• Applied Science and Convergence Technology
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• 제25권5호
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• pp.92-97
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• 2016

Surface erosion using focused ion beam irradiation is the most promising technology for the realization of micro/nanofabrication. However, accurate fabrication of predefined structures is still challenging. This article introduces a single step surface driving method to fabricated predefined curved structures. The previously reported multi step surface driving method (MSDM) has been modified so that a single ion dose profile can be used instead of multiple ion dose profiles. Experimental realization of the method is presented with the fabrication of predefined curved surfaces as well as reference to surface propagation theory. For the purpose of verification, simulations are performed on the basis of a sound mathematical model.

• 한국의학물리학회지:의학물리
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• 제31권3호
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• pp.71-80
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• 2020

This paper provides a brief review of the advanced technologies for carbon ion radiotherapy (CIRT), with a focus on current developments. Compared to photon beam therapy, treatment using heavy ions, especially a carbon beam, has potential advantages due to its physical and biological properties. Carbon ion beams with high linear energy transfer demonstrate high relative biological effectiveness in cell killing, particularly at the Bragg peak. With these unique properties, CIRT allows for accurate targeting and dose escalation for tumors with better sparing of adjacent normal tissues. Recently, the available CIRT technologies included fast pencil beam scanning, superconducting rotating gantry, respiratory motion management, and accurate beam modeling for the treatment planning system. These techniques provide precise treatment, operational efficiency, and patient comfort. Currently, there are 12 CIRT facilities worldwide; with technological improvements, they continue to grow in number. Ongoing technological developments include the use of multiple ion beams, effective beam delivery, accurate biological modeling, and downsizing the facility.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.152-158
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• 2021

Electrospray ionization (ESI) and ion mobility spectrometry-mass spectrometry (IMS-MS) were employed to investigate the solvated structures of ionic species in the lithium iodide electrolyte solution in the gas phase. The Li⁺I^-Li⁺ triple ion and single standalone Li+ ions solvated by 1,4-dioxane were successfully generated and observed by ESI-MS under the influence of dioxane vapor at the inlet region. Under the present experimental condition, (1,4-dioxane)_m·Li⁺ complex ions (m = 1, 2, and 3) and a (1,4-dioxane)·Li⁺I^-Li⁺ complex ion were observed, which were further examined by IMS to investigate their structures. The presence of multiple structural isomers was confirmed, which accounts for the endothermic conformational transition of 1,4-dioxane from a chair to a boat to achieve bidentate O-donor binding to Li⁺ and Li⁺I^-Li⁺. Further structural details critical for the ion-solvent interactions were also examined and discussed with the help of density functional theory calculations.

• Bulletin of the Korean Chemical Society
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• 제19권11호
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• pp.1249-1252
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• 1998

• 전기학회논문지
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• 제60권1호
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• pp.142-149
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• 2011

This paper presents a new state of charge(SOC) estimation of large capacity of Li-ion battery (LIB) based on the multiple model adaptive estimation(MMAE) method. We first introduce an equivalent circuit model of LIB. The relationship between the terminal voltage and the open circuit voltage(OCV) is nonlinear and may vary depending on the changes of temperature and C-rate. In this paper, such behaviors are described as a set of multiple linear time invariant impedance models. Each model is identified at a temperature and a C-rate. These model set must be obtained a priori for a given LIB. It is shown that most of impedances can be modeled by first-order and second-order transfer functions. For the real time estimation, we transform the continuous time models into difference equations. Subsequently, we construct the model banks in the manner that each bank consists of four adjacent models. When an operating point of cell temperature and current is given, the corresponding model bank is directly determined so that it is included in the interval generated by four operating points of the model bank. The MMAE of SOC at an arbitrary operating point (T $^{\circ}C$, $I_{bat}$[A]) is performed by calculating a linear combination of voltage drops, which are obtained by four models of the selected model bank. The demonstration of the proposed method is shown through simulations using DUALFOIL.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.557-560
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• 1998

We previously developed and presented the 3D ion implantation simulation code, TRICSI. In this paper, we performed the multiple implants into (100) silicon substrate with our recently enhanced version. Our results for the multiple implants were compared with the previously published SIMS data and obtained the good agreements. In this paper the channeling behaviour of implanted impurity and the damage accumulation are analyzed and discussed in the simple 3D structure, named the Hole structure which has a rectangular implant window.

