• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.494-503
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• 2013

In this study, $CO_2$ adsorbent was produced for minimizing energy loss due to ventilation within the building. For improved selectivity about low concentration of $CO_2$ in multiple-use facilities, the ball type adsorbent was modified from a commercial zeolite, alumina, alkali metals and activated carbon with mixing LiOH, binder, and $H_2O$. We measured specific surface area, pore characteristic, and crystal structure of the modified adsorbent. Effects of alkalization on the absorptive properties of the adsorbents were investigated. Continuous column tests (2,000 ppm) and batch chamber tests ($4m^3$, 5,000ppm) showed that the modified adsorbent indicated about the selectivity of $CO_2$ more than 9.7% (0.613 mmol/g) compared with ordinary adsorbents and $CO_2$ removal efficiency of 88.8% within l hour, respectively. It was estimated that the modified adsorbent was applicable to indoor environments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.665-671
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• 2017

The alkali-Metal Thermal-to-electric Converter (AMTEC) is one of the promising static energy conversion technologies for the direct conversion of thermal energy to electrical energy. The advantages over a conventional energy converter are its high theoretical conversion efficiency of 40% and power density of 500 W/kg. The working principle of an AMTEC battery is the electrochemical reaction of the sodium through an ion conducting electrolyte. Sodium ion pass through the hot side of the beta"-alumina solid electrolyte (BASE) primarily as a result of the pressure difference. This pressure difference across the BASE has a significant effect on the overall performance of the AMTEC system. In order to build the high pressure difference across the BASE, hermeticity is required for each joined components for high temperature range of $900^{\circ}C$. The AMTEC battery was manufactured by utilizing robust joining technology of BASE/insulator/metal flange interfaces of the system for both structural and electrical stability. The electrical potential difference between the anode and cathode sides, where the electrons emitted from sodium ionization and recombined into sodium, was characterized as the open-circuit voltage. The efforts of technological improvement were concentrated on a high-power output and conversion efficiency. This paper discusses about the joining and performance of the AMTEC systems.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1719-1721
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• 2012

We have investigated the $H_2$ adsorption structures and binding energies of the metal (M)-doped (M = Li, Na, K, Mg, and Al) silicon complexes, $M-Si_{19}H_{11}$ and $M-Si_{24}H_{12}$, using density functional calculations. Alkali metals are preferred as doping elements because the Mg-Si and Al-$H_2$ interactions are weak. The maximum numbers of $H_2$ molecules that can be adsorbed are four and five for M=Li and K, respectively. We propose that the K-decorated silicon material might be an effective hydrogen storage material with high hydrogen capacity and high reversibility.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.2
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• pp.116-121
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• 2017

To overcome the low reactivity and solubility of alkali metal fluorides (MFs), various types of phase transfer catalysts (PTCs) have been developed over the last decades. However, since the fluoride activated by such PTC sometimes has a strong basicity, it may cause various side reactions such as elimination reaction or hydroxylation reaction in the nucleophilic fluorination reaction. Also, they may cause separation problems in the compound purification process. In recent advanced study, various PTCs have been developed to solve these problem of conventional catalyst. In this review, we would like to introduce three kinds of novel multifunctional organic catalysts such as bis-tert-alcohol-functionalized crown-6-calix[4]arene (BACCA), easy separable pyrene-tagged ionic liquid (PIL) by reduced graphene oxide (rGO), and tri-tert-butanolamine organic catalyst.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.300-303
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• 2015

GaSe Single tetralayer의 $4{\times}4$ supercell을 사용하여 alkali metal (Li, Na)의 안정한 흡착 위치를 계산하였다. 가능한 흡착 위치로써 hollow, on top of Se, on top of Ga, Ga-Se bridge, Se-Se bridge를 조사하였다. 위치에 따른 흡착 에너지를 DFT 계산을 통해 얻었고, 계산 값을 통해 가장 안정한 위치를 선정하였다. 그 결과 하나의 원자가 흡착 될 때의 가장 안정한 위치는 hollow 위치이고, bridge 위치는 불안정하다는 것을 알 수 있었다. 또한 가장 안정한 hollow 위치에 두 개의 원자를 거리를 변화시키며 흡착 시켜 계산한 결과, 가장 가깝게 흡착 되었을 때 가장 안정했고 이때 tetralayer의 구조 변형이 두드러짐을 알 수 있었다.

• Macromolecular Research
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• v.12 no.4
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• pp.427-430
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• 2004

Calix[4]crown-6-2,4-bis(2-hydroxyethyl ether) (2), which has crown-6 moieties at the 1- and 3-positions and hydroxyethyl functions at the 2- and 4-positions, was prepared for the syntheses of polyester 3 and polyurethane 4 by reactions with adipoyl chloride and hexamethylene diisocyanate, respectively. The ion binding characteristics of monomer 2 and polymers 3 and 4 toward alkali and alkali earth metal ions were measured by liquid-liquid extraction from the aqueous phase into the organic phase. We observed that the polyurethane 4 has a higher binding affinity toward various metal cations when compared to polyester 3, which exhibits cesium ion selectivity.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.155-155
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• 2000

Adsorption of alkali metals on a silicon surface has attracted much attention due to its importance in metal-semiconductor interface technology, In particular, the bonding nature of alkali metal to silicon substrate has been a focus of fundamental research efforts. We examined the adsorbed layer of Cs on a Si(111)-(7$\times$) surface by reactive ion scattering (RIS) of hyperthermal Cs+ beams. RIS from a Cs-adsorbed surface gives rise to Cs, representing pickup of surface Cs by Cs projectile. The Cs intensity is proportional to surface coverage of Cs at a high substrate temperature (473 K), while it varies anomalously with Cs coverage at low temperatures (130-170 K). This observation indicates that RIS selectively detects metallic Cs on surface, but discriminates ionic Cs. Transition from ionic to metallic Cs adlayer is driven by thermal diffusion of Cs and their clustering process.

• Analytical Science and Technology
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• v.11 no.4
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• pp.248-253
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• 1998

The adsorption and separation behaviors of alkali, alkaline earth and transition metal ions using a poly-dibenzo-18-crown-6 were investigated in aqueous solution. The adsorption degree(E) and distribution ratio(D) of alkali, alkaline earth metal ions were Li(I)$t_R$) of metal ions were affected by the adsorption degree(E) and distribution ratio(D). This results showed good separation efficiency of K(I), Sr(II), Ag(I) and Pb(II) from the mixed metal solution.

• Proceedings of the Korean Vacuum Society Conference
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• 1996.06a
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• pp.127-127
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• 1996

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2806-2808
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• 2009