of design variables. Also, the size of 6- axis force/moment sensor is very important for mounting to robot's foot. In this paper, a 6-axis force/moment sensor for perceiving forces and moments in a humanoid robot's foot was developed using many PPBs (parallel plate-beams). The structure of the sensor was newly modeled, and the sensing elements (plate-beams) of the sensor were designed using FEM (Finite Element Method) analysis. Then, the 6-axis force/moment sensor was fabricated by attaching strain-gages on the sensing elements, and the characteristic test of the developed sensor was carried out. The rated outputs from FEM analysis agree well with that from the characteristic test.