• 전자공학회논문지
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• 제54권2호
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• pp.141-145
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• 2017

본 논문에서는 휴대용 전자기기에 널리 사용되고 있는 리튬-이온 충전용 전원 모듈에서 발열을 줄이면서 배터리의 충전 시간을 단축하기 위한 기법을 연구하였다. 제안하는 기법은 마스터 충전 모듈과 슬레이브 충전 모듈로 구성된 다중 충전 모듈을 이용하여 병렬적인 전류 경로를 구성하면서 단일 선로 통신 방식을 적용함으로써 추가적인 하드웨어를 최소화하여 충전 회로를 매우 간단하게 구성할 수 있도록 하였다. 마스터 충전 모듈과 슬레이브 충전 모듈 간의 단일 선로 통신 방식은 필요 부품의 핀 개수를 최소화하고 디지털 통신 방식을 사용하지 않고 전압 레벨을 이용한 통신 방식을 적용하였기 때문에 구현 면적이 줄어들고 비용적인 측면에서도 유리한 장점이 있다. 따라서 본 논문에서 제안한 충전 기법은 고속의 충전을 필요로 하는 충전식 전원 모듈의 구현에 실용적으로 적용 가능할 것으로 기대한다.

• Nuclear Engineering and Technology
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• 제56권4호
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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.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.92-99
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• 2010

Photoexcitation of a precursor ion inside a cell floated at high voltage installed in a tandem time-of-flight (TOF) mass spectrometer provides triple tandem mass spectrometric information and allows kinetic and mechanistic studies. In this work, the factors affecting, or downgrading, the performance of the technique were identified. Ion-optical and computational analyses showed that an optimum instrument could be designed by utilizing a reflectron with linear-plus-quadratic potential inside. Theoretical predictions were confirmed by tests with instruments built with different ion-optical layout. With optimized instruments, masses of intermediate ions in the consecutive dissociation of a precursor ion could be determined with the maximum error of $\pm5$ Da. We also observed excellent agreement in dynamical parameters (critical energy and entropy) for the dissociation of a model peptide ion determined by instruments with different ion-optical layout operated under optimum conditions. This suggests that these parameters can be determined reliably by the kinetic method developed previously when properly designed and operated tandem TOF instruments are used.

• 한국의학물리학회지:의학물리
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• 제29권2호
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• pp.53-58
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• 2018

This paper evaluates patient-specific quality assurance (PSQA) in the treatment of small and multiple tumors by the CyberKnife system with fixed collimators, using an ion chamber and EBT3 films. We selected 49 patients with single or multiple brain tumors, and the treatment plans include one to four targets with total volumes ranging from 0.12 cc to 3.74 cc. All PSQA deliveries were performed with a stereotactic dose verification phantom. The A16 microchamber (Standard Imaging, WI, USA) and Gafchromic EBT3 film (Ashland ISP Advanced Materials, NJ, USA) were inserted into the phantom to measure the point dose of the target and the dose distribution, respectively. The film was scanned 1 hr after irradiation by a film digitizer scanner and analyzed using RIT software (Radiological Imaging Technology, CO, USA). The acceptance criteria was <5% for the point dose measurement and >90% gamma passing rate using 3%/3 mm and relative dose difference, respectively. The point dose errors between the calculated and measured dose by the ion chamber were in the range of -17.5% to 8.03%. The mean point dose differences for 5 mm, 7.5 mm, and 10 mm fixed cone size was -11.1%, -4.1%, and -1.5%, respectively. The mean gamma passing rates for all cases was 96.1%. Although the maximum dose distribution of multiple targets was not shown in the film, gamma distribution showed that dose verification for multiple tumors can be performed. The use of the microchamber and EBT3 film made it possible to verify the dosimetric and mechanical accuracy of small and multiple targets. In particular, the correction factors should be applied to small fixed collimators less than 10 mm